It is estimated that there are over 700,000 senior horses living in the United States today. There was a “horse baby boom” in the mid-to-late 1970s, making 9-11% of the total horse population today older horses. Many of these horses are well into their 20s or 30s, and still live very healthy, active lives due to better care and feeding.

The best manner in which to care for older horses is to address their special needs prior to any significant decline in condition or health. As always, your veterinarian plays a key role in helping to ensure the continuing good health and longevity of your horse.

Three main areas of attention needed for the older horse are nutrition, management, and health.

Dental – Teeth that are worn or missing make chewing difficult for the horse. Poor dental care can also cause mouth ulcers resulting in pain. Poor teeth contribute to the horse not chewing its food long enough to produce the amount of saliva necessary for proper digestion. Saliva not only contains enzymes important for the digestion of feed, but it also helps to lubricate the esophagus for ease of swallowing. If a horse is dropping bits of feed or forage out of its mouth, chances are there is an underlying condition in the mouth. In addition, feeds that are processed and easy to chew will help the problem of dropping feed. Water can also be added to the feed to make a gruel which will be even more edible for the horse with poor dental condition. A horse can literally “drink” a meal if teeth are in extremely poor condition.

Digestive System – As the horse ages, the motility of the digestive tract becomes compromised. One reason may be due to the fact that the horse itself has become less active. However, digestive concerns still can occur in those individuals that remain active, even as an older horse. Gas production and impactions can lead to colic symptoms. By feeding smaller meals more frequently, the horse can more easily digest and process its feed. Reducing starch or grain in the diet can be helpful in preventing excess gas and constipation. Increasing the amount of a high quality, easily digestible fiber source may also assist in this regard. As always, offer plenty of clean, fresh water to keep food moving through the system. Consider adding 2 ounces of salt to the horse’s diet to stimulate water consumption. Remember, horses prefer tepid water from 45 to 75 degrees Fahrenheit.

As part of the aging process, the older horse experiences a reduction in digestive efficiency, along with a decline in its ability to absorb nutrients. By feeding a processed feed, as opposed to whole grains, and by fortifying the nutrient levels in that feed, the horse is better able to absorb those nutrients which are made available in its diet.
Parasite infestation also hinders digestive capabilities, so a proper deworming and parasite control program must always remain paramount in proper maintenance and care of the horse at any age.

Body Weight – Though some senior horses have a problem with being overweight, it is much more common to see older horses that have become too thin. Aging tends to result in a reduction of muscle mass, along with difficulty in maintaining adequate weight. As mentioned earlier, the older horse may not absorb nutrients as efficiently as it had been able to do in its younger years, or may be experiencing problems with chewing and digesting. Monitor horse’s body weight using the established Body Condition Scoring System, paying special attention to weight over the top line, back and rib cage areas.

If your horse is too thin, feed a processed feed that contains high quality, easily digested protein and readily available energy. If the horse is too fat, minimize grain intake to control calories, yet still assure that proper protein, along with correct vitamin and mineral balance, is being maintained.

Hair and Skin – An inadequate diet is often to blame for problems with hair, skin, and hooves in horses of all ages, but is especially evident in the older horse. Regular brushing and a good nutrition program will contribute greatly to resolving these conditions. Nutrients such as protein, essential fatty acids and vitamins are particularly important, and many times are inadequate in a typical diet. Poor hair coat in older horses can sometimes be due to Cushing’s disease. This is caused by a tumor in the pituitary gland. Symptoms of Cushing’s disease include long hair coats that shed late in the year or in patches, loss in muscle mass and excessive water intake. Consult your veterinarian if you feel your horse may be showing these symptoms.

In a study of geriatric horses, over 70% of the horses over 20 years of age showed subclinical signs of pituitary or thyroid dysfunction. These dysfunctions can cause an intolerance to glucose or blood sugar. After a meal high in starch, such as cereal grains, blood levels of glucose and insulin become abnormally high. Horses with Cushing’s disease respond to diets that are lower in starch and higher in fat and fiber. With proper veterinary care and nutritional management, these horses can live for years after the appearance of the clinical signs.

Bones and Joints – As horses become older, we begin to see lameness which may be due to chronic founder or laminitis, arthritis, or stiffness from weakened bones due to demineralization. The first course of action is to obtain veterinary assistance to aid in alleviating discomfort. Depending upon the specific condition, management recommendations may vary. Nutritionally speaking, it is important to provide a nutritionally balanced diet providing more calories from fat and fiber, as opposed to starch, along with a good mineral balance.

Anemia – Anemia is a reduction in red blood cells and can occur in horses of any age for a variety of reasons. In the older horse, anemia may be the result of poor nutrient utilization, or a decrease in red blood cell production. It can also be associated with heavy infestation of parasites. By providing a palatable, easily digested and balanced feed, the horse will receive and utilize the nutrients essential to its good health. In some situations, an extra blood-building nutrient may be recommended by the veterinarian.

In summary, our large population of older horses can continue to provide us with joy and entertainment for many, many years provided that we, as their caretakers, are aware of their changing needs and make certain that we do whatever we can to provide them with the best care possible in their golden years. Through proper nutrition, management and health care, we can help our older horses to continue to thrive for many years!

By Tina M. Anderson, PhD

AAFCO defines a number of yeast products as feed ingredients, including dried yeast, yeast culture and yeast extract. Dried yeast may be either active or nonfermentative. Yeast culture is a dried product composed of viable yeast cells and the media on which it was grown. Yeast extract is a dried or concentrated product of cell contents from ruptured yeast cells.

Studies in ruminants suggest that addition of yeast products to ruminant diets promote bacterial growth in the rumen. It is generally believed that yeast additives either directly facilitate fiber digestion and dry matter intake, or contain metabolites or compounds that stimulate bacterial growth to facilitate fermentation and animal performance in ruminants. Since horses have fermentative capability in the hindgut, it has long been proposed that yeast products may have beneficial effects on digestion/fermentation in the hindgut, resulting in enhanced fermentation and increased fiber and/or nutrient digestibility.

According to the 2007 National Research Council’s Nutrient Requirements of Horses, “Unlike observed effects in ruminant studies, supplementation of yeast in horse diets tended to show some beneficial effects on fermentation, but results were equivocal across studies.” There is great variation in published results of feeding yeast products to horses – most studies report minimal to no increase in cecal or colonic bacterial cultures as a result of feeding yeast products, although a few studies have reported beneficial effects when yeast products were fed with very high starch diets, or with low quality forages. Some studies have reported no improvement in nutrient apparent digestibility when yeast products were fed to mature horses, but others have reported some improvements in fiber and nutrient digestibility. However, the reports of improved digestibility of nutrients with the addition of yeast products are most often seen when yeast products are added to nutritionally deficient diets. The Purina Equine Research team recently completed a thorough, long-term study that looked at the efficacy of yeast in enhancing fiber digestion in horses, as well as several other parameters, and the data indicated no effects of yeast on fiber digestion. This data is currently being prepared for submission for publication in a scientific journal. However, ongoing Purina research continues to investigate potential effects of yeast products on other parameters of equine digestion, health and performance.

Yeast products can be a source of quality nutrients, including essential amino acids and B-vitamins, so adding yeast products to a nutritionally deficient diet will result in improved performance in horses, just as addition of any ingredient that supplies deficient nutrients to a ration will result in improvement in performance. However, when yeast products are added to diets that are nutritionally balanced and fortified to meet a horse’s nutrient requirements, the additional nutrients provided by the yeast products have not shown measurable benefit. At this time, there is insufficient data to support the inclusion of yeast products in horse feeds for benefits other than those simply provided by the nutrient content of the yeast products, and there are many other feed ingredients that provide quality nutrients for optimal nutrient content in horse rations. Purina Premium Horse Feeds are nutritionally fortified and balanced with quality protein sources as well as specific essential amino acids, minerals and vitamins to meet horses’ nutritional requirements when fed as recommended. And, of course, if and when we elucidate beneficial effects of yeast products in horses, we will share those findings with our customers and add them to our feed formulations.

Katie Young, Ph.D. Land O’Lakes Purina Feed

Water and electrolytes are excreted from the body primarily through sweat, urine and fecal output. The body attempts to maintain a balance between dietary intake of electrolytes and excretion rates. Kidneys adjust the volume and concentration of urine based on the water and electrolyte balance in the body through an intricate hormone signaling system. Electrolytes are not stored in the body, so the amount needed daily must be provided in the diet. If dietary electrolyte level is lower than needed, the kidneys will conserve and reabsorb electrolytes. If dietary electrolyte supply is more than needed, the kidneys will flush any excess. This very complex mechanism keeps water and electrolyte balance tightly regulated under normal circumstances. However, when the relationship between intake and output is challenged, normal mechanisms may not maintain the balance.

Hard work, especially in hot and humid conditions will challenge normal water and electrolyte balance mechanisms. Under these conditions, horses can lose as much as four gallons of sweat per hour, which carries with it approximately 10 tablespoons of electrolytes – primarily sodium, chloride and potassium. Human sweat is hypotonic, meaning the concentration of electrolytes in the sweat is lower than the concentration in the blood. As people sweat, sodium concentration in the blood rises. This triggers the thirst response causing the person to want something to drink. Horse sweat is hypertonic, the concentration of electrolytes in the sweat is higher than the concentration in the blood. As the horse sweats, sodium concentration in the blood remains unchanged even though large amounts of sodium are being lost in the sweat. Without the rise in blood concentration of sodium, the thirst response doesn’t kick in. This is why dehydrated horses often show no interest in drinking, which simply makes the situation worse.

Hay and pasture contain high levels of potassium and a normal diet will provide adequate potassium to meet requirements of most horses. Usually, only hard working horses that sweat for prolonged periods need additional potassium supplementation. Most commercial horse feeds contain 0.5 – 1.0% added salt (sodium chloride) which, along with free-choice access to a salt block, will supply adequate sodium and chloride to meet requirements of horses in light activity. Horses being ridden regularly and sweating moderately on a daily basis cannot eat enough salt from a salt block to meet their needs. Providing 2 – 4 tablespoons of loose salt daily in the feed will meet the increased requirements. For horses that are sweating profusely, a mixture of 2/3 sodium chloride and 1/3 potassium chloride (Lite salt), would provide adequate sodium, chloride and potassium to replenish the higher losses. Commercial electrolyte supplements are also available, but should contain sodium chloride as the primary ingredient.

Providing daily electrolyte supplementation beyond what a horse needs to maintain balance can be very counterproductive. The kidneys will become very efficient at flushing the excess electrolytes out of the system and then on a day the horse really needs a higher level, they won’t be available. The current recommendation for electrolyte supplementation is to provide additional electrolytes the day before, the day of and the day after a horse is going to work very hard and sweat a great deal. It is also very important that electrolytes are only given to well hydrated horses. Since you can lead a horse to water but you can’t make him drink, dehydrated horses should receive fluids intravenously to be sure water balance is adequately restored.

By Karen E. Davison, Ph.D., Manager – Technical Services, Purina Mills, LLC