Equine Health // Category

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08 May

How would you know if you have a healthy horse?

Did you know that you are the very best person to determine if your horse is “under-the-weather”? You know what is “normal” behaviour for your own horse and what are their habits. Just by observing your horse’s day to day routine, you can get a feel for its general well-being and identify any potential health issues. If you do become concerned about something, you will be better equipped to give the veterinarian a detailed account of when the horse was last normal and what now appears to be wrong, to help in their assessment.
So what things should you do every day to monitor the health status of your horse?

Here is a list of health checks that you should include:

TPR – Temperature, Pulse (Heart Rate) and Respiration Rate. It is important to know your horse’s TPR or vital signs. It is preferable to take these at the same time of day, when the horse is at rest and not stressed.

Temperature: The normal body temperature of a horse should be between 37.0 and 38.5 degrees Celsius (98.6 and 101.3 Fahrenheit). Body temperature can be elevated because of inflammation and infection, but don’t forget, that a horse’s temperature can also increase when exercising, when rugged, in hot weather and when they are excited. Body temperature fluctuates during the day, and is often slightly higher later in the day. In mares, temperature can be seen to fluctuates with their heat cycle.

Body temperature should be taken rectally, ideally with a digital thermometer. (You can purchase a digital thermometer from your local pharmacy).  If you have never taken a horse’s temperature before, get your veterinarian/instructor etc. to show you how.

Equine rectal temperature taken with digital therometer
Take temperature rectally with digital thermometer

Respiration Rate: (breathing) Watch your horse breathing over a full minute. When it inhales and then exhales, it has taken one breath. The normal breathing rate for an adult horse at rest is 8 to 12 breaths per minute. In contrast, a new born foal will breathe 60-80 times a minute, and an older foal will take 20-40 breaths.

There are some different techniques to determine the respiratory rate. Firstly, you can stand near your horse’s shoulder, facing towards its hindquarters and watch its abdomen move in and out (one breath). Another method is feeling air coming out of the nostril on your hand. Or, you can listen to the breath sounds as air passes through the trachea (windpipe) using a stethoscope. Using a stethoscope to listen to the trachea will enable you to hear the sounds your horse makes when breathing. You might notice deep or shallow breaths,, and you might hear unusual crackling or whistling sounds that are an indication that you should consult veterinarian.

As with a horse’s temperature, the respiratory rate will also increases with exercise, excitement, and in hot weather.

Take respiration rate by placing hand in front of nostrils to feel air exhaled
Take respiration rate by placing hand in front of nostrils to feel air exhaled
Watch the flanks in and out to determine respiration rate
Watch the flanks to determine respiration rate. In and out is one breath

Heart Rate: (Pulse) The resting heart rate of a healthy horse should be between 32-40 beats per minute (bpm). Draft horses will have a slightly lower normal rate, and foals will have a much higher one, up to 60-100bpm. Newborns will be towards the upper end of the scale, while older foals will have lower heart rates under normal conditions.

To take the heart rate, place a stethoscope on the chest just behind the elbow on the left side of the horse. Count the beats for a full minute, if you can, or for 30 seconds and then multiply by two to get the heart rate per minute. If you don’t have a stethoscope, don’t worry. You can take the pulse by putting your finger on the mandibular artery, found running across the underside of the jaw, just where it joins the cheek or in the groove under the jaw inside the cheek, the radial artery on the inside of the knee, or the digital arteries at the back and bottom of the fetlock and along both sides of the pastern, at 4 and 8 0’clock. Be sure to use your fingers as you might feel the pulse in your own thumb.
Pain, inflammation and stress are can cause the heart rate to increase, as too can exercise, heat and excitement.

Use a stethoscope to determine heart rate
Take the heart rate with stethoscope placed immediately behind the near-side elbow.

Those were the vital signs explained, but there are several other things you can keep an eye on every day to know how your horse is doing.
Eyes: Your horse’s eyes should be open, clear and bright with no discharge or swelling. If you notice excessive discharge or weeping, swelling around the eye or in the corner of the eye, closed or partially closed eyelid, sensitivity to light, or cloudiness, contact your veterinarian immediately. Eye problems must always be tended to urgently:

A clear bright eye.
The eye should be clear, bright, open and no signs of discharge or swelling

Demeanour: Has your horse changed the way it acts? Horses should be alert and inquisitive, watching any changes in their environment. If your horse looks a bit sad, is uninterested in what is happening around them, and its head is down (and it is not eating or sleeping), your horse is off-colour and some further investigation is required. Contact your veterinarian.

Eating: Do you keep an eye on your horse’s feed bin or watch how much time is spent grazing in the paddock? Did you know that when turned out on pasture, a horse will graze about 18 hours a day? Keep an eye on your horse to see if it is spending more time grazing or standing around? If your horse is standing around more than grazing or leaving feed in its bin and this is not “normal” behaviour, then this should be investigated. Take your horse’s temperature and call your veterinarian immediately. The veterinarian will do a more complete exam and may check the teeth or ask when your horse last had dentistry.

Keep a watch on your horse's feed bin to make sure they are eating up
Keep an eye on your horse’s feed bin – is it licked clean or is your horse leaving feed?

Mucous Membranes: The mucous membrane are the tissues that line the gums, inside of the mouth, inside of the eyelid, inside of the nostrils and the sac in the corner of the eye. They should be pink, in colour and moist to touch. If the gums are dry or tacky to touch this can be an indication that the horse is dehydrated. Check the colour of your horse’s gums. If they are white, dark red, blue, or yellow tinged call your veterinarian immediately, as these changes in colour indicate serious health issues.

Healthy, pink and moist gums (mucous membrane).
Healthy, pink and moist gums (mucous membrane).

Capillary Refill Time: This gives a good indication of how well the horse’s circulatory system is working. (A normal capillary refill time indicates that blood and oxygen is moving efficiently around the body). Push your finger on the gum for a few seconds until the gum in that area goes white, then release. The area should return to its original pink colour, within two seconds, as the blood returns to the area. If it takes longer than two seconds to return to normal or the gum are any colour but pink, call your veterinarian

Capillary Refill Test
Check capillary refill time – press on gum for a few seconds the area will go white, when released the gum should return to normal colour within 2 seconds

Skin Pinch Test (Skin Tent Test): This is another test to check your horse’s hydration status. On the neck, or on the upper eyelid if you are able, pinch a piece of skin between your thumb and forefinger, for a second. When you release the skin, it should return to normal within one second. If it stays pinched for more than a second, there is the possibility of dehydration. The skin tent performed on the neck can be affected by age a body condition with older animals and thin animals having a slower skin tent than younger and thinner animals. In horses, unlike in humans, the loose skin above the eye isn’t as affected by age, and fat doesn’t really accumulate under the eyelid.

Skin Pinch Test to check hydration status
Skin Pinch Test to check hydration status.

Gut Sounds: You will generally need a stethoscope to listen to your horse’s gut sounds, though by simply pressing your ear to your horse’s flank in the right place, you will likely hear some. Place your stethoscope on the belly, just behind the ribs and in front of the stifle, on both sides. The second place to listen is a little further straight up from there, about the width of your hand in front of the whorl and about a hand’s width below it. Depending on the size of your horse, the specific location varies, so ask your veterinarian to help. You should be able to hear fluid rushing, tinkling, squeaking, gurlgling or rumbling in all four areas, but you will likely hear less in the top left area than in the others. You must be patient to hear gut sounds as they are not continuous. Listen for a full minute in all four places. Ideally, we expect to hear the sounds of gut contents moving a couple of times a minute. If gut sounds are very infrequent or not present at all, this can be cause for concern as there may be a blockage. Call your veterinarian immediately.

Listen for gut sounds
Listening for gut sounds a full minute in each of the four quadrants

Check your horses stall/paddock/stable for manure as this is a good indication of how long it has been since the gut was working normally. Researchers have found that eating or drinking results in more food particles and fluid passing through the digestive tract and an increase in gut sounds. If the rumbling continues at a much higher rate than normal, it may indicate some underlying issue and a veterinarian should be consulted. In general, a slightly more active gut is not serious while a quiet gut will always require urgent veterinary care.
Water Consumption: Your horse needs access to clean, fresh water 24/7. A resting horse on a mild day can consume between 20 to 40 litres of water (five litres of water/100 kg of body weight). This amount can increase dramatically (up to 100 litres) after exercise, on hot days, or if lactating (broodmare feeding her foal milk). Horses also don’t like to drink water that is too cold, so if you live in cooler climates, make sure ice and snow is removed from water troughs and buckets. Some horses won’t drink as much if they graze on green, lush pastures as these will have a high-water content.

If you have difficulty getting your horse to drink, make sure the water is not too cold, is clean, and is fresh. If they are still not drinking that well, you can try offering an additional bucket of water with molasses or other tasty flavourings added to it to encourage drinking. Sometimes horses don’t like the smell or taste of plain water they are not used to. When you travel with your horse, if they are fussy about water, try bringing some from home, or if your horse enjoys a drink of molasses flavoured water at home, you can just bring some molasses with you to add to camouflage the taste and smell.)

Horse drinking clean, fresh water
Horses require clean, fresh water 24/7.

Urine: – What colour is your horse’s urine? It should be a pale green/yellow colour a little like apple juice. If it is darker and thicker in consistency it may be an indication of dehydration, kidney issues, or tying up. Due to the calcium content of equine urine, cloudy or foamy urine is also normal. Have you watched your horse urinating? Your horse should pass about 8-10 litres of urine per day, and should urinate about every five hours. If your horse is having difficulty stretching out to urinate, this could be an indication of lameness, muscle soreness or kidney issues.

Horse urinating
Horse is well stretched out to urinate, urine is pale green/yellow colour.

Manure: Have you checked your horse’s manure? If not, it might be time to take a closer look. Horse manure should be a rich medium brown colour and should be a formation of small round balls that shatter when they hit the ground. Your horse should pass manure six to eight times per day. In the spring, when pasture is more lush, the manure can get a green tinge and be quite soft. It can also be a bit loose at times of stress, after excessive electrolyte administration, or if there has been a change in diet. If soft manure continues for more than a few days, you should consult your veterinarian. Manure that is actually runny or is soaking the underside of the tail may indicate an urgent problem, so your veterinarian should be called immediately. If your horse’s manure are dry round balls that stay formed when they hit the ground this can be an indication that the horse is suffering from dehydration.

Horse Manure small balls shattered on hitting the ground
Small balls of manure that have shattered on hitting the ground = good!

Hoof Wall Temperature: An easy health check for your horse is to feel each hoof to see how hot it is. Hoof walls should generally be cool to touch, however each horse will be different. Get to know how warm your own horse’s hooves are in a variety of conditions. Exercise and warm weather can cause them to have an increase in temperature, so mildly warmer feet are not always a problem. It is especially useful to compare the temperature of the feet to each other. If one foot is warmer than the other, that is reasonably reliable indication of inflammation in the warm foot. It may indicate a bruise, the start of a hoof abscess, coffin joint synovitis, or a fracture.

Tip: watch to see if all four feet dry at a similar speed. Warmer feet will dry faster. If both feet are unusually hot for the conditions, it may be an indication of laminitis. A sudden flare up of laminitis is always an emergency, so call your veterinarian immediately.

Feeling hoof wall for any heat
Feel all four feet to determine if any heat present.

Digital Pulse: Another indication of inflammation in the foot is a digital pulse. The digital pulse can be found on the back of the fetlock at the base of the sesamoids. By gently pressing and sliding your fingers side to side at the back and base of the fetlock, you can often feel the firm digital artery which supplies blood to the extremities roll under your finger. Once you locate it, lighten the pressure slightly to feel the pulse through it. You can also feel the digital arteries as they continue along the pastern at 5 and 7 o’clock, and only light pressure is required to feel the pulse here. If the pulsing or throbbing is quite strong and you can feel it easily, this may actually be an abnormal digital pulse and your veterinarian may need to do some further investigation. The normal digital pulse is a tricky one to locate, and this can be even more difficult on fit, healthy horses. If you get the opportunity, ask your veterinarian or instructor to show you how to locate it and try to get familiar with how mild that pulse is when it is normal.

Feeling for a digital pulse
Locating the digital pulse can be tricky especially on fit horses ask your veterinarian to show you where to locate if you are having trouble.

It is a good practice, as a horse owner, to know what is “normal” for your horse. As every horse is different, if you know the basic health information about your horse, you can quickly recognise when it is unwell.

  1. Keep a record of daily health parameters in your first aid kit or stable so you have easy access to it. Remember, the more information you can give the veterinarian, the easier it will be for them to assess your ailing equine friend.
  2. Knowing your horse’s vital signs (TPR – Temperature, Pulse and Respiration) is a good start towards having a clearer picture of your horse’s health status.
  3. Finally, running your eyes and hands over your horse each day could show up any swellings, skin conditions, cuts, or abrasions which may need attention.
08 May

Below is a story from Michele of New Lives Animal Rescue based in the Waikato, NZ. This organisation was established in 2014 and is a Registered Charity that specialises in the rescuing and re-homing of dogs, puppies, cats kittens, horses and can accommodate other species where possible.
Pro-Dosa INTERNATIONAL are proud to be able to provide support to New Lives Animal Rescue and to then see how well these rehabilitation cases are progressing with the help of Pro-Dosa BOOST is really very cool!

“Thank you so much Pro-Dosa for your wonderful ongoing support of New Lives Rescue horses. We just love your BOOST paste!
All our rescue horses are given your paste on arrival, we find it is a great pick me up tonic and shows an immediate difference

08 May

We thought it might be an appropriate time to tell you about how incorporating Pro-Dosa BOOST into your final stages of preparation could benefit your horse when training, travelling and racing.  Pro-Dosa BOOST contains vitamins, minerals and amino acids in balanced proportions to replace those essential nutrients loss during exercise and when under stress.

Horses under stress (through hard work, travel and racing etc.) have increased requirements for a broad complex of nutrients necessary to support metabolism, health, performance, and recovery.  Unfortunately, when horses are under stress, they tend to go off their feed, resulting in reduced intake of essential nutrients just at the time they need more.

Horses have significantly increased requirements for B-vitamins at these times, and Pro-Dosa BOOST contains all of them in doses that are properly balanced with each other and with all of the other nutrients required for their absorption and function.  B group vitamins play an important role in coat and skin condition, energy production (so tired or lethargic horses may get a lift), nerve cell function (so nervous horses may be better able to relax and focus), and red blood cell production.   Most importantly, when horses are transported and then tabled in a new environment, they help to maintain normal appetite!

Pro-Dosa BOOST contains a sizable dose of Vitamin C which supports immune function and helps to protect muscle cells from oxidative damage that occurs in transport and training. (Did you know that oxidative muscle cell damage can occur in as little as one hour, as the horse works to keep itself balanced during transportation)?   Horses will arrive at their destination in the best possible condition if given one full tube of Pro-Dosa BOOST a couple of hours prior to loading them on the float each day.  If you are leaving early in the morning, it can be given the night before instead.

If you have a nervous horse that does not settle into its new environment, try giving it half to one full tube of Pro-Dosa BOOST each day.  It contains as much Magnesium and Thiamine as many calming products, and these nutrients actually work better when given in combination with each other and with the amino acids, Tryptophan and Tyrosine, than when administered separately.

Pro-Dosa BOOST contains a broad range of electrolytes including calcium, magnesium, and phosphorus, as well as sodium, potassium, and chloride.  These will help maintain normal hydration and the electrolyte balance necessary for muscle cell, cardiac, and nerve function.    Once horses are dehydrated, however, electrolytes will fail to stimulate thirst.  When that occurs, unassembled amino acids stimulate thirst more effectively.

Pro-Dosa BOOST contains 22 unassembled, rapidly-absorbable amino acids in the optimal ratios required for protein synthesis and muscle development.  Muscle cells take up amino acids most efficiently for about an hour following hard work.  Providing a full tube of Pro-Dosa BOOST as quickly as possible after the last hit out prior to racing will aid muscle cell repair and recovery, ensuring horses will be in top condition on race day.  A full or a half tube fed regularly after each fast work can help your horse to recover well, maintain normal body condition, and perform consistently over the long racing season ahead.

 

When race day comes around, give one full tube of Pro-Dosa BOOST on the tongue the night before or mix it in with feed.

We wish you the very best of luck over this fantastic racing carnival. if you require any further information.  Contact the team at Pro-Dosa International.

08 May

Equine Gastric Ulcer Syndrome (EGUS) is a term that covers the damage and ulceration of the stomach lining in the horse. EGUS is a very prevalent disease affecting horses. EGUS is found in up to 90% of all race horses and endurance horses. The incidence of EGUS in sporthorses can also be as high as 60%.

The Stomach and Digestion Process.

The stomach is small relative to the size of the digestive tract of the horse and has a small role in the digestion process to help further liquefy food particles as they pass through to the small intestine.

The stomach has two distinct areas the non-glandular section which is located the top one third of the stomach and has the same thin, smooth wall lining as the oesophagus.  The glandular section of the stomach is the remaining two thirds of the stomach its wall lining is made up of glands which secrete hydrochloric acid, pepsin, bicarbonate and mucous.

The Equine Stomach showing the Glandular & Nonglandular Sections
Richards, Elenor – Equine Stomach, Nutrition for Maximum Performance


The horse is unique in that it continuously secretes hydrochloric acid to break down food particles.  It also produces the enzyme pepsin that helps break down proteins.  It is these gastric acids that ultimately damage the non-glandular region of the stomach as this area has thin, smooth walls which are not protected by glands as found in the glandular region of the stomach.
The time it takes for feeds to be digested in the stomach varies with the type of feed, forage or grain and the size of the meal.  Grain can take as little as ten minutes to pass through the stomach and forage can take up to 24 hours so the stomach has little time to empty and hydrochloric acid is being used to break down food particles.

To address EGUS, our aim is to neutralise the stomach acid and the horse has its own neutralising agent bicarbonate which is produced in its saliva.  As a horse chews it produces saliva the more time it chews the greater the amount of saliva thus bicarbonate produced. The bicarbonate then reacts with to neutralize the gastric acids.

It is important that all stable staff know the horses that are in their care so they are able to determine when there has been a change in their behaviour, eating habits, weight loss etc which could well mean the early detection of EGUS.

Clinical Signs of EGUS

The following are clinical signs that different studies have found can indicate EGUS.

  • Horse cast or lying on its back
  • Grinding its Teeth
  • Poor Performance
  • Weight Loss and Poor Body Condition
  • Dull or poor coat
  • Colic (Abdominal Pain)
  • Changes in attitude and behaviour
  • Poor Appetite

The only way to absolutely diagnose EGUS is by gastroscopy which is a long endoscope with a light and camera that is passed into the stomach via nostril and eosphogus to identify any ulcerations or damage to the stomach lining.

Management & Nutrition

  • Provide high quality forage ad-lib, 1 kg of forage requires the horse to chew approximately 3000 times producing high quantities of saliva and bicarbonate to help neutralise gastric acid.  Alfalfa high in protein 21% and calcium is ideal as there are buffering qualities provided by the calcium.
  •  Provide Water ad-lib at all times – water is required to produce saliva and studies show horses who are intermittently without water are more susceptible to ulcers.
  •  Keep horses on pasture 24/7 if at all feasible, as they are grazers and can do so for up to 18 hours per day and this will help keep feed passing through the stomach working to neutralize gastric acids.
  • If horses are stall confined, make sure they can see other horses and can socialise to reduce stress.  Give them a ball or something else to keep them amused and free from boredom.
  • Feed smaller feeds more often, due to labour and time constraints many stables make the mistake of only feeding horses twice a day, which means the horse can go without feed for a period greater than six hours which studies suggest increases the likelihood of EGUS.  Horses were designed to graze throughout the day not eat once or twice.
  • Start with forage and build the diet from there adding a vitamin and mineral balancer then adding energy sources to meet requirements of the horse.  Remember you can add fats such as oils to replace grain.
  • If the horse bolts its feed place rocks in its feeder to try and slow its feeding rate down making it chew the feed, which means it takes more time for the feed to pass through the stomach.
  • Transportation is a cause of EGUS – to help eliminate this break up longer travel periods to allow for rest, feed and water.  Provide a travel companion to help alleviate stress.
  • Performance horses are more susceptible to EGUS as they are often fasted prior to racing or competing, this needs to be addressed by the stable so the stomach does not completely empty out.
  • Grains and or concentrates should never make up more than 1 – 2 kg of any meal given to the horse.  Especially if it contains Sweetfeeds as these contain VFAs (volatile fatty acids) which can cause damage to the non-glandular stomach lining.
  1. Turning the horse out on pasture with access to quality forage for a period of a month will most likely allow the healing of any stomach ulcers, however this may not be practical for performance horses.
  2. The only registered treatment for the treatment of ulcers is Omeprozole (Gatroguard or Ulcerguard).
  3. There are other solutions available that line the stomach to help reduce the pain associated from ulcers.

If you require a PDF version of this fact sheet please click here and we will send one to you.

For more information read Dr Jenny Stewart “Update on Ulcers

References

  1. Cubitt, Tanya. PhD,The Horse’s Digestive System,Hygain Health & Nutrition Articles
  2. Sykes, B.W., Hewetson, M., Hepburn, R.J., Luthersson, N. and Tamzali, Y. (2015), European College of Equine Internal Medicine Consensus Statement—Equine Gastric Ulcer Syndrome in Adult Horses. Journal of Veterinary Internal Medicine, 29: 1288–1299. doi: 10.1111/jvim.13578
  3. Andrews, Frank. M. DVM, MS, DACVIM,American Association of Equine Practitioners,Equine Gastric Ulcer Syndrome (16 June 20216),Website – Horse Health Publication 816
  4. Lesté-Lasserre, Christa. MA,TheHorse.com,Got Ulcers? (1 February 2014),Website – Article 33283
  5. Merck Veterinary Manual,Gastric Ulcers in Horses: Gastrointestinal Ulcers in Large Animals
  6. McClure, Scott. R, DVM, PhD, Diplomate ACVS, Diplomate ACVSMR, American Association of Equine Practitioners,Equine Gastric Ulcers: Special Care and Nutrition,Website – Horse Health Publication 817 (January, 2016)
  7. Geor, Ray. J. DVM, PhD.,American Association of Equine Practitioners,How Horses Digest Feed,Website – Horse Health Publication 861 (February, 2016)
  8. Liburt, Nettie. PhD, MS,TheHorse.com,Tips for Managing Gastric Ulcers in Performance Horses,Website – Articles 37542 (9 May 2016)
  9. Drs. Foster & Smith,Gastric Ulcers in Horses: Causes, Signs, and Treatments,Website – Article 1587
  10. Niteo, Jorge. DVM, PhD, DACVS,Centre for Equine Health, School of Veterinary Medicine, University of California, Davis,Diagnosing and Treating Gastric Ulcers in Horses,CEH Horse Report (October 2012)
  11. Kentucky Equine Research,Gastric Ulcers in Horses – A widespread but Manageable Disease,Vetzone,Article (June 2012)
08 May

Upper respiratory infections are a significant problem across all equine industries and in the racing industry, in particular.  Studies have demonstrated considerable economic losses resulting from subclinical disease (when horses don’t look obviously sick but are performing below expectations), from acute infection (when horses have nasal discharge, a cough, and obviously need rest or a reduction in training), and from the hypersensitivity and chronic inflammatory airway disease that develops in the lungs as a result.1, 2   As there has been a sudden increase in the number of upper respiratory infections in racing stables in New Zealand over recent months, I thought now might be a good time to write something about Equine Herpes Virus.

Most frequently, outbreaks coincide with yearling sales or a change in season, as this is the time of year in which racing stables introduce new horses to their yards, many of whom will bring “colds” or upper respiratory infections with them.  Horses get “colds” just like people.  They will have a fever, runny nose, sore throat, and occasionally a cough.  Many will also appear depressed and lose their appetite.

There are a number of pathogens that cause upper respiratory infections in horses including Equine Herpes Virus, adenoviruses, rhinovirus, Equine Viral Arteritis (EVA), Streptococcus Equi Equi (Strangles), Streptococcus Equi Zooepidemicus, and Equine Influenza (EI).  (In New Zealand, so far, we haven’t had EI…touch wood…)  Equine Herpes Virus (EHV), identified over 60 years ago, remains the most common and economically significant cause of upper respiratory infections, world wide. 3,4, 5, 6, 7

There are actually nine different strains of Equine Herpes Virus, but only a few of them are clinically significant.  The most important are EHV type 1 and EHV type 4 as they produce the most virulent, easily communicable, and most costly outbreaks across equine industries, all over the world.   While EHV types 2 and 5 are ubiquitous (everywhere) and commonly cultured, the respiratory signs produced are generally mild, and they have not been demonstrated to produce serious outbreaks and economic loss.  A recent study done in New Zealand determined that 44% of individuals from a small group with nasal discharge had positive cultures for EHV type 2 and type 5 was identified in 50%.  EHV types 1 and 4 were only identified in 6% and 27%, respectively, though the small sample size and specific population tested were cited as limiting factors.  Some heathy horses also cultured positive for EHV type 2 in the study, and the author explained that there were difficulties in positively identifying EHV type 4.8  All in all, the researcher found that EHV was strongly associated with respiratory disease.  Previous studies done in New Zealand demonstrated evidence of recent EHV Types 1 or 4 infections in 72- 100% of horses and foals.9, 10

Equine Herpes Virus can be transmitted directly from horse to horse, but it can also be transmitted by droplets in the air (which can travel the length of a football field when a horse coughs). Exposure to virus particles in the environment on fences, gear, water troughs, clothing, shoes, etc. can also produce infection.

Horses of all ages are susceptible, but animals under three years of age and those under stress are most frequently affected.  This would include most weanlings, yearlings, racehorses, and horses in training of any sort. 6

Immunity from natural infection lasts for only 2 to 6 months, so the same individual can become infected more than once in a year or their lifetime.  While horses older than 5 years of age seldom show signs of illness, they often harbour the virus and provide a source of infection for the younger, more susceptible horses in the population.  Young horses, with little immunity, will almost certainly become clinically ill when exposed.   As they recover, over about 4-28 days, the virus, rather than being eradicated, enters the latent (silent) stage, sheltering in lymph nodes.6  Once the horse is under stress due to travel, training, or co-mingling at sales, the virus becomes reactivated and is shed into the environment, infecting other susceptible individuals.  Studies have shown that between 60 and 88 percent of horses may be silent carriers.6

Other Clinical Syndromes Including Abortion and Neurological Disease

Equine Herpes Virus can cause a few different types of disease syndromes including respiratory disease, abortions, and neurological problems. EHV type 4 is believed to cause the vast majority (up to 90%) of significant upper respiratory infections11  and has been identified in some abortion cases, while EHV type 1 causes the majority of abortion cases, some respiratory infections, and most of the neurological cases.6
The evidence, so far, suggests that EHV infection begins in the respiratory tract, and once the virus multiplies enough in susceptible horses, it gets into their blood stream where it produces a “viremia”.  (This just means virus in the blood.) If there is a large enough amount of virus in the blood, it gets into the central nervous system where it can damage the brain and spinal cord.  It appears that EHV-1 is the only type, or at least, the type most likely to produce neurological symptoms as it appears to be the only one that settles in central nervous tissue.12
The neurological form of EHV (Equine Herpes Myeloencephalopahy or EHM) is fairly rare, especially in Australia and New Zealand, though there is some evidence that the incidence is increasing. 13
Clinical signs often develop 8 to 12 days after a respiratory infection and begin with weakness in the hind legs and incoordination.  It can quickly progress, and within a day or two, horses will go down and be unable to get up.  In some cases, no signs of respiratory infection are obvious, and the only early indication of a problem is a fever.   Sudden weakness and death may be the first noticeable sign.

Alternatively, the viremia can allow the virus to get into the uterus.  Once there, it causes the placenta to detach and the foal to be aborted.  EHV-1 abortion was, up until the mid-80’s the most costly equine disease in North America, resulting in abortion storms that affected large percentages of mares on stud farms.  From the mid-80’s, a widespread, aggressive vaccination program was instituted, and the incidence of EHV-1 abortion was reduced by 75%.  Fortunately, in New Zealand, the incidence of abortion has been lower than in other countries.

Vaccinations

Treatment of viral infections is difficult.  There are no really effective, economical anti-viral drugs available.  Antibiotics do not kill viruses, and can only be used to treat animals with bacterial infections.

The best way to deal with EHV infection is to prevent it.  Prevention requires a multi-faceted approach including quarantine, hygiene, and vaccination programs. Isolation of sick horses and quarantine of exposed animals and premises are useful measures, but they are not always practical at racing stables and farms. When horses attend sales or races, they are almost certain to be exposed to individuals who may not have been adequately isolated at their home stables and who may be shedding virus.  Vaccination is the most practical way to reduce the rate and severity of infections in a racing stable environment where the horse population travels and changes regularly and in the racing industry as a whole.

Vaccinating a single horse will not reliably prevent that horse from getting sick if it is exposed to an overwhelming dose of virus.14  Instead, to protect individual horses from viral infection, it is necessary to produce “herd immunity”.  The epidemiological term, herd immunity, can be explained like this.  If 100 percent of the horses on a farm are vaccinated, it is expected that 70 percent of those horses will become immune.  If 70 percent of the individuals in a population have immunity, then virus will not have enough susceptible hosts in which to multiply. This will reduce the overall viral load in the environment and reduce the viral challenge to each individual.  This will stop the transmission of virus in the herd.14

That is the long way of saying that ALL of the horses on a farm or in a population must be vaccinated to prevent respiratory infection from being transmitted from horse to horse and therefore to protect individual horses.

A vaccinated horse may still get sick if it is exposed to an overwhelming viral challenge at the races or during shipping.  They may be exposed to a sick horse or placed in a stall where a sick horse has been. Vaccination, however, will ensure that the horse will not get as sick and will recover faster than if not vaccinated. 15

Vaccinate all young horses frequently and older horses regularly, particularly if there is an outbreak.  Use a modified live vaccine containing EHV 1 and 4, if possible.  If horses have never been vaccinated for EHV before, 1 to 2 booster shots are recommended at 4-6 week intervals after the first dose.  Foals should have their first dose at 4 months of age.  Since immunity only lasts 12 weeks, one EHV 1+4 vaccine should be given every 3 months for optimal protection and for young horses in higher risk environments (racehorses in training would fall into this group), though the minimum recommendation is every 6 months.11,16,17

Vaccinate pregnant brood mares at 5, 7, and 9 months of gestation with an inactivated vaccine that contains only EHV-1, preferably at high antigenic levels.  Pneumabort K, which is available in New Zealand, and Prodigy are two brands to consider.

There is very little evidence that vaccination can specifically prevent the neurological form of the disease, but recent studies have found that modified live vaccines can reduce the “viremia” and this may reduce the likelihood that the central nervous system of the horse will be affected.18

It has been noted that EHV types 1 and 4 are fairly consistent and antigenically stable,19 so unlike influenza viruses that mutate regularly, the same strains of EHV 1 and 4 remain basically unchanged over many years.  The implication of this is that vaccines need not be adjusted annually or for each outbreak to be effective.

It is important to understand that once horses are affected with Equine Herpes Virus, they can continue to be carriers for life.  At times of stress, they may begin to spread the virus around in their environment and infect susceptible horses around them. As a result, it is worthwhile to vaccinate young horses regularly to reduce the likelihood that they will become infected and then become silent carriers, even if there are no reports of a serious outbreak.

References

1.    Viel, 2009. A New Understanding of Equine Inflammatory Airway Disease, OVMA Conference Proceedings, 2009.
2.    Bailey, 1988. Wastage in the Australian Thoroughbred Industry)
3.    Allen, GP, 2002. Epidemic Disease Caused by Equine Herpesvirus-1: Recommendations for Prevention and Control, Equine Veterinary Education, 2002.
4.    Bryans, JT & Allen, GP. 1989. Herpes Viral Diseases of the Horse, Herpesvirus Diseases of Cattle, Horses and Pigs, edited by Wittman, G.
5.    Crabb, BS. & Studdert, MJ, 1995. Equine 86 Herpesviruses 4 (Equine Rhinopneumonitis Virus and 1 Equine Abortion Virus,  Advances in Virus Research, 45, 153–190.
6.    Allen GP, JH Kydd, JD Slater and KC Smith. Equid Herpesvirus 1 and Equid herpesvirus 4 infections. Infectious Diseases of Livestock, (Ed.) JAW Coetzer and RC Tustin. Oxford Press (Cape Town), Chapter 76, pp 829-859, 2004.
7.    Ostlund, EN, 1993. The Equine hHerpesviruses. Veterinary Clinics of North America, Equine Practice, 9, 283–294.
8.    McBrearty, Thesis, 2011.
9.    Dunowska, M, Wilks, R, Studdert, MJ, and Meers J, 2002. Equine Respiratory Viruses in Foals in New Zealand, NZVJ, 50, 140-147.
10.    Dunowska, M, Wilks, R, Studdert, MJ, and Meers J, 2002. Viruses associated with outbreaks of equine respiratory disease in NZ, NZVJ, 50, 132-139.
11.    Townsend, H and Morley, P, 1992.  Western College of Veterinary Medicine, Department of Large Animal Internal Medicine, lecture notes.
12.    Allen GP, JH Kydd, JD Slater and KC Smith. Equid Herpesvirus 1 and Equid herpesvirus 4 infections. Infectious Diseases of Livestock, (Ed.) JAW Coetzer and RC Tustin. Oxford Press (Cape Town), Chapter 76, pp 829-859, 2004. 13.
13.    D.P. Lunn et al – EHV-1 Consensus Statement J Vet Intern Med 2009;23:450–461
14.    Iverson, J, 1992. Western College of Veterinary Medicine, Department of Veterinary Epidemiology, Lecture Notes.
15.    Patel, JR, Foldi J, Bateman H, Williams J, Didlick, S, Stark R.   Equid Herpesvirus (EHV1) Live Vaccine Strain C147:  Efficacy Against Respiratory Diseases Following EHV Types 1 and 4 Challenges.  Veterinary Microbiology vol 92, Issues 1-2, 20 March 2003, pg 1-17.
16.    Hines, M.  Department of Veterinary Clinical Services, Washington State University,  Recommended Vaccinations for Washington Horses, 2001.
17.    AAEP website, 2001.
18.    University of California Davis School of Veterinary Medicine,  EHV-1 Vaccination Fact Sheet.
19.    Allen, GP & Bryans, JT, 1986. Molecular Epizootiology, Pathogenesis, and Prophylaxis of Equine Herpesvirus-1 Infections. Progress in Veterinary Microbiology and Immunology, 2, 78–144.
20.    Perkins, NR, Reid, SW, And Morris, RS, 2004. Profiling The New Zealand Thoroughbred Racing Industry, NZ Veterinary Journal 53, 69-76.

08 May

Twenty years ago, stomach ulcers in horses were not a commonly reported problem and veterinary texts listed them only as an infrequent finding in sick foals. Today, they are reported to occur in anywhere between 60 and 90% of standardbred racehorses and 50 to 60% of show ponies, stabled yearlings, eventing and dressage horses. The only group of adult horses free of ulcers are those on pasture 24 hours a day.

Pastured horses have a very different diet to stabled horses – and diet has been shown to contribute to ulcers. Under natural conditions, horses graze for around 16 hours per day. The stomach has adapted to a constant intake of grass by constantly secreting acid (for around 45 minutes per hour). The acid is buffered by saliva, which is produced during chewing and has a very high content of bicarbonate and mucus. The number of chewing movements and the amount of saliva produced varies with the type of feed. One kilogram of hay requires over 3000 chewing movements and results in the production of over four litres of saliva. One kilogram of grain requires only one third as much chewing and yields only two litres of saliva. The sign of an acid stomach is chewing of bedding, wood etc – the chewing process stimulates the flow of saliva, which in turn lowers stomach acid levels and the horse feels more comfortable – a bit like chewing an antacid tablet.

Stabled horses spend an average of four hours a day eating – compared to 16 hours for pastured horses. When chewing time and hence saliva production are reduced, stomach acid levels rise, increasing the risk of ulcers. High acid levels are a result of modern feeding practices: the amount of roughage, feeding frequency and type of feed have profound effects on stomach acidity. If the stomach sits empty for a prolonged period, the acid is not buffered by the food and saliva and the stomach will empty less frequently, allowing the acid fluid to remain in contact with the lining.

When feed is eaten rapidly, less saliva is produced and the sudden flow of a large volume of feed into the stomach causes a rapid increase in acid secretion. Both grains and pelleted feeds have been associated with increased risk. High grain diets favour bacterial growth and fermentation in the stomach. There is an increase in the number of bacteria that produce lactic acid and gas. Acid secretion increases in response to pelleted feed because pellets are eaten rapidly. Both weanling and adult horses consume pellets faster than they eat traditional grain diets.

Simply changing from pasture to hay and confining a horse to a stall can cause ulcers. Because hay is drier and coarser than grass, it can damage the lining of the stomach. Soaking hay for 6 hours will soften it and also reduce dust and airborne particles that irritate the respiratory system. In addition, any alterations in intestinal function may also be associated with stomach ulcers.  Insufficient blood flow due to worms can cause death of gut lining cells, resulting in slowing ulcer healing.

The most reliable way to produce ulcers in a horse is to provide insufficient roughage or to fast them. Multiple studies have demonstrated that periods as short as 12 hours without feed can result in low grade stomach irritation. Even beginning an exercise program results in more acid secretion by the stomach – making the provision of adequate roughage even more critical for the standardbred entering training.

Phenylbutazone or other anti-inflammatory drugs can also cause ulcers. The risk increases with long term use but can occur even after a single high dose. Phenylbutazone (bute) especially has an extremely low margin of safety and should only be used under veterinary supervision. A high salt intake can irritate or worsen pre-existing ulcers. To avoid excessive irritation, ensure that electrolyte intake matches need and give the daily dose with food.

Signs of stomach ulcers include poor performance, loss of appetite, poor condition and mild colic.  With the exception of mild colic, these symptoms can also be found in horses with a developing lameness, subclinical tying-up, a gut upset, electrolyte imbalances, sand ingestion and enteroliths.  However, loss of appetite for grain, signs of mild pain after eating, teeth grinding, salivation and belching are characteristic signs of stomach ulcers. While horses with a nervous temperament are thought to be more prone to ulcers, it is more likely that discomfort from stomach ulcers makes horses agitated and restless.

Horses with severe ulcerations and clinical symptom require treatment for at least 3 weeks. Around 20% of horses do not respond in that time and may need a different pharmaceutical or a spell. Horses with ulcers have notoriously poor appetites and may not have been eating all their medication if it was in the feed.  If dosed with it, poor technique could also lead to loss of some medication.  There is also a widespread problem with horses being given inadequate doses or not being dosed frequently enough, in attempts to save on the cost.

As few as 3% of moderate to severe ulcers heal without treatment in horses kept under conditions that predispose to ulcers. The only treatment that is 100% effective is to turn the horse out on pasture. Bear in mind also that the combination of poor appetite and alterations in gut pH, have negative effects that drugs cannot correct and supportive therapies, such as probiotics, should be considered. Even with improved appetite and weight gain, there can be a persistent mild dehydration, which can respond to combined probiotic/amino acid/electrolyte. Gamma oryzanol has been shown experimentally to have a protective effect on ulcer formation in several species, particularly ulcers induced by stress or fasting.

For less severe symptoms, and after the initial drug treatment, there are far less expensive therapies for continued treatment and prevention. Good results have been obtained with probiotics, gamma oryzanol, fermentation products, yeasts and digestive enzymes. These actives can be very effective in improving appetite, correcting diarrhoea and promoting weight gain. Some horses with ulcer-like symptoms that do not respond to anti-ulcer supplements respond extremely well to probiotics. In addition, under the guidance of your veterinarian, consider a special worming program for immature worm stages and for tapeworms.

In addition, not all gut symptoms are caused by ulcers and it is essential to have a veterinary assessment to rule out other causes of reduced appetite, weight loss and discomfort. Following a clinical and/or endoscopic examination, the various ulcer treatment options can be assessed.  Because of the major drawbacks of treatment –  cost, contravention of the Rules of Racing and recurrence of ulcers once treatment stops – long-term prevention with gamma oryzanol or another protectant, is advisable. Preventatives and treatments include good quality aloe vera juice, chlorophyll, gelatin kaolin, apple pectin, aluminum and calcium-based antacids, however, long-term use of compounds containing aluminium has been associated with toxicity.

The following feeding management practices can reduce the risk of ulcer formation:

  • Avoid prolonged periods of fasting – ulcers have been shown to develop within 10-12 hours when horses have no access to feed – ensure roughage available at all times
  • Feed on the ground – horses chew and swallow more efficiently when their heads are down and the throat extended. Feeding above the ground also results in abnormal movement of the lower jaw and unnatural patterns of chewing and teeth wear.
  • Feed frequent small meals – optimum is 4 times a day and not more than 2 kg of grain per feed.
  • Use steam-extruded grains and feeds which have been processed in such a way that eating is slower, resulting in more chewing, increased saliva production and higher saliva bicarbonate levels.
  • Deworm regularly with the correct compound.
  • Include probiotics and protectants such as gamma oryzanol in the daily diet.

By Dr. Jenny Stewart  BVSc BSc PhD MRCVS
Equine veterinarian and Consultant Nutritionist

07 May

Equine Herpes Virus

Equine Herpes Virus is the most common cause of upper respiratory infections.

Clinical signs of EHV infection include a fever, runny nose, runny eyes, cough, sores in the nose, depression, loss of appetite, and swelling in the legs.

EHV can occasionally cause a neurological disease characterised by various degrees of weakness, inability to get up or stand, and even death.

EHV is also a cause of abortion in mares.

There are several different types of EHV. Type 4 causes most of the respiratory disease; type 1 causes virtually all of the abortion and some of the respiratory disease; and many types can cause the nervous system symptoms.

Vaccinate all horses except pregnant broodmares with a modified live EHV-1+4 vaccine (Duvaxyn) every three months to maintain good immunity.

At a minimum, vaccinate every 6 months. Vaccinate pregnant mares at 5, 7, and 9 months of gestation with a killed EHV-1 vaccine (Pneumabort K +1B) to prevent abortion.

Tetanus

Tetanus causes “lock jaw” and death

Tetanus is caused by a clostridial bacteria that lives in the soil

It infects animals with deep wounds

Vaccinate in the neck muscles once a year or if animal gets a deep wound.

Do not use the vaccine that combines strangles with tetanus. You will get a much higher rate of site reaction.

Strangles

Strangles is caused by a bacteria, Streptococcus Equi

It is characterised by swollen, abscessed lymph nodes, thick green nasal discharge, difficult breathing, and even death in severe cases

“Bastard strangles” involves abscesses in the chest, abdomen, or legs. These abscesses may remain for months causing severe weight loss and ill health for extended periods of time. When they eventually rupture, the animal may die.

Vaccinate in the large muscles at the back of the back legs if possible as this reduces the possibility and severity of site reactions.

Repeat every 6 months for good protection.

As this vaccine has a higher rate of reaction, many people choose to vaccinate only when there is an outbreak of the disease in the area.

A Strangles vaccine is less likely to cause a reaction if it is given alone rather than in combination with any other disease antigen in the same vaccine.

A new intra-nasal vaccine (Pinnacle) has become available in New Zealand. This has been used for several years in North America and is effective while eliminating the site reactions that were common with the injectable versions.

07 May

Any time you put a needle in a joint you run the risk of creating an infection in the joint.  This is a very serious complication that requires aggressive treatment, at best, and can mean the end of the horse, at worst.  Joint infections are, however, rare.  The possibility of this complication should be carefully considered and the implications understood.  By agreeing to continue with intra-articular medication you indicate acceptance of this risk.

Joint infections should be suspected if the horse becomes severely lame in the treated leg.  Infected joints will be hot and swollen.  If lameness worsens, a veterinarian should be immediately consulted.

Less significant complications can cause similar clinical signs, and should be reported. These problems are not serious, but can look alarming for a few days.  They should always be differentiated from an infection. Sole abscesses that have been lurking about in the foot can progress causing worsening lameness and swelling.  Swelling with only mild lameness can occur due to an inflammatory or hypersensitivity reaction.  Occasional horses will have a “healing reaction” in response to homeopathic treatments.

Joint injection is painful.  Although most horses show no ill effects, some are quite uncomfortable for a day or two. Two grams of Phenylbutazone may be given if that is the case.

It takes 24 hours for the joint to completely replace its synovial fluid, so the medication will remain in the joint for that period of time.   To ensure that horses are not asked to work while still in discomfort from their joint injections, I recommend that they be rested for at least 24 hours following treatment.  It is not necessary to confine them to a box, but they should not be worked during this time.  Ideally, treated horses should do only light work for the first day or two after their rest period is over.  By the fourth day after injection, they can go back to their normal work schedule.

07 May

It has been reported that about 90% of poor performance cases can be attributed to lameness, either clinical (obvious lameness) or sub-clinical (lameness not readily visible under normal exam conditions).

It is logical that noticeable lameness causes horses to perform below their potential, but sub-clinical lameness can be an even greater problem.  Clinical lameness can be quickly recognised, investigated, and corrected.  In horses with sub-clinical lameness, however, the disease process remains undetected and untreated.  It is allowed to progress, resulting in irreversible damage to the structure of joints, secondary lameness, muscle pain, behaviour problems, impaired performance and economic losses.

Early diagnosis and intervention can stop minor problems from deteriorating, preserving long term soundness and maximising performance.

Most of my clients present every horse in their stable, on a regular basis, for physical exams.  This enables the identification of subtle or sub-clinical problems.

Clinical Lameness

A horse is clinically lame if it has a visible limp or asymmetric gait.  It will try to lift its weight off the sore leg and place more weight on the sound legs.  A “head-nod” results.  (When the sore front leg hits the ground, the horse lifts its head up to shift weight to the back legs and off the sore front leg.  When the sound front leg hits the ground, the head nods down, loading that leg excessively.)  Sometimes, when a horse is very lame in a hind leg, the horse will nod its head down to shift weight onto the front legs and off of the hind legs. Sometimes, a horse with a sore hind leg will lift its pelvis higher on the lame side (called a hip-hike).

Lameness is only visible (clinical) when one leg is relatively more painful than the opposite leg.  Both legs can be sore, but as long as the pain is unequal, the horse will protect the more sore side and the head nod will be evident.  There are various degrees of clinical lameness ranging from an inconsistent or almost imperceptible limp to an inability to bear any weight at all on the affected leg.

Sub-Clinical Lameness

Sub-clinical lameness is lameness that you can not see under normal conditions.  Bilateral lameness, lameness in all four legs, and lameness that only manifests under extreme stress or speed is sub-clinical.

Bilateral lameness is often unapparent.  If a horse’s legs are equally sore, he will not favour one and will not limp.  Instead, he will shorten his stride, develop back or muscle pain, perform and below expectations. This could include the following:- “stopping” in the last part of a race, refusing jumps, making mistakes of stride in dressage tests, tie up, blowing after working, having a longer than normal recovery, or developing behaviour problems such as pulling, bucking, and rearing. Many horses just develop a poor attitude to work. “Bleeding” or Exercise Induced Pulmonary Haemorrhage and dorsal displacement of the soft palate (“flipping the palate”) are common presenting complaints.

Some lameness only shows up at high speed or under extreme stress such as in the last part of a race.  Some will manifest only with a rider or doing particular movements like flying changes or lateral work.  Some will appear on a lunge line or on particularly hard, soft, or irregular or unstable footing.  Some only present in the cart and not in-hand. Once again, these lameness cases are often presented for performance and behaviour problems, back, or other muscle pain.

Lameness in My Practice

In my practice, the majority of horses presented for lameness or performance problems have one or more of the following:

  1. Foot pain including sole bruises, abscesses and, corns
  2. Arthritis (joint inflammation)
  3. Tendonitis (a bowed tendon) or
  4.  Suspensory Desmitis.

Bowed tendons and suspensory desmitis present as clinical lameness and there is obvious pain, heat, and swelling.

By far, the most common sub-clinical lameness or performance problems involve joint and foot pain.  In many cases these conditions are both present.

Arthritis

Arthritis is a term that means “joint inflammation” (arth-joint, itis – inflammation).   Inflammation occurs in joints when they are placed under stress in excess of what they have adapted for.  This stress can be sudden and severe (stepping in a hole, taking a bad step on poor footing, or some other accident), or it can be repetitive and low grade (wear and tear).

Horses are designed for eating grass and running away from the occasional predator.  They are designed to land flat on their feet, load bones and joints evenly from side to side, and break over the middle of their toes. Unfortunately, not many horses have perfect conformation, perfect hoof balance, or work on perfect footing so stress is not distributed evenly.  They are not born readily adapted for repeatedly pulling a sulky or carrying a rider around a track at top speed or over jumps.  The idea behind training is to gradually increase the stress on a horse causing them to adapt to the work we expect them to do.  In short, training a young horse or training a more mature horse down to race after a spell is constantly placing their joints under stress they have not adapted to. Therefore, inflammation occurs on an on-going basis in most horses in training.

Joints are made up of the ends of two or more bones which are covered with cartilage and joined together by the joint capsule.  The joint capsule is lined by the synovial membrane.  This membrane is very important as it produces the synovial fluid (joint fluid) that lubricates, protects and nourishes the joint cartilage.  In a healthy joint, synovial fluid is thick like syrup.  It is replaced every 24 hours or so on an on-going basis.

Inflammation in joints begins with synovitis and capsulitis. In synovitis and capsulitis, enzymes are produced that breakdown joint fluid, making it thin and watery.  It no longer lubricates and protects the joint properly.  With a lack of nourishment and lubrication, the cartilage surface of the joint becomes abraded.  Over a more extended period of time, the sub-chondral bone (bone underneath the cartilage in the joint) begins to change.

Over time, then, synovitis and capsulitis will progress to sub-chondral bone disease and osteoarthritis.  This entire process is referred to as arthritis or degenerative joint disease (DJD).  X-rays only show bone, so relatively advanced DJD is the first stage that is reliably visible on radiographs.

It is much better to identify and treat joint problems before they are visible on radiograph. If inflammation is stopped, the synovial membrane will make new fluid that will remain thick and sticky.  If the breakdown of synovial fluid is the only damage that has occurred, a completely normal joint environment will be restored.  If the cartilage surface has been damaged, some treatments can provide repair, and a normal joint can be created.  Once bone has changed, however, it cannot be reversed.  Thick, healthy joint fluid will stop rough bones from rubbing together in the joint, and DJD will be arrested, but a truly normal joint cannot be restored.

Treatment

Since the primary goal of therapy is to stop inflammation and to stop the progression of degenerative joint disease, the treatment of choice in most cases is intra-articular cortisone.  Cortisones are very effective anti-inflammatories, and remain the treatment of choice in human medicine for intra-articular therapy.

There are several different types of cortisone that can be used in joints.  Controlled studies have shown that all cortisones reduce inflammation and that most improve the health of joint cartilage. Triamcinolone (Vetalog, Kenalog, or Kenacort), Isoflupredone (Predef 2X), and Betamethasone (Celestone Soluspan) have all been shown to be safe or beneficial for joint cartilage. Methyl Prednisolone (Depo-Medrol or Vetacortyl) is likely safe in low doses, but can impair the healing of joint cartilage if given too frequently or in large amounts. Triamcinolone has been anecdotally linked to laminitis, but the relationship has not been confirmed.  It has never been caused in healthy horses at normal doses and has not been caused experimentally using doses up to six times those commonly used.

NSAIDS like Phenylbutazone (Bute) and Banamine tend to kill pain better than they reduce inflammation in joints, so they are not a sufficient treatment in most cases.

Once inflammation is resolved and DJD is arrested, the second goal of therapy is to restore a normal joint environment.  Hyaluronic acid (HA) is a building block for thick joint fluid, so supplementation may be useful.  HA can be administered directly into a joint, however, it does not work very well if there is a great deal of inflammation present and it is generally used in joints along with cortisone.    Studies have shown that IV HA (Hyonate or Legend) is as useful as intra-articular treatments, and recent research indicates that oral administration of HA may be helpful.

If cartilage damage has already occurred, then it can be beneficial to treat horses with a product that can stimulate joint repair or provide the building blocks for cartilage repair.  Adequan, Glucosamine Sulphate, and Pentosan may be used for this purpose.  Glucosamine Sulphate supplementation increases the body’s production of hyaluronic acid as well.

Additional medications are available to treat arthritis including some homeopathic treatments that reduce inflammation and stimulate joint healing.  The homeopathic medications I mainly use are Traumeel and Zeel.

Finally, the third goal of therapy is to prevent reoccurrence of lameness.  Adequan, Glucosamine, or Pentosan can be given regularly to reduce inflammation and repair cartilage.  They can keep inflammation at bay in sound horses in training, and they can increase the interval between joint injections in horses with lameness problems.  Optimal shoeing and good footing are of utmost importance, and adjustments to the training regimen may be helpful in some cases.

Summary

  1. The products of inflammation are enzymes that damage the joint.
  2. Early diagnosis and treatment will preserve normal joint structure and function maximizing long term soundness and performance.
  3. The first goal of therapy is to stop inflammation and, therefore, to stop the progression of degenerative joint disease.
  4. The second goal of therapy is to restore the most normal joint environment possible.
  5. The third goal of therapy is to prevent re-occurrence of the problem.

Dr.Corinne Hills

07 May

Tying up (Exertional Rhabdomyolysis) is a common cause of poor performance in racehorses and performance horses of all types.  It is a syndrome with a variety of causes, but always involves the breakdown of muscle cells which in turn causes a serious, easily recognisable clinical condition involving muscle stiffness, pain and a reluctance to move.  Sub-clinically, it can cause poor race performance or may present as a lameness problem.

I did up a basic outline of the condition and its treatments about 15 years ago for one particular client and one particular horse.  Since then, I have sent the information out to countless others, and they have in turn passed it on.  I have been told by many people who have read this that it was helpful to them, so here it is. Please keep in mind that this is my own interpretation of the papers I have read, cases I have seen, and thoughts on the subject from other veterinarians and horsemen.  Your own veterinarian may or may not agree.  Some of the information is well documented and widely published.  Some is not.  I have not referenced any of this as I did not originally prepare the paper for general review, but only for individual clients with specific horses.  I hope it gives you something to think about, but please consult with your veterinarian regarding your own particular situation.

Clinical Signs of Tying Up

  • Shaking, sweating, stiffness, reluctance to move
  • Can look like a colic or laminitis
  • Poor performance in races or competition
  • Dark urine

Diagnosis of Tying Up

Clinical Signs
As Above

Blood Test
The muscle enzymes, Creatine Kinase (CK) and Aspartate Transaminase (AST) (and LDH in some places) are checked in serum samples (red topped blood collection tube).
CK is an enzyme that goes up quickly and down quickly (It starts to go up in a couple of hours and peaks in about 24 hours).  AST is an enzyme that goes up slowly and down slowly (It goes up in a day and back down in a week).
If CK is elevated and AST is normal, the muscle cell damage has occurred in the last few hours.  The AST has just not had a chance to rise yet.  If the AST is high and the CK is normal, that indicates that a tie-up is resolving.  The CK has gone back down to normal, but the AST has not yet had enough time to recover.  If a tie-up is on-going, both the CK and AST would remain elevated

Causes of Tying Up (or predisposing factors)

A)   Lactic Acid Damage – lactic acid is a product of the metabolism that occurs in muscle cells when they are reaching the end of a race, or when a lot of energy is stored in muscle cells and then burned off quickly

  • Too much feed or soluble carbohydrate in the feed
  • Not enough work
  • Lameness – lame horses move differently to protect sore areas.  This makes certain muscles work much harder as well as inefficiently.  This results in greater lactic acid accumulation and muscle cell damage

B)  Calcium Insufficiency – calcium is important for the normal contraction of muscle cells.  In some horses, that mechanism requires more calcium than average (apparently this is more common in exceptionally good horses)

C)  Hypothyroidism – the thyroid gland doesn’t work as well as it should, and the horse is deficient in thyroid hormone.  A blood test can identify hypothyroidism

D)  Exposure to a Virus – recently, I have noticed in the literature references to tying-up in relation to exposure to Equine Herpes Virus (Rhinopneumonitis).  I don’t know the mechanism behind this, but will update this at some point when I do.

E)  Muscle cells not properly Hydrated (not bathed in enough fluid)

  • Dehydrated (HCT or PCV above about 0.45 or 45%)
  • Not enough electrolytes or an imbalance in electrolytes or minerals
  • Fillies and mares lose more electrolytes in their urine (especially when they are in heat) compared with geldings and stallions.

Treatment of Tying Up:

A)  Reduce Muscle Enzymes in Blood

  1. Administer additional electrolytes (1 cup) and salt (handful) with water (2-3 litres) via stomach tube.  This will cause the horse to drink more water and produce more urine.  This will help to clear the high levels of muscle enzymes while protecting the kidneys (which can be damaged by myoglobin which is released when muscle cells are damaged)
  2. Anti-inflammatory
  • Tube with Dimethyl sulfoxide (DMSO) – 1 cup or 250 ml this has a 7 day withdrawal, ½ cup or 125 ml has a 4 day withdrawal (you can put 110mL in an IV electrolyte jug) this is a great anti-inflammatory and will help get the muscle enzymes back to normal
  • Give Phenylbutazone (Bute) for the first day or so (7 day withdrawal for iv)
  • Give Dexamethasone – 50 mg IV.  This is a steroidal anti-inflammatory where as Phenylbutazone (Bute) is a non-steroidal.  This means that they work by different mechanisms, so their effects will be additive.  Also, Dexamethasone may help decrease the GGT.  If GGT is much over 20-30, horses will not race well.  This is really an indicator of stress, and I don’t really know the mechanism by which it affects racing performance, but it certainly can indicate poor performance.    For some reason, the metabolites of DMSO (the things it is broken down to by the body) can result in a higher GGT.  This does not appear to be related to impaired race performance.  I don’t have a good scientific understanding of this.  Maybe I will add a discussion of GGT to this someday…

Prevention of Tying Up:

  1. Anatest – 5cc IM every 2weeks – this messes up the hormonal cycle in fillies, so they shouldn’t lose so many electrolytes in their urine.  I don’t have any idea why progesterone (in Regumate) doesn’t work as well for this, but it doesn’t seem to.  In New Zealand, you cannot use Anatest, so you must make do with progesterone.  Hydroxy-P 500 is no longer allowed in NZ either.
  2. Electrolytes – increase daily electrolyte supplementation in feed – try doubling recommended levels.  This will ensure that the horse has sufficient electrolytes available.  They will urinate out the excess anyway, but will keep what they need.  Also, a small handful of regular table salt each day will increase water consumption.  Dunstan “all-you-need” contains about 3-10 times the electrolytes contained in most feeds.  Switching your concentrated feed to Dunstan “all-you-need” will provide all the electrolytes you require.
  3. Chromium – chromium has many effects, but for racehorses, its best effects are on muscle cells.  Chromium ensures that muscle cells are bathed in more fluid and electrolytes.  It protects muscle cells from lactic acid accumulation and the damage that results from it.  (i.e. finish races better with decreased lactic acid at the end, and prevents tying up)  It also acts as a natural anabolic, causing the horse to put on more muscle than fat.  It makes insulin work better, so anything insulin is involved in will be affected by chromium (I.e. it helps boost the immune system).  Only certain forms of chromium are useful, and the one from Nutritech (Altech), Biochrome, is the best.  It is in a form that can be absorbed and used by cells well.  It is also very safe.
    Read the label on the tub.  You will need to use four times the label dose for the first two weeks, then you can cut it back to about two to three times.  That means you could feed 8 scoops (20g) every day for the next two weeks.  Then, feed 4-6 scoops daily after that.  Dunstan “all-you-need” contains Chromium.
  4. Vitamin E/ Selenium – generally, selenium is included in supplements as sodium selenite.  This is an inorganic form, and some horses are not able to absorb it or use it that well.  If you are continuing to have problems, you can feed a yeast-based selenium.  It is in an organic form that cells can easily absorb and use.  It is put out by Nutritech (Altech) as well.  Dunstan “all-you-need” contains yeast based selenium from Altech.
  5. Keep your horse sound – have a lameness exam done, treat the significant problems, and treat with glucosamine regularly to repair any damage present in joints and to prevent the reoccurrence of problems.
  6. Calcium Supplementation – feed skim milk powder regularly.  It is in a good form for absorption.  The balance between calcium, magnesium, and phosphorus is important too.
  7. Baking Soda – you can feed baking soda so long as you stop a good 24 hours before racing.  Check with your veterinarian about the dose and when to stop.
  8. Traumeel – may be useful about an hour or two before training.  It is a good muscle anti-inflammatory as is herbal so it has no withdrawal time (but you are not supposed to give it on raceday, anyway).  Give it orally.
  9. Feed High Fat, Low Soluble Carbohydrate Diet – This is the most important way to prevent tying up.  The way you feed your horse is the most vital factor.  A really good study was done on quarter horses and thoroughbreds several years ago.  It showed that if you fed horses on a high calorie diet they were more likely to tie up than if you fed them a low calorie diet.  Obviously!  It also showed that WHAT you fed affected the incidence of tie-up.  If you fed a high calorie diet that was low in soluble carbohydrate and high in fat, you had a low incidence of tying up, while a high calorie diet that was high in soluble carbohydrates caused a lot of tying up.  Soluble carbohydrates are grains like oats and barley.  Insoluble carbohydrates are hays, grass etc.  In New Zealand, a great feed to try is Dunstan “all-you-need”.  In North America, a good feed to try is Purina’s Competitive Edge.  Both are high fat, low soluble carbohydrate, fully extruded feeds.  Feed them with free choice, quality hay or grass.  Dunstan “all-you-need” has the added benefits of MSM.  This is a derivative of DMSO, a great anti-oxidant and useful in the management of lameness, as well.
  10. Don’t feed them if they are not working – if you are giving your horse a day off, cut out the grain part of the ration.  Contrary to popular belief, they will not starve to death if they do not get grain on Sunday if they are not working.  They will survive quite nicely on hay or grass.  If you are feeding Dunstan “all-you-need”, you can feed them as normally as it is low enough in soluble carbohydrate.
  11. Relax – Since nervous horses are prone to tying-up, it can be useful to treat with various things that relax the horse.  Ensure they are receiving adequate B vitamins—especially B1 (Thiamine).  Some amino acids are helpful with this as well.  Treatments like Modecate can be helpful (it is a human anti-psychotic drug that is in the same class as Acepromazine but acts for 3 months at a time).  As the FEI withholding time has increased to 90 days, Modecate is less useful.  In some racing jurisdictions, the withholding time is as little as 7 days, though, so check your local restrictions.

Dr. Corinne Hills, DVM
Equine Veterinarian & Nutritional Consultant