Resources - USA - Equine

  • March 2, 2017

    By Dr. Chris Morrow, DVM

    As equine practitioners, we use the word choke to describe an esophageal obstruction. This condition will present itself as a horse begins to exhibit signs of distress including the expelling of feed from …

  • January 17, 2017

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    As winter weather approaches, temperatures will begin to fall with the possibilities of rain, snow, ice, and wind. Because of these environmental changes, increased …

  • November 17, 2016

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    Nutrient requirements of the horse can change depending upon several factors related to the type, and weight of the horse, stage of life and level of activity. When …

  • October 10, 2016

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    The senior horse has become more prevalent in modern times due to the change in workload, and activity of horses in general compared to what was required of the horse many …

  • September 12, 2016

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    At one time, it was generally thought by the equine scientific community that horses could not digest and utilize fat at a rate that would be sufficient to contribute to …

  • August 8, 2016

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    Distiller’s Dried Grains with Solubles (DDGS) are the by-products produced from the manufacturing process of ethanol. These products have been readily available in …

  • July 18, 2016

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    As breeding season for mares comes to a close, many considerations should be taken into account so that a live, healthy foal can be produced in the springtime next year.  …

  • December 22, 2016

    By Matt McMillan, Ph.D., Equine Nutritionist, Hi-Pro Feeds

    While some equine enthusiasts haul their horses throughout the year, many more begin to look towards taking their horses down the road to their favorite equine event as …

  • April 14, 2016

    By Dr. Chris Morrow, DVM

    As a student of the horse it is evident that the species was evolved on varied grass diets.  They are designed to walk around foraging ready to run away from anything that would eat them.  The …

  • March 17, 2016

    By Matt McMillan, Ph. D, Equine Nutritionist, Hi-Pro Feeds

    For many years, feeding oats and alfalfa hay has been a very common diet for the working and performance horse.  However, with more and more research being conducted in …

  • January 29, 2016

    By Matt McMillan, Ph. D, Equine Nutritionist, Hi-Pro Feeds

    As any good scientist would say, the answer to this question is “It depends…”.  So what about starch?  It seems that starch is, and has been …

Kentucky Equine Research

  • Appetite Stimulation for Horses

    horse eating grain

    When a typically ravenous horse leaves grain in his bucket or doesn’t seem interested in hay, it is cause for concern and prompt veterinary examination. But not all horses are eager eaters; some are far pickier. It’s nearly impossible to force a horse to eat if he doesn’t want to, but there are some things that can be done to help stimulate the appetite of the more discriminating eater.

    A horse may lose its appetite for a number of reasons. A veterinarian will likely rule out any medical concerns, such as fever, colic, illness, pain, choke, or dental problems.

    Research has shown that ghrelin, a hormone that stimulates hunger, temporarily decreases after short-term, high-intensity exercise. In addition, about 90% of horses in active race training and about 60% of working pleasure horses have equine gastric ulcer syndrome, a condition that can cause a painful stomach and decreased feed intake. General stressors, including a change in environment, trailering, herd separation, and hot, humid weather, can all be factors in reduced appetite and low feed intake. Horses with gastric ulcers should be treated to heal the lesions and then given a proven supplement, like RiteTrac, to keep new ulcers from forming. (Australian horse owners should look for these supplement options.)

    If you find yourself with a picky eater despite no medical diagnosis, gradually transitioning your horse to a new feed will sometimes spark interest in food, according to Catherine Whitehouse, M.S., a nutritionist with Kentucky Equine Research (KER). “Have you ever eaten the same thing day in and day out? You’d get bored, and anecdotal observations suggest that some horses do, too. Slowly introducing a novel feed may encourage a horse to eat,” she said.

    Horses evolved eating several small meals throughout the day. If a horse doesn’t want to consume his entire ration in two daily feedings, breaking the meal up into smaller ones spread over several hours may encourage eating.

    In more chronic cases, a veterinarian may recommend appetite-stimulating medications, such as steroids. However, such medications often don’t work. Benzodiazepine derivatives (types of tranquilizers) can cause temporary increases in appetite, especially in anxious horses, but their use is generally not recommended due to potential negative side effects. Furthermore, B-vitamins are frequently given in effort to encourage eating, especially in ill animals, but the positive effects are anecdotal and scientific research on this practice is limited.

    Some simple management techniques can be useful for encouraging food consumption. In hot weather, providing a cool bath can help make a horse more comfortable, therefore encouraging him to eat. If a horse is in an intense exercise program, temporarily easing the amount and duration of work could help. Keeping a buddy close by, offering turnout, and minimizing environmental stressors can all help a horse feel less anxious, increasing the likelihood of eating.

    When a horse stops or reduces feed intake, a veterinarian should be consulted immediately. Check the horse’s environment for potential stressors, and break up meals into several small portions throughout the day.

    The equine nutrition professionals at KER can help ensure the horse’s diet stays balanced, preventing problems such as weight loss and nutritional deficiencies. Contact a specialist today.

    Category Headline Image: 
    horse eating grain from tub
    Article Type: 
    Pull Quote: 
    If a horse doesn’t want to consume his entire ration in two daily feedings, breaking the meal up into smaller ones spread over several hours may encourage eating.
    Overview: 
    It’s nearly impossible to force a horse to eat if he doesn’t want to, but there are some things that can be done to help stimulate the appetite of the more discriminating eater.
  • Protecting Horses from Equine Herpesvirus-1, EHM

    sick horse

    Instead of developing an upper respiratory tract infection when exposed to equine herpesvirus-1 (EHV-1), some horses suffer abortions or a neurological condition called equine herpesvirus-associated myeloencephalopathy (EHM). Due to the devastating consequences associated with EHM, researchers* are focusing on how exactly the virus harms the central nervous system.

    “One of the prevailing theories at the moment involves the virus disturbing the blood supply to the delicate tissues of the central nervous system,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER).

    To be more precise, EHV-1 infects a specific organism called a peripheral blood mononuclear cell, or PBMC, that circulates in the bloodstream. Infected PBMCs ultimately circulate within the small vessels of the central nervous system, especially those located in the spinal cord. Coming into close contact with the cells lining the blood vessels and central nervous system allows the virus to compromise the blood supply in that area. As a result, circulation to that region of the central nervous system decreases, causing damage to the sensitive tissues due to lack of blood flow.

    According to various research groups, anti-inflammatory drugs could stop EHV-1 from negatively affecting the cells lining the blood vessels within the central nervous system. One group* recently tested various anti-inflammatory drugs in a laboratory setting and confirmed that they were able to decrease infection of those cells, protecting horses against EHV-1.

    Tested medications included acetylsalicylic acid (aspirin), lidocaine, firocoxib, flunixin meglumine, and dexamethasone. Each medication decreased the ability of EHV-1 to infect cells associated with the blood supply of the central nervous system.

    “This research was performed in a laboratory setting, and still needs to be tested further in live animals before veterinary recommendations can be made. In the meantime, other anti-inflammatory agents such as omega-3 fatty acids may also help protect horses against viral infections, especially EHV-1 that can cause EHM,” suggested Crandell.

    EO•3 has natural anti-inflammatory properties and is used to help support respiratory, reproductive, and musculoskeletal health. EO•3 supplies both EPA and DHA in a palatable oil that is top-dressed onto the feed.

    *Goehring, L.S., K. Brandes, L.V. Ashton, et al. Anti-inflammatory drugs decrease infection of brain endothelial cells with EHV-1 in vitro. Equine Veterinary Journal. In press.

    Category Headline Image: 
    sick horse
    Article Type: 
    Pull Quote: 
    One group recently tested various anti-inflammatory drugs in a laboratory setting and confirmed that they were able to decrease infection of those cells, protecting horses against EHV-1.
    Overview: 
    When exposed to equine herpesvirus-1 (EHV-1), some horses suffer abortions or a neurological condition called equine herpesvirus-associated myeloencephalopathy (EHM). Due to the devastating consequences associated with EHM, researchers are focusing on how exactly the virus harms the central nervous system.
  • Ditch the Itch: Saving Your Horse's Skin

    horse itch

    Few horses are immune to the occasional itch, but some horses are prone to severe itching and subsequent scratching.

    Major causes of itch include gnats, flies, and biting midges, also known as Culicoides. Some horses are allergic to bites and have an extreme reaction. Unfortunately, it is not possible to completely get rid of flying pests. Therefore, avoidance techniques and environmental management are important.

    Certain plants, as well as dust and mold particles from bedding and hay, potentially stick to and irritate the skin, especially if the horse gets sweaty. Removing offending plants, wetting hay, or altering bedding can help minimize irritants.

    Tools for the fight. Shade and physical barriers are essential for skin protection. Lightweight, light-colored fly sheets and masks are useful, but they should be kept reasonably clean. Dirt will attract more insects, and the combination of sweat and dirt can irritate sensitive skin. Commercial-grade fans will help minimize pests in stabling areas.

    Rinse a sweaty horse with water but avoid harsh detergents, which can remove the natural oils that provide a barrier of protection. Instead, use a mild shampoo for sensitive skin. A veterinarian should be able to suggest an appropriate shampoo for sensitive horses.

    Bug sprays have varying levels of effectiveness. Active ingredients in a spray should make up at least 2% of the total ingredients, so be sure to check labels. Water-based sprays are preferential to oil-based, the latter potentially creating an impervious barrier that can heat skin and aggravate itching. Keep an eye on your horse for any adverse reaction to bug repellents.

    Supplements, medication, and allergy shots. Omega-3 fatty acids, such as those found in EO•3, have anti-inflammatory properties and are potentially helpful for easing inflammation associated with itch and allergy. Although unlikely to cure the problem, omega-3s are a helpful part of sound nutritional support.

    A veterinarian will determine if medication is warranted to help break the itch cycle, or if allergy testing would be useful. Although allergy testing is not yet an exact science, it can be a valuable tool for treatment. Allergy treatment is individualized, and essentially “retrains” the immune system to reduce reactions to itchy stimuli, which takes time. Shots can take up to a year for maximum effectiveness, and even up to two years in severe cases, so patience is required.

    In conclusion, there is no one answer to solving the problem of the itchy horse. Multiple strategies are necessary, including decreasing exposure to trigger factors, managing the environment, and committing to long-term management.

    *White, S., and J. Wilson. 2016. The Itchy Horse. Table Topic Discussion at the American Association of Equine Practitioners 62nd Annual Convention, Dec. 3-7, Orlando, Florida.

    Category Headline Image: 
    horse itching
    Article Type: 
    Pull Quote: 
    Multiple strategies are necessary, including decreasing exposure to trigger factors, managing the environment, and committing to long-term management.
    Overview: 
    Few horses are immune to the occasional itch, but some horses are prone to severe itching and subsequent scratching. Therefore, avoidance techniques and environmental management are important.
  • High-Quality Milk Essential for Foals

    foal nursing

    Lactating mares provide the sole source of nutrition for newborn foals. As foals mature, they  begin to sample forage and even grain concentrates, and rely less on the dam’s milk. Providing nutrition to foals requires significant nutrient consumption. How do mares do it?

    Lactating mares produce approximately 2-4% of their body weight in milk each day. That means that a 1,200-lb (545-kg) mare will produce 24-48 lb (11-22 kg) of milk per day, equivalent to 3-6 gallons (11-22 liters). Her nutrient requirements are notably influenced by the amount of milk produced. While an average horse requires about 10 gallons of water per day, it is easy to see why a lactating mare requires 50-70% more water to support milk production.

    Peak milk production occurs during the first month of lactation, with only a slight decrease during the second month. In fact, milk production only decreases in volume slightly, to a low of about 2% of the mare’s body weight, over 5 or 6 months of lactation. The energy and nutritional value of milk declines more dramatically, however, as lactation progresses.

    By the fourth month of lactation, milk provides less than 30% of the foal’s energy needs. The foal has begun to consume creep feed and some forage by this time, gaining nutrition from these sources. When the foal is weaned, usually at 5 or 6 months of age, the mare will slowly stop milk production. The lack of stimulation of suckling and absence of the foal will cause the cessation of milk production and regression of the udder.

    According to Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER), “One of the major factors affecting a mare’s milk production is her nutritional status and body condition. Obese mares, with a body condition score (BCS) of 8 to 9, and thin mares, with a BCS of 4 or less, tend to produce less milk compared to mares with a more moderate condition of 5 to 7.”

    If a mare’s nutrient intake is above or below what her needs are, it doesn’t have much effect on the volume of milk production. If nutrient intake is less than what is needed, a mare’s body will draw on her own energy reserves to ensure that milk composition is sufficient for the foal. Over time, she may become deficient unless her nutrient intake is corrected and balanced. However, volume of milk is not typically altered based on varying intake of most nutrients.

    The most important thing to understand when feeding lactating mares is that their needs will change not only throughout their pregnancy but throughout the lactation period as well. In the first month or two of lactation, a mare’s needs increase, on average, to 50% or more above her maintenance needs, especially for energy, protein, calcium, and phosphorus. This is usually equivalent to between 2-3% of her body weight in feed per day. These needs slowly decline until weaning.

    Catherine Whitehouse, M.S., a nutrition consultant with KER, recommends a forage-based diet with the addition of concentrates as needed. “Select high-quality forage and, if necessary, a concentrate feed specifically designed for broodmares and growing foals. Low-quality, all-purpose feeds will not contain all of the nutrients mares and foals require, so it’s prudent to choose feeds appropriate for breeding horses.”

    Monitor the mare’s body condition to ensure she doesn’t lose or gain too much weight. Aim to keep her in moderate body condition. As always, any increases in feed volume should be done slowly to minimize risk of digestive upset.

    A KER nutrition advisor can help you ensure a mare’s diet is balance to support her own needs along with that of her foal. Start a consultation now.

    Category Headline Image: 
    foal nursing
    Article Type: 
    Pull Quote: 
    The most important thing to understand when feeding lactating mares is that their needs will change not only throughout their pregnancy but throughout the lactation period as well.
    Overview: 
    Lactating mares provide the sole source of nutrition for newborn foals. Milk production requires significant nutrient consumption. How do mares do it?
  • Airway Disease in Sedentary, Asymptomatic Horses

    equine respiratory health

    Diagnosis of certain airway problems in horses remains challenging for veterinarians. To determine if common diagnostic tests are related to lung function, researchers recently studied a group of sedentary, asymptomatic horses.

    Veterinarians use a roster of criteria to determine if a horse suffers from inflammatory airway disease, or IAD, which can be loosely defined as nonseptic inflammation characterized by the presence of mucus on endoscopy, inflammatory changes in bronchoalveolar lavage fluid (BALF), or pulmonary dysfunction, including coughing. Little information is available regarding the correlation between BALF and pulmonary function testing (PFT) in horses.

    In this study, 38 horses underwent PFT and histamine bronchoprovocation with flowmetric plethysmography to diagnose IAD. Bronchoalveolar lavage was performed 1 to 5 days after bronchoprovocation. Bronchoalveolar lavage is a procedure in which a bronchoscope is passed through the nose and into the lungs. Fluid is then squirted into the lung and recollected for microscopic examination.

    Of the tested asymptomatic horses, 52% were diagnosed with airway hyperreactivity. BALF cytology revealed, on the other hand, that 95% of horses had IAD. The number of horses in this study with IAD, as evidenced through hyperreactivity and BALF cytology, was greater than researchers anticipated, given that none of the horses showed sign of the disease, though no background information was given on the management of the study horses. Because of this, the researchers questioned the prudence of using invasive lung tests on horses without any symptoms and encouraged further investigation in horses with historical and clinical signs of the disease.

    Because of its anti-inflammatory properties, omega-3 fatty acids have been found to help horses with airway disease. Dietary supplementation of the omega-3 known as docosahexaenoic acid (DHA) can be an effective therapeutic approach when coupled with a low-dust diet to reduce airway inflammatory symptoms. Supplementing with marine-derived sources, such as EO•3, means the horse is directly receiving the long-chain omega-3 fatty acids DHA and EPA (eicosapentaenoic acid). Supplementation with plant-based sources (flaxseed, for example) require the conversion of short-chain fatty acids (ALA) to EPA and DHA. This conversion is thought to be inefficient in the horse.

    *Cullimore, A.M., C.J. Secombe, G.D. Lester, and I.D. Robertson. 2016. The relationship between bronchoalveolar lavage fluid cytology and airway hyperreactivity in a population of sedentary horses. In: Proc. 38th Bain Fallon Lectures. Equine Veterinarians Australia, p. 17.

    Category Headline Image: 
    respiratory health in horses
    Article Type: 
    Pull Quote: 
    Because of its anti-inflammatory properties, omega-3 fatty acids have been found to help horses with airway disease.
    Overview: 
    To determine if common diagnostic tests are related to lung function, researchers recently studied a group of sedentary, asymptomatic horses.
  • Importance of Detraining Programs for Athletic Horses

    horse in stall

    Appropriate training to ensure a horse’s fitness requires much time and energy. But what do you do if your horse needs a break during training or competition? The concept of “detraining” isn’t often considered, and how best to approach a detraining schedule remains unclear to many trainers and riders.

    Detraining simply refers to a reduction in the regular training schedule. Such breaks occur for various reasons, such as acute or chronic injuries, psychological or behavioral issues, or the need for additional rehabilitation.Detraining is associated with a decrease in fitness, as assessed using various physiological parameters, including:

    • Maximal rate of oxygen consumption (the more fit a horse, the more oxygen it consumes);
    • Maximal cardiac output and stroke volume (hearts of fit horses can eject more blood per contraction than unfit horses); and
    • Maximal heart rate, which is the most number of times the heart can beat under physical stress (fit horses have higher maximal heart rates).

    While some circumstances, such as sudden tendon injury or bone fracture, do not permit gradual detraining schedules, others do. Behavioral issues necessitating a break from a demanding training schedule or perhaps a flare-up of a musculoskeletal issue may allow riders to back off from training slowly.

    According to one study*, being able to maintain some level of exercise during rehabilitation maintained fitness better than horses that were only hand-walked or on complete stall rest. Specifically, horses still able to canter lightly for merely three minutes a day, five days a week, maintained higher performance variables, including maximal heart rate.

    The researchers concluded, “These results suggest that it might be possible to identify a minimal threshold exercise intensity or protocol during detraining that would promote maintenance of important performance-related variables.”

    In other words, devising detraining protocols tailored to specific medical and psychological conditions would not only allow time for healing but also maintain athletic fitness to facilitate return to training.

    “Even horses in detraining benefit from advanced nutritional support to maintain condition, electrolyte status, and musculoskeletal health. Restore SR helps replenish valuable electrolytes. This slow-release formula allows horses to absorb the electrolytes over time for sustained absorption,” recommended Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER). Australian horse owners should look to Restore or Endura-Max. For supporting joint health, consider KER•Flex and Synovate HA. In Australia, choose Glucos-A-Flex.

    While the benefits of slow detraining were noted in this study, many injuries require stall rest, which can affect bone strength due to demineralization. To avoid this, look for DuraPlex, a bone mineralization supplement that helps maintain healthy bone metabolism during layup. Bone Food is available in Australia.

    *Mukai K, Hiraga A, Takahashi T, et al. 2017. Effects of maintaining different exercise intensities during detraining on aerobic capacity in Thoroughbreds. American Journal of Veterinary Research. 78(2):215-222.

    Category Headline Image: 
    stalled horse
    Article Type: 
    Pull Quote: 
    Detraining simply refers to a reduction in the regular training schedule.
    Overview: 
    Appropriate training to ensure a horse’s fitness requires much time and energy. But what do you do if your horse needs a break during training or competition?
  • Feeding Horses in Low Body Condition

    thin horse

    Domestic horses depend on humans to supply them with life-sustaining feedstuffs. Unfortunately, some horses are not given access to enough forage and feed to maintain acceptable body condition and become extremely thin. Refeeding these horses can be challenging for even the most well-meaning caretakers.

    “All undernourished horses should be evaluated thoroughly by a veterinarian knowledgeable in starvation cases,” said Catherine Whitehouse, M.S., a nutrition advisor with Kentucky Equine Research (KER). “Not only will the examination identify immediate concerns, it will offer a baseline to gauge progress as refeeding advances.”

    Health concerns should be addressed, and any wounds or blemishes should be treated accordingly. Hooves should be tended to as soon as the horse is strong enough to be trimmed or shod comfortably and safely. If lameness precludes trimming and shoeing, check back with a veterinarian about pain management possibilities during hoof-care procedures, especially if the hooves have been neglected for a long period of time.

    Faced with an extremely thin horse, how does a caretaker begin refeeding? One refeeding schedule was proposed by researchers at the University of California, Davis, and has been used for many years*, according to Whitehouse.

    Days 1-3:  Feed 1 lb (0.45 kg) of leafy alfalfa (lucerne) every four hours (total of 6 lb (2.7 kg)/day in six feedings).

    Days 4-10: Slowly increase the amount of alfalfa and decrease the number of feedings so that by day six just over 4 lb (1.8 kg) of hay is fed every eight hours (total of 13 lb (5.9 kg)/day in three feedings).

    Days 10 and beyond: Feed as much alfalfa as the horse will eat and decrease feeding to twice per day. Provide access to a salt block. If the horse is progressing well in its recovery, small amounts of grain can be added at this point under a veterinarian’s supervision.

    “This schedule should be used as a guide. Slight changes based on the situation and availability of feedstuffs will also likely yield satisfactory results, as the key is to provide small portions of highly palatable and digestible forages,” said Whitehouse. “Certainly, if an owner is fortunate enough to have access to a veterinarian that is well versed in refeeding, follow that professional’s suggestions.”

    Caretakers might run into problems when refeeding a starved horse. Consider these points:

    • Watch the horse closely as he eats on the first day or two of refeeding, taking note of chewing and swallowing technique. Does the horse process the forage like a healthy horse? Problems with teeth might keep a horse from eating normally, and painful swallowing due to strangles, abscesses, or scar tissue from previous choking episodes can make a horse unwilling to consume forage. Contact a veterinarian if the horse shows little interest in eating, or if the horse rolls the forage in its mouth and then drops it. An examination by a dental specialist might also be a priority.
    • Think about treating the horse for gastric ulcers at a time approved by the horse’s veterinarian. “Gastric ulcers often develop because horses go long periods without eating. In the case of starved horses, days or weeks often elapse with little or nothing to eat, so gastric ulceration is a valid concern,” Whitehouse said. Gastric ulcers will sometimes reduce appetite, negating refeeding efforts. “Omeprazole can be used to heal ulcers, and then horses can be placed on a supplement such as RiteTrac, which will support a healthy gastric environment. RiteTrac also contains a buffering agent to optimize hindgut health,” she commented. (Horse owners in Australia should look for these research-proven products.)
    • If a horse becomes uninterested in alfalfa and appetite wanes, allow the horse access to lush grass for a few minutes several times a day, if possible. Green grass is a well-known appetite enhancer. Do not allow the horse to gorge on grass.
    • Changes in diet should always be made bit by bit, slowly decreasing one feedstuff while gradually increasing another. Be especially cognizant of this when refeeding starved horses, as their gastrointestinal tracts will not be primed for sudden variations in rations.
    • Malnourishment causes a host of inflammation processes to spike in horses. The addition of a body-wide anti-inflammatory, such as omega-3 fatty acids, could help multiple systems regain strength. “The most potent omega-3 fatty acids come from marine-derived sources, so choose a product such as EO•3 that is rich in DHA and EPA,” said Whitehouse.

    Horses provided the best of care sometimes lose weight as part of other, unrelated health problems, including kidney and liver disease, aftereffects of major surgery, neurological dysfunction, and gastrointestinal anomalies. Nutritional requirements for these horse differ slightly from those of starved horses. See Feeding the Atypical Horse for more information.

    *Stull, C. 2003. Nutrition for rehabilitating the starved horse. Journal of Equine Veterinary Science. 23:456-459.

    Category Headline Image: 
    thin horse
    Article Type: 
    Pull Quote: 
    Caretakers might run into problems when refeeding a starved horse.
    Overview: 
    Refeeding extremely thin horses can be challenging for even the most well-meaning caretakers. One refeeding schedule was proposed by university researchers and has been used for many years.
  • Potassium Imbalance: Hyperkalemia in Horses

    horse lying down in field

    Potassium is an electrolyte necessary for proper muscle function. Along with other electrolytes such as sodium and calcium, potassium plays an important role in normal muscle contraction and relaxation. However, when potassium concentration in the bloodstream gets too high, a condition known as hyperkalemia, it can be life-threatening.

    In healthy horses, the kidneys filter out excess potassium from circulation, which is then excreted through the urine. When the kidneys fail to clear potassium, or when too much potassium moves from inside to outside of cells, hyperkalemia can result. Abnormally high concentration of potassium in the blood causes muscles to contract more than they should, resulting in cramping and irregular heartbeat. At a greater risk of hyperkalemia are horses with a history of hyperkalemic periodic paralysis (HYPP), compromised kidney function, or massive cellular destruction, such as after trauma, burns, or a severe episode of tying-up.

    Classic signs of hyperkalemia include muscle weakness, trembling, depression, and lethargy. While these symptoms are fairly general, when accompanied by changes in cardiac rhythm, hyperkalemia should be suspected. Cardiac changes are not always present in cases of hyperkalemia, so the absence of cardiac abnormalities should not rule out such a diagnosis.

    Langdon Fielding, D.V.M., discussed treatment of hyperkalemia at the 2016 American Association of Equine Practitioners Convention in Orlando, Florida*. Intravenous (IV) calcium borogluconate (23%) in a five-liter bag of isotonic fluids is one treatment option. Administering calcium-containing fluid will not reduce plasma potassium concentration, but it can help protect the heart muscle against the negative effects of excessive potassium.

    The intravenous administration of dextrose (sugar) increases insulin concentration naturally. Insulin shifts potassium from outside to inside of the cell, consequently decreasing its concentration in circulation. Insulin itself can be administered intravenously in conjunction with dextrose, but Fielding noted that this technique should only be used when blood glucose can be closely monitored due to other risk factors.

    Beta agonists are a class of drugs that relax airway muscles. Like insulin, beta agonists drive potassium inside of cells. However, research is needed in horses as most of the relevant research on this topic has been conducted in other species. Diuretics may be administered to help increase the excretion of potassium in urine, though diuretics should not be given to dehydrated horses.

    Finally, sodium bicarbonate had previously been recommended to treat hyperkalemia, but clinical trials have shown little to no benefit, and should not be a primary treatment.

    Recognizing hyperkalemia can be a challenge. The horse’s health history is an important consideration, and if hyperkalemia is suspected, treatment should be initiated as soon as possible, with the horse monitored for signs of improvement.

    *Fielding, L. 2016. Review of the treatment of hyperkalemia in horses. In: Proc. 62nd American Association of Equine Practitioners Convention, Orlando, FL. pp. 225-227.

    Category Headline Image: 
    sick horse
    Article Type: 
    Pull Quote: 
    When the kidneys fail to clear potassium, or when too much potassium moves from inside to outside of cells, hyperkalemia can result.
    Overview: 
    Along with other electrolytes such as sodium and calcium, potassium plays an important role in normal muscle contraction and relaxation. However, when potassium concentration in the bloodstream gets too high, a condition known as hyperkalemia, it can be life-threatening.
  • Managing Heaves in Competition Horses

    horse heaves

    Veterinarians and horses owners can use several medications to help horses cope with heaves, including inhaled corticosteroids such as budesonide. Corticosteroids, however, are tightly controlled in many equine athletic events, and according to a recent study*, severity of heaves (recurrent airway obstruction, RAO) may impact reported budesonide withdrawal times.

    Barton and colleagues hypothesized that inflammation in the airway of horses suffering from RAO could alter the way budesonide is absorbed. Specifically, the researchers hypothesized that a combination of exercise and respiratory tract disease would increase the rate of budesonide uptake systemically, thereby prolonging the presence of drug residues in the body, blood, and urine. As a result, the recommended withdrawal times for budesonide might not be applicable to exercising horses with RAO.

    To test this theory, horses were administered budesonide and either left at rest or exercised. Blood and urine samples were subsequently collected 4-96 hours after budesonide administration and tested for budesonide-related metabolites.

    As suspected, all horses with RAO had significantly higher blood and urine concentrations of budesonide than non-RAO horses, and all RAO horses had budesonide concentrations exceeding the limit of detection at 96 hours. In other words, these horses would test positive at competition. Further, exercise increased systemic levels of budesonide.

    Together, these findings confirm the researchers’ suspicion that the interval between budesonide and competition should be increased beyond the currently accepted withdrawal time to avoid a positive test and elimination from competition. Unfortunately, this could mean that horses are competing with uncontrolled heaves, which will negatively impact their athleticism.

    “Budesonide and other inhaled medications provide immense relief to horses suffering from respiratory problems; however, management and dietary changes also should be made for maximal relief. This appears especially true for competitive horses that need to be weaned from their medications prior to an event,” advised Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER).

    “In addition, studies show the benefits of omega-3 supplementation, such as EO•3, for improving airway function in horses with airway inflammation.”  

    *Barton, A.K., H. Heinemann, U, Schenk, et al. 2017. Influence of respiratory tract disease and mode of inhalation on detectability of budesonide in equine urine and plasma. American Journal of Veterinary Research. 78:244-250.

    Category Headline Image: 
    horse heaving
    Article Type: 
    Pull Quote: 
    Further, exercise increased systemic levels of budesonide.
    Overview: 
    Researchers investigate whether inflammation in the airway of horses suffering from recurrent airway obstruction could alter the way budesonide, a corticosteroid, is absorbed.
  • Improving Intestinal Motility in Horses

    equine gastrointestinal tract

    Measuring 100 feet or more in the average mature horse, the equine gastrointestinal tract serves many functions, all neatly compartmentalized:

    • The mouth chops and grind feed and forage into manageable pieces;
    • The esophagus transports ingesta from the mouth to the stomach;
    • The stomach further breaks down ingesta into minute particles that pass into the small intestine;
    • Some types of nutrients in the feed, such as nonstructural or water-soluble carbohydrates, proteins, fats, vitamins, and minerals, are digested and absorbed in the small intestine;
    • The remainder of the feed, primarily structural carbohydrates or fiber, pass into the cecum and large intestine, where they are fermented to form volatile fatty acids, a primary source of energy for the horse.

    Any alteration in the proper functioning of this system can quickly become life-threatening. A large variety of disorders can decrease the ability of the gastrointestinal muscles to contract appropriately, delaying the movement of ingesta. Decreased motility, or hypomotility, can occur in cases of equine grass sickness, gastroduodenal ulceration, colic (e.g., obstruction, impaction, excessive wall distention, strangulating obstruction), inflammation of various regions of the gastrointestinal tract such as peritonitis, duodenitis, proximal jejunitis, and colitis.

    Drugs currently used in equine medicine to treat horses with hypomotility of the gastrointestinal tract are vast and varied, some more effective than others. Plus, many of the available drugs have important side effects to consider before administration.

    One promotility agent used in human medicine, prucalopride, was recently examined by equine researchers. Prucalopride works by a completely different mechanism of action than other promotility agents currently approved for use in horses. Prucalopride activates a serotonin receptor called 5-HT4. In human patients, oral administration results in rapid absorption of the medication and reportedly helps motility disorders of the esophagus, stomach, and intestine.

    Preliminary studies in horses* show that prucalopride appears to be safe and can effectively increase contractility of the duodenum, cecum, and colon following oral administration. Further research must confirm these findings; however, the researchers stated, “Prucalopride may be a useful adjunct to the therapeutic armamentary for treating hypomotile upper gut conditions of horses.”

    According to Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER), prevention of gastrointestinal disorders through proper nutrition and supplementation is always the best remedy.

    “KER’s dietary supplement RiteTrac supports total digestive tract health. The fast-acting antacids and coating agents quickly neutralize excessive gastric acid and contains EquiShure, a time-released hindgut buffer to minimize hindgut acidosis. Such a product might be particularly beneficial for horses prone to hypomotility disorders, colic, gastric ulcers, or hindgut acidosis,” recommended Crandell. In Australia, look for these proven products.

    *Laus, F., M. Fratini, E. Paggi, et al. 2017. Effects of single-dose prucalopride on intestinal hypomotility in horses: preliminary observations. Scientific Reports. 7:41526.

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    Any alteration in the proper functioning of the equine gastrointestinal tract can quickly become life-threatening, so it is important to ensure this system runs smoothly.