Ask The Vet: Racehorse Health - November 09

This is a timely question. A recent issue of Blood-Horse (Sept. 19, 2009) published an article (“Feeding for the Ages”), where I was interviewed about feeding the race horse through the various stages of growth and training. When a horse becomes a weanling there is a lot to consider. Now that the foal doesn’t have its mother’s milk to depend on for its nutrient needs we need to supply it. One of the most common mistakes we make is not feeding high enough concentration of various nutrients to provide for optimum growth. Since the weanling needs many of the same nutrients an adult horse does just with a smaller and shorter digestive track, we need to pick highly concentrated feeds to provide the same amount of nutrients, but with smaller amounts of feed.

Protein for example, is one nutrient that is needed in higher amounts than for mature horses. Some people think that too much protein will cause developmental problems; however, it is actually just the opposite. If weanlings do not get adequate protein in their diets, it could actually stunt growth and is more likely to cause the developmental problems. To get adequate protein for a weanling, alfalfa or an alfalfa/grass hay mixture should be used as the majority of the diet. Alfalfa, along with being high in protein, is also a good quality protein, so it will have the correct balance of the limiting amino acids that a growing horse needs (e.g. lysine and threonine). It is recommended for horses to eat about two percent of their body weight in dry matter (feed without the water content). Depending on the young horses’ weight, factor in about 1.5 percent of that being the good quality forage, and the remainder as a grain supplement.

The grain supplements should be a grain that is formulated for the young growing horse. Some may be called a mare and foal feed, which is also adequately balanced for the weanling and yearling. Calcium and phosphorus are other minerals that need to be in a specific ratio for the young growing horse. A 2:1 calcium to phosphorus ratio is best. This is easy to accomplish if there is alfalfa in the diet; alfalfa has about a 5 or 6:1 ratio, which is fine, however, under no circumstances should there be less calcium than phosphorus. An inverse ratio will cause the excess phosphorus to interfere with the absorption of calcium into bone.

Zinc, copper and selenium are also minerals that are needed in a particular balance, however, if the young horse is on good quality forage and a commercial grain supplement there is no reason to need to worry about any deficiencies here. Feed companies have already fortified their grain based products to provide adequate quantities. The only extra supplement that would be necessary is free-choice access to a plain white salt block.

The key to keeping the young horse healthy is really to monitor its body condition. Learning how to body condition score is a good idea and there are many on-line sites that can help provide you with a guide. However, weekly evaluations will help you determine if you are feeding adequate energy needed to maintain a healthy body condition. A quick and dirty rule is if you cannot see, but easily feel the horse’s ribs his nutrition is right where it needs to be. If you can start to see ribs or are unable to easily feel ribs you may need to increase or decrease the feed accordingly.

If maintaining a balanced diet, using these few guidelines, no other supplements should be necessary. However, as the horse grows and becomes a racehorse in training and actually starts racing, small changes may need to be made to increase the amount of energy in the diet, decrease some of the protein and balance of the various minerals. As always, it is best to work with a veterinarian that is comfortable giving nutrition advice or an equine nutritionist to properly balance your horse’s diet before making any drastic changes. Dr. Carey Williams, Rutgers, the State University of New Jersey, and Associate Director of Outreach at the Rutgers’ Equine Science Center.

There is really no discrepancy. Endurance horses racing for long distances at similar speeds as Pony Express horses don’t show EIPH. Bleeding appears to require intense bursts of speed and intense effort. Your wild horse observation may or may not be true. Distance isn’t the problem; speed is. Regardless, no one expected EIPH was so prevalent in race horses, barrel racers or polo ponies until systematic endoscopic examinations were performed. I don’t know if any studies have been attempted in wild horses; they would be quite a challenge. An easier approach may be to examine lung tissue from wild horses, which have died looking for tell-tale pathological changes in their lung tissue. Rick Arthur, DVM, Sierra Madre, Calif.

The simple answer is that it could be a sprain/strain (called synovitis), bone chips or something more significant. Considering her career as a racing Thoroughbred, one must consider the common ailments that are inherent to the sport. One of the most common injuries is carpal bone fracture. But, before we get ahead of ourselves on the specifics of prognosis and future usefulness, we must diagnose the ailment.

The accepted procedure would be to have your veterinarian examine the entire horse in a methodical fashion to determine if this knee is the only problem, since some injuries in racehorses are bilateral (especially knees) and some occur secondarily to primary injuries elsewhere in the animal. If the knee is the only problem, one approach would be to have your veterinarian diagnostically “block” the knee to see if the horse gets sound after injection. If so, radiographs are then used to confirm the diagnosis. Another approach would be to rely on physical exam findings and simply x-ray the knee. Radiographs will reveal the condition of the bones in her knee, and modern digital radiography will provide an instant depiction of the presence or absence of chips or fractures. Depending on the presence and/or location of the problem, recommendations for treatment will be made. Also keep in mind that speed may be of the essence because if surgical intervention is indicated, it is better to get it done before secondary arthritic changes develop in the joint.

If the radiographs are clean, the treatment for synovitis is medical, and best treated in the early stages before the development of degenerative changes. Hydrotherapy or ice is useful to minimize acute inflammation. Also, nonsteroidal anti-inflammatory drugs (NSAIDs) like Bute, Banamine, Ketofen or Equioxx can be used systemically, topical products like Surpass may be applied to the area, and joint injection with individual products alone or in combination would be of benefit. Discuss with your veterinarian the specifics regarding intra-articular products. There are many and the choice will likely be dictated by the future use of the horse.

In this case, let’s assume that the radiographs are not clean. Careful interpretation of the radiographs is crucial, and your veterinarian may want to review the films at his/her office rather than “on the spot” at the barn so that subtleties are not missed. I will offer some generalities here. Injuries, specifically chip fractures, in the radiocarpal (upper) joint tend to have a better prognosis than those in the intercarpal (lower) joint, presumably because the lower joint is believed to be more weight bearing than the upper, which works more as a hinge. The prognosis also depends on which carpal bone is involved, and whether a chip or fracture is displaced or not. Both sagittal (up and down) and transverse (across) slab fractures also occur in the intercarpal joint, most commonly in the 3rd carpal bone. These fractures can be more serious than chips and may require internal fixation via a screw. Since the swelling you describe is on the front of the knee to the inside, the injury probably exists in the radial carpal or 3rd carpal bone, both of which lie directly beneath the swelling.

To summarize, the future use of the horse will dictate your choice of treatment, but because of the numerous conditions that can occur in the knee, treatment cannot commence until an accurate diagnosis is made. Nicholas L. Meittinis, DVM, Managing Member Maryland Veterinary Group, LLC.

Thanks for the question! This is a question that I have received frequently over the course of my practice career both at the racetrack and in private practice off the racetrack.

Based on what you have described, I do not think you need to be concerned at the present time. The color and turbidity (thickness) of horse urine can be quite variable and is dependent on a number of factors including volume of urine, the concentration of urine and the presence of different substances that can find their way into the urine. Normal equine urine is typically clear to yellow in color and can be anywhere from transparent to cloudy in its consistency. Color and turbidity do not provide significant information on whether a disease state is present. Furthermore, the amount of urine voided can be quite variable between horses and can be influenced by the horse's hydration status, amount of water intake and behavioral factors.... some horses just prefer to go more frequently than others!

When a disease state is present in the urinary tract, the horse will exhibit signs both in their urination procedure and in the color and/or consistency of the urine. Things to look for include difficult or painful urination (dysuria), abnormally frequent urination (pollakiuria) and repeated attempts to urinate, often maintaining the urination posture for long periods of time. Also, the presence of blood in the urine (hematuria) is an indication of a problem in the urinary tract. Abnormally thick urine could also indicate the presence of mucus, blood, pigments or other compounds in the urine and may be an indication to seek veterinary assistance.

Should you witness any of the warning signs discussed above, it is time to call your veterinarian! The most common diagnostic tool used for urinary problems is the urinalysis. This test examines the urine for the presence of cells, blood and other compounds, which may indicate the cause of your horse's discomfort. This test, along with other blood tests and a thorough physical exam, is sufficient to diagnose most of the equine's urinary tract problems.

Most likely what is happening with your recently retired racehorses is an adjustment to a new environment, new diet, new daily routine, etc. Over time, your horses’ urination habits will most likely become similar to what you are used to.... but remember that these habits can be quite variable and you shouldn't get too worried unless you notice the aforementioned warning signs. Thanks again for your question. Bryan H. Young, DVM, Young Equine Services, Inc., Lubbock, Texas

Abnormal angle of the limb starting at the knee can lead to abnormal weight bearing during exercise. This can result in joint and foot problems that cause lameness later in life due the unequal load transmitted up one side of the limb.

If a foal weanling or yearling has an abnormal limb deviation (the lower part of the limb angles in or out from a straight line from the shoulder to the ground), which does not respond to normal foot trimming and restricted exercise, use of periosteal stripping may be helpful in mild deformities. If there is a significant deformity, which most often occurs with the limb angling out from a straight line from the shoulder to the ground, surgically placing a wire across the growth plate between two screws to inhibit the growth plate on the inside of the affected leg at the end of the radius will allow lengthening of the radius on the outside of the limb, thereby straightening the leg back to normal. This is best done between 3-6 months of age when the growth plate is rapidly adding new bone to the radius. Once the legs are straight, the screws and wire are removed. A single screw is sometimes used to bridge the growth plate to accomplish the same limb straightening. This is usually done to correct deviation of the limb inside the straight line from the shoulder. This is usually done in weanlings or yearlings. The screw is removed once the leg is straight.

This type of surgery is very effective if completed early in the growth phase (3-6 months). Some adjustment in the angle can be made with this technique from 6-20 months, though the corrections takes longer and depending on the amount of limb angulation it may not result in total correction. The surgery is successful if it results in a straight leg. Often horses will have a slight angle to the outside of the straight line from the shoulder (0-5 degrees determined by radiographs of the knee). If this is the case, no correction is necessary. Nat White, DVM, Dipl. ACVS, Marion DuPont Scott Equine Medical Center, Leesburg, Virginia.

Tieing up has always been associated with an electrolyte imbalance but is more likely due to varying levels of exercise and diet. Potassium levels are important but difficult to measure. The best treatment is to prevent the condition before it occurs through a consistent feeding plan and a consistent exercise program. Once a horse ties up, it is important to decrease the ongoing damage by running fluids to keep the kidneys functional. Banamine and dexamethasone are two medications I reach for at this time. BC2A paste is a good preventative and I recommend feeding KCL salt daily. Dantrium or acepromazine are medications that work to help prevent this condition. Continued problems with tieing up warrant more aggressive treatment and prevention. Foster Northrop, DVM, Northrop Equine, Louisville, KY.

Diaphragmatic hernias are rarely seen by us. They are usually caused by blunt trauma such as horses colliding on the track, sometimes kicks that are complicated by fractured ribs, or falls on the track. They are like most hernias in that the horse can do fairly well with the hole present but can start to experience problems when other structures such as loops of intestine start to become entrapped within the hole in the diaphragm. Therefore, signs observed would vary from increased respiratory rate to colic signs with or without toxicity due to degrading bowel. They certainly can be a life threatening situation at that point. Surgical repair would be required in this situation and the prognosis would depend on the amount of tearing and the degree of compromise to the gut. That's the bad side. Horses can and do live with chronic hernia, though, and may not show significant signs for years. As far as precautions to optimize health, I would recommend to keep the horse on a consistent diet and keep the exercise moderate. I don't know what plans you would have for this horse, but I would probably not look for this horse to be in strenuous activity. Jumping and eventing-type exercise might not be in his best interest. There are reports of stallions injuring their diaphragms during breeding, so that might be a risk factor as well.

Scott A. Hay, DVM
Teigland, Franklin and Brokken
Fort Lauderdale, FL