No doubt you've crossed paths with men and women in their 70s and 80s who are healthy, energetic, and active. I know of an 87-year-old woman who lifts weights at the gym twice weekly and volunteers each Wednesday to help familiarize new, fellow residents moving into the senior housing complex. By the same token, I know folks in their 50s and 60s whose medical problems are keeping them in the slow lane. Maybe it's true that "being old" is a state of mind, but for sure, it's also a state of how well the old body and bones hold up, too.
It's no different for horses. Some show signs of arthritis and unthriftiness before they're 18, while others are fit and frisky into their 20s. I remember when the great Canadian showjumping legend Big Ben retired at age 18 and the same year, the first Big Ben Challenge was won by For The Moment at age 20!
Clearly, horses age differently, so when it comes to reconsidering the dietary program of the senior horse, it's not a question of age, but of health. The senior horse which continues to do well on a diet should be maintained on that diet. However, once the older equine begins showing signs of aging--primarily weight loss and dental disorders--it's time to start making changes in his feeding program to assure the horse receives the nutrition he requires.
Changes With Age
Horses generally are considered old at 18-20 years of age, comparable to a 60-65 year old in human terms. Notes Ray Geor, BVSc, MVSc, PhD, Dipl. ACVIM, of R and J Veterinary Consultants in Guelph, Ontario, and nutritional consultant to Purina Mills, "The speed of physiological aging varies markedly between horses, perhaps the result of genetics and environmental factors (the latter might include the effects of lifetime diet)."
An old horse which has received a lifetime of good veterinary care and hasn't suffered parasite damage to his intestinal tract is not necessarily going to have changed nutritional requirements, says Joe D. Pagan, PhD, president of Kentucky Equine Research in Versailles, Ky. "However, if the old horse had not been well taken care of and had cumulative damage to the intestinal tract, then we're talking a different story." That's because years of dealing with internal parasites such as bots and strongyles on a daily basis can leave scars, reduce digestion sites, and damage the circulatory system. That can interfere with digestion and absorption, says Ginger Rich, PhD, of Rich Equine Nutritional Consulting, an independent equine nutritional consulting firm in Eads, Tenn.
Additionally, as some organs and body systems age, they often become less effective at utilizing nutrition. All of this can lead to weight loss.
"Typically, these horses lose weight over the topline," Pagan explains. "Their backbone becomes more prominent, their hind end becomes less prominent, and they tend to carry their body weight much lower. The horse seems to sort of sag."
Recognized changes in function that might have nutritional implications include:
Poor dentition--At some point, most old horses end up with dental problems; if they live long enough, their teeth actually run out as they continually erupt through the gums until they are gone. "Loss of teeth and abnormal wear patterns that result in malocclusion (poor bite alignment, e.g., wave mouth) can greatly decrease the ability to grasp and grind feed," says Geor. "Even if there has been no loss of teeth or obvious malocclusions, severe dental wear can decrease the ability to grind grains and forages. The result is a decrease in diet digestibility and poorer delivery of nutrients to the body."
Adds Gary D. Potter, PhD, PAS (Professional Animal Scientist), Dipl. ACAN, professor and leader of equine sciences at Texas A&M University, "Because very old horses with bad teeth can't make effective use of forages--especially low-quality forages--the normal function of the large intestine is compromised, including B vitamin synthesis and absorption."
Dental abnormalities also can predispose the horse to other gastrointestinal problems such as choke or large intestinal impactions because of poor chewing (mastication) of feed.
Besides weight loss, clinical signs of dental problems include unusually slow eating; turning the head sideways, slobbering, or dropping food when chewing; and poor feed consumption, says Potter. Owners might find quids (wads of partially chewed feed) on the ground or undigested grain in the manure.
Decreased saliva production--"When saliva is reduced, feed is not as well lubricated," explains Rich. "When the horse swallows, it may choke. Saliva is also a buffering agent that aids in the digestion process. Saliva production is controlled by the muscles used in the chewing process: The more a horse chews, the more saliva is produced. If chewing is impaired by poor dentition or because the feed does not require strenuous chewing (such as pellets), the amount of saliva will be reduced."
Decreased immune competence--"In several species, including horses, there is some evidence of a decrease in immune competence with aging," Geor says. "Whether nutrition can counter this decline in immune competence is not known. However, it is known that some trace minerals (e.g., selenium and zinc) and vitamins (e.g., vitamins E and C) play an important role in immune function, and diets for older horses should provide adequate quantities of these nutrients. One study demonstrated low plasma vitamin C in old horses."
Compromised intestinal, kidney, and liver function--Reduced organ function can lead to decreased fiber and phosphorus digestibility and reduced synthesis of vitamins and minerals.
Development of lipomas--"Colic associated with pedunculated lipomas (fatty tumors on stalks) in the small intestine are more common in old horses," says Geor.
Development of equine Cushing's disease, heaves, and chronic laminitis--"These disorders are more prevalent in the older horse," Geor reports, "and can dictate major changes in feeding management."
Food for the Aged
Once a horse has started showing weight loss or other "old age" signs, your veterinarian will likely suggest a more senior-friendly diet. He or she will want to do a thorough work-up to make sure the horse's kidneys and liver are in good shape before changing the diet. Although nutritional programs vary according to each horse's individual needs, circumstances, and maladies, Potter lists these basic nutritional principles:
- Forage must be highly digestible;
- Concentrates should be processed to facilitate digestion;
- Concentrates should be well-balanced; and
- Concentrates should contain B vitamins and other nutrients.
Generally, the senior diet should include slightly increased amounts of crude protein, energy, vitamins, and minerals. Rich recommends crude protein of about 12-14% of the total senior diet; Geor places that figure somewhat higher, at 14-15%, especially for horses in thin body condition and/or poor muscle mass.
"A good source of crude protein," says Rich, "is soybean meal."
Beware of feeding too much alfalfa hay, as the high calcium levels can be hard on an old horse's kidneys.
Fat is a good source of energy at less than 10% of the total ration a day, especially if liver function is reduced, notes Sarah Ralston, VMD, PhD, Dipl. ACVN, associate professor in the Department of Animal Science at Cook College at Rutgers University. Starchy grains and sweet feeds with lots of molasses should be used in limited amounts as energy sources since older horses might be glucose intolerant/insulin resistant. This can cause an increased risk of laminitis, adds Ralston. Passing the undigested starch into the hindgut can result in excess gas, diarrhea, colic, or founder.
Include 0.35-0.45% of phosphorus in the total diet. Older horses which have had parasite damage to their GI tract do not absorb phosphorus as well as younger counterparts; good sources are dicalcium phosphate or monosodium phosphate.
Rich recommends providing about 1,000 IUs of vitamin E each day to help improve the immune system. Conclusive research to support the addition of vitamins B and C to the senior diet is hard to find; however, Rich recommends providing elevated levels consistent with National Research Council (NRC) recommendations for a younger horse.
Rich suggests following the NRC daily requirements for long yearlings when feeding older horses. "This gives you a guideline of the increased amounts the senior horse needs," she says. NRC recommendations are found in books covering equine nutrition, available from equine programs at land grant universities, from your equine nutritionist, through your veterinarian, or online at www.nap.edu/books/0309039894/html.
Many feel complete and properly balanced senior feeds are a good option. "Clinical experience has indicated that old horses do best when fed a diet that delivers the highest quality nutrients in a highly digestible form," Geor emphasizes. "I generally favor the complete feeds that have been designed with this in mind--high-quality, easily digestible fibers, some 'precooked' or extruded ingredients that increase starch digestibility (and overall feed digestibility) and reduce the risk for delivery of undigested starch to the hindgut (which can result in colic or laminitis). In particular, these rations are an important part of the management of old horses with poor teeth."
Pagan agrees. "Senior feeds have been formulated to meet the requirements of the senior horse, so an owner is far better off to use one from a reputable company rather than trying to figure the right balance of nutrients on their own."
Nevertheless, owners might still be advised to supplement with additional vitamin C, vitamin E, and B complex vitamins. "Those vitamins are important for all horses, but may be even more important for these older horses," says Pagan.
When using senior mixes, be sure to feed recommended amounts. "Feeding only one to two pounds of these feeds will result in inadequate intake of many nutrients," Geor warns, "particularly if fed with poor to moderate quality forage." Provide a higher quality of leafy hay that is more digestible, less coarse, and less stemmy, says Pagan.
Ralston adds that if a senior horse needs 10-12 pounds of a mixed feed per day, no more than four pounds should be fed at one time. The product also should have greater than 15% fiber.
Horses with chewing difficulties need feeds that are more processed and thus easier to chew; the degree of processing is dictated by the severity of the dental problems. "The first diet change is to implement processed grains (crimped, cracked, rolled, extruded), then processed forages (cubes, pellets, wafers, chopped hay, haylage)," says Rich. "Alternative fiber sources such as beet pulp or soy hulls can replace all or part of traditional fiber sources like pasture or long-stemmed hay. If the horse is unable to chew or doesn't have enough saliva production to wash feeds down, then make a gruel of these mixtures by adding water."
Increasing the frequency of feeding with smaller meals can also help digestibility. "Any horse has a finite ability to digest starch in its small intestine," Pagan states. "That can be further compromised by food that's not chewed very well. Decreasing the meal size avoids overwhelming the small intestine."
Adds Rich, "Smaller meals that do not crowd the stomach and do not push feed through the digestive tract faster will aid these horses quite a bit. I recommend feeding some of these horses three or four times a day rather than once or twice a day."
Other Notes on Feeding
Obviously, it's important that the senior horse, especially one which has trouble maintaining weight, receive his full ration. But a once-dominant horse in a herd situation might find himself pushed down to the bottom of the pecking order as he ages.
"Make sure the horse has the opportunity to eat adequate quantities of the things he needs." Pagan recommends. "You may need to feed the horse separately."
Sufficient and palatable water supplies remain important, too. "A horse that is aging normally doesn't have much increased need of water, perhaps only an extra half-gallon a day," says Rich. "However, if your horse had been eating grass pasture then, due to lost or damaged teeth, is no longer able to eat pasture and is switched to an all-hay diet, cubed or pelleted feed, or to a feed with beet pulp shreds, his water requirement will increase. That's because pasture has 70-80% water in it whereas hay, pellets, cubes, and beet pulp shreds contain only 10-12% moisture, so the horse isn't getting as much moisture in the feed he eats. In this situation, water consumption out of the water bucket is going to increase."
In addition, horses with Cushing's disease will have dramatically increased water consumption.
Rich points out that in the winter months, many horses drink less water since cold water chills them (particularly those which have lost weight and thus have reduced body fat insulation) or problem teeth. "Providing warmed water, somewhere around 40-45°F (4.4-7.2°C), can increase water consumption and could minimize the risk of impaction colic."
Overall, the senior horse, particularly one which is showing signs of aging, is best served by regular veterinary evaluations at least once (preferably twice) a year including an evaluation of body condition, an oral exam, and an assessment of his nutritional program. While you can't prevent your horse from aging, making sure that your horse's diet provides him with the type of nutrition he needs could make the difference between a slow senior and an on-the-go senior.
McDonnell, S. Water Temperature and Drinking Behavior. The Horse, Feb. 2001, 31-32, article #66 at www.TheHorse.com.
See the Older Horse Care category under Basic Health Care at www.TheHorse.com.
See the Feeding Old Horses category under Nutrition/Supplements online.
About the Author
Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.
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