Noteworthy Research: 07/03

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Feed And Heart-Rate Recovery
New findings from a study at Warwickshire College in the United Kingdom, published in the Equine Veterinary Journal, suggest you need to strike a balance between high- and low-forage feeding for high-performance horses.

Horses were fed diets composed of varying levels of hay. Those fed 100% hay vs. those fed a 50% hay diet showed the expected increase in body weight, intestinal transit time and water consumption. More interestingly, however, the 100% forage horses also showed significant increases in the maximal heart rate during exercise and in the one-minute post-exercise recovery heart rate. They also had post-exercise body temperatures an average of 0.8?° Centigrade higher.

The conclusion is that high-forage feeding can be a problem for horses in strenuous sports. It’s a double-edge sword, though, as horses are designed to function on high-hay feeding, which results in the desired slowing transit time through the gut and encourages drinking. Yet the combination of higher body weight and increased heat of digestion of forage can be bad for heart rates, body temperature and recovery times.

Endurance riders are on to this, as most substitute beet pulp for part of the hay in the period close to heavy training or competition days. Beet pulp is easier to digest and more calorie-dense, so you can feed less of it. It’s also a good way to get the beneficial digestive effects of a high-fiber diet and a good intestinal reservoir of water. Moderate grain, in amounts tied to how hard the horse is being worked, also makes it possible to reduce the amount of hay that is needed. Remember, though, that every horse should get at least 1% of its body weight in hay each day to maintain good intestinal function.

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Ultrasound For Colitis
Colitis is an acute inflammation of the colon, caused either by immune mechanisms or infectious agents such as salmonella or Potomac horse fever. It should be treated with intensive intravenous fluids, antibiotics and other medications, but many horses end up in surgery instead, which is not indicated for colitis.

The main symptoms of colitis — severe pain and dramatic signs of dehydration and toxicity — develop rapidly and are also seen with several other intestinal problems. Because of the horse’s quick downhill slide following the onset of symptoms, surgery is often opted for despite the lack of a clear diagnosis. Now, however, diagnostic ultrasound may prevent stress from unnecessary surgery in these critically ill horses.

A study at the College of Veterinary Medicine of North Carolina State University found that ultrasound detects colitis of the right dorsal colon (a common site) by measuring the thickness of the colonic wall on ultrasound images obtained at specific interspaces between the ribs. Ultrasound was also useful in monitoring the response to therapy, with inflamed walls returning to more normal thickness with the appropriate drugs.

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Ulcers May Cause Cribbing
Many horsemen claim cribbing causes digestive upset. However, we’ve always believed the reverse is more likely true, and a study performed at the University of Bristol and published in the Veterinary Record suggests this may be the case.

A series of young horses were examined endoscopically shortly after they started cribbing. The researchers found that the number and severity of gastric ulcers were significantly higher in cribbing horses. Many of the horses had gastric-ulcer formations that would have started well before the onsent of the cribbing. In addition, treatment with antacids also notably decreased cribbing.

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Caution With Newer Antibiotics
Newer antibiotics can be lifesaving when a horse has a bacterial infection that isn’t sensitive to old standbys like penicillin. However, they’re not always the best first choice.

The quinolone-type antibiotics (drugs that end in -floxin, -floxacin) can have damaging effects on the chondrocytes, the cartilage-producing cells, according to an American Journal of Veterinary Research study.

Any potent drug comes with a price tag of potential side effects, so the risk-vs.-benefit profile should always be considered before treatment. When dealing with infections, the ideal is to obtain samples for culture and antibiotic sensitivity before starting treatment. Barring that, or while waiting for results, your veterinarian will work out a plan regarding which drugs to try first, for how long and what criteria will be used to decide if a change is necessary.

Starting simple means you still have options in the “heavy guns” category if needed, that you are less likely to cause antibiotic-resistant bacterial strains and you may save considerable expense.