AAEP 2002: Feeding the Geriatric Horse
With more and more horses reaching geriatric status (over 20 years of age), it’s important to understand how their nutritional needs might change. Diets should be adjusted if necessary to help old-timers live long and healthy lives. David Pugh, DVM, MS, Dipl. ACT, Dipl. ACVN (nutrition), professor at Auburn University, presented “Feeding the Geriatric Horse” during the Current Concepts in Equine Nutrition session on Dec. 5.
Pugh began by saying that an older horse should have a complete physical exam, dental exam, and complete blood count and serum biochemistry panel to detect any problems. If an older horse has a medical problem, this information might affect the choice of diet.
If everything is normal, Pugh recommended that an older horse be given palatable, dust-free feedstuffs to minimize the risk of allergies and lung disease. These feedstuffs should be easy to chew and swallow to minimize the risk of choke. If an older horse is pastured with younger or more aggressive horses at feeding time, Pugh said it is helpful to feed the older horse separately to insure that he gets to eat properly.
A healthy older horse should be fed enough energy for the amount of calories he is burning--crude protein at 12-16%--and high-quality fiber for normal gut function, according to Pugh. It is important to make sure that the older horse is receiving enough vitamin C and vitamin B-complex and minerals to maintain nutritional health. He said that vitamin C levels tend to be lower in geriatrics. One study showed that in older horses with depressed immune systems, giving 10 grams of vitamin C twice a day might increase antibody response. Vitamin C is water soluable and thus is hard to detect a toxicity, so Pugh recommends not going above this level. He also reminded horse owners that they should always consult their veterinarians prior to feeding any supplement.
Pugh said he likes senior feeds as they have increased amounts of crude protein, fat, phosphorus, and vitamins; are easy to chew; and are palatable. Hay and grain should be of good quality. One to two cups of vegetable oil per day can be added to some diets for additional fat. However, Pugh cautioned against adding fat too quickly; fat should be added over a two- to three-week period.
When providing a feed other than a complete feed or commercial mix, digestibility should be taken into account.
If feeding hay cubes, up to a half-gallon of water per pound of feed must be added to decrease the chance of choke and colic and to increase intake.
Problems with the Older Horse
An older horse might be affected by a multitude of age-related problems. These might include weight loss, parasite problems, dental disease, ill thrift, hepatic (liver) disease or compromise, renal (kidney) disease or compromise, pituitary adenomas, thyroid adenomas, colic, and Cushing’s disease.
An older horse should have a body condition score between four and six, according to Pugh. (For more on body condition scoring, see Quick Find Article #2861.) If the horse has a low body condition score, results of a physical exam are normal, and the horse does not have renal or hepatic disease, then Pugh recommended adding vegetable oil or rice bran in order to increase energy intake. However, when adding rice bran, the calcium-phosphorus ratio (Ca:P) must be corrected since rice bran is high in phosphorus and has an inappropriate Ca:P ratio.
For a body condition score of 1, an owner should not try to fatten a horse too quickly as this could cause problems. Expect it to take two to three months to improve the horse to a body condition score of two. Raising a horse from a body condition score of two to three can take another two to three months; an increase to a body condition score of four can take one to two additional months. Expect a similar timeframe to go from a body condition score of four to five.
If there is weight loss with no underlying disease, the horse should be fed a very palatable, easy-to-chew, easy-to-digest, dust-free diet that has a higher protein content (12-16%), maintenance levels of calcium under 1%, and phosphorus at 0.4-0.65% while maintaining a Ca:P ratio of 1.5-1, suggested Pugh. He said that soybean meal is an appropriate source of good-quality protein. He also recommended adding a yeast culture for improved nitrogen retention and using extruded feeds for increased digestibility.
However, if yeast is added to an older horse’s diet and he goes downhill or experiences diarrhea, then quit feeding it, he said. Again, any dietary change should be based on a well-thought-out plan based on recommendations of your veterinarian and a nutritionist.
In one study, pelleted/extruded feeds improved weight gain, body condition scores, and plasma total protein better than a commercial sweet feed. Vegetable oil can be added to help maintain weight.
Chronic weight loss can result from parasites, dental disease, infectious disease, non-infectious disease (such as cancer or hepatic disease), neglect or abuse, and inadequate feed.
“Chronic parasitism can potentially affect long-term digestive ability, therefore strict attention to parasite prevention is paramount for a long, healthy life,” said Pugh. If weight loss is noticed, the parasite prevention program should be examined to see if it is adequate.
Pugh listed sharp points, misaligned teeth, and broken, missing, misshapen, or long incisors as common dental problems found in older horses. He prefers that older horses have a bi-annual, or at least an annual, dental exam. Dental problems can cause problems with chewing or swallowing, but switching to a pelleted feed (if the feed is moistened to a thick soup consistency), or using a ground or extruded feed can help ingestion and digestion of feed. He also recommended chopped hay or hay cubes for bad teeth.
According to one study done at Auburn, out of 104 referred cases of colic in horses over 17 years old, grazing difficulty, lipomas, and dental disease were the major predisposing factors. Pugh cited another study that discussed predisposing factors for colic in older horses. Those factors included being stalled over half of the time, a recent change in housing, access to a water bucket (access to a pond decreased the chance of colic), and limited access to pasture. Feeding extruded feeds was shown to reduce the risk of colic.
Pugh recommended that if a horse is losing muscle, feeding a yeast culture and increasing
the crude protein in the total diet might help, providing that renal function is normal. In addition, a horse must be receiving adequate phosphorus (0.4-0.6%).
Renal and Hepatic Problems
Pugh cited a study that found an increase in renal calculi (calcifications, or “stones”) in aged mares and geldings fed alfalfa hay. For horses with renal disease, Pugh recommended avoiding beet pulp, legume hay, and high-protein diets. He recommended grass hay with a protein content of 8-10%, hay cubes, or pellets. Vegetable oil can be added if necessary to maintain weight, and supplemental B-vitamins (such as Brewers yeast) can also help digestion.
In the case of hepatic disease, Pugh told the audience to avoid high-fat, high-protein diets, and, again, adding Brewers yeast might be helpful. He recommended a relatively high-carbohydrate, low-fat diet. Some of his preferred feedstuffs for horses with hepatic disease include grass hay, moistened pellets, chopped hay, hay cubes, beet pulp, rolled corn, and barley.
In one study, researchers found 10 out of 13 horses had pituitary or thyroid adenomas (tumors). The presence of a tumor might affect mineral balances. Pugh said that if a pituitary adenoma is found with concurrent glucose intolerance, then sweet feeds should be avoided. Vegetable oil can help maintain body condition, but only after liver function is tested and found to be normal.
Pugh said that chronic pain should be relieved with non-steroidal anti-inflammatory drugs, chondroitin sulfate (for joint pain), and possibly alternative therapies such as acupuncture. If laminitis is the cause of chronic pain, starch intake should be decreased, and the horse should have both feed and fiber increased. In the case of chronic obstructive pulmonary disease (COPD), dusty hay should be avoided.
An audience member asked Pugh what he would recommend for a horse with Cushing’s disease. He said to avoid molasses and a high-carbohydrate diet. If the horse has normal hepatic function, then increasing fat and protein is recommended.
Pugh cited a study on the use of unprescribed supplements. In horses fed unprescribed supplements (what you can buy over the counter or through the mail), supplemented horses were twice as likely to be receiving excessive amounts (over 20% of the Nutrient Requirement Council’s recommendations) of all nutrients. This could potentially cause damage to the horse. In addition, those supplemented horses were 10 times more likely to be receiving excessive amounts of individual nutrients. Diets were unbalanced 78% of the time.
While Pugh said the mineralized salt blocks or free-choice salt are fine for all horses, as are recommended vitamin/mineral supplements for a specific purpose (i.e., if your veterinarian or nutrionist recommends biotin for certain hoof problems, vitamin C for stressed animals, or vitamin E to improve IgG in colostrums).
About the Author
Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.
POLL: University Equine Hospitals