I have a seven-year-old Thoroughbred gelding that weighs 1,100 lb (500 kg). He has been off work for about eight weeks, as he came down with strangles. His two pasturemates had not traveled for weeks either. The vet did not culture but diagnosed on symptoms (mild). Penicillin was given for five days, and during that time he had mild appetite depression. He is now recovered and seems anxious to get back to work. He has terrible anxiety over trailering, and we’ve worked on loading for months, starting with very short trips and returning home. We had to stop this part of his schooling because of his illness. In the meantime, I have heard discussion about vitamin B deficiencies in Thoroughbreds. He came from a money-strapped small operation where feed was oats mixed with sweet feed. He has been with us for almost a year, yet drought conditions in Texas have made pasture less nutritious. I feed him a low-starch feed and several supplements: rice bran, ground flaxseed, joint supplement, minerals and vitamins, and biotin. Do you recommend trying thiamin and tryptophan? He has also been on aloe vera juice to help any ulcers. He generally is a very good eater. Ample grass hay is part of his diet also. I am trying to find a way to reduce his stress for trailering and general calming as we go about our schooling here on the property.
B-vitamin deficiencies are not that common in healthy horses that have adequate forage in their diets, and your horse seems to consume sufficient forage. The microbial population responsible for digestion of the fiber in the forage also produces B vitamins. Where nutritionists sometimes see deficiencies is when a horse is not eating well, has inadequate forage in the diet, or when the digestive tract has been damaged. Having mentioned that, sometimes horses that are very nervous respond to supplementation of certain B vitamins, like thiamin, when given in therapeutic amounts (well above the requirement).
For example, an 1,100-lb (500-kg) horse has a requirement of 30 mg thiamin per day, but a leading calming supplement supplies 1,000 mg thiamin per dose. The use of B vitamins in therapeutic amounts is not uncommon, as this is usual with hoof supplements that include biotin. There is no established requirement for biotin because there has never been a report of biotin deficiency; however, research has shown an improvement in hoof integrity with supplementation of 20 mg of biotin a day.
Another nutrient thought to have calming properties for nervous horses is magnesium. Although most of the evidence is anecdotal, many Thoroughbred owners swear by magnesium supplementation at around 5 g per day. Magnesium is another nutrient that is rarely deficient in the diets of normal horses but when given in therapeutic amounts may help the horse.
Another product to give thought to would be something that supports the digestive tract. With the stressors that this horse has been through lately, perhaps the aloe vera is not enough to deal with any possible ulcers that might have developed. When a horse has ulcers or hindgut acidosis, it can affect its ability to concentrate or relax. If you observe any of the other signs listed in this information sheet, you may want to consider trying RiteTrac. This product has antacids and stomach soothers as well as a hindgut buffer for problems throughout the digestive tract.