Written by: Shannon Pratt-Phillips, Ph.D.

Shannon Pratt-Phillips, Ph.D., gives diet advice for geriatric or retired horses.

Thumbnail for Formulating a Feed Program for: A Senior or Retired Horse

Pam Mackenzie photo

Horses older than 20 are typically considered “senior” or “geriatric,” but even horses younger than this may have age-related changes that warrant some feeding modifications.

Because horses’ teeth are a finite length/size, and continue to erupt from their jaw and gumline throughout life, eventually there will come a time where there is little tooth left, and the teeth may fall out altogether. This clearly poses a challenge as to what a horse may eat, because it will affect the chewing and grinding ability, making the consumption of coarse feeds, such as long-stem hay, difficult. Regular dental checks from your veterinarian are increasingly important as your horse ages.

Older horses also tend to have changes in their social hierarchy, and may be lower in social rank than during their younger years. Therefore, it may be important to keep older horses together, and feed them their concentrates (and even forages or all feeds, depending on the situation) individually, to ensure they are actually getting what they should be.

Older horses are also more likely to have challenges such as disease (Cushing’s syndrome, cancer, arthritis) and may have weakened immune systems, making them more at risk of contracting some diseases. Again, frequent health checks and vaccination protocols from your vet are extremely important.

Many of these issues are managerial rather than nutritional, but can greatly affect how you feed your horse and what you feed him. Because of these issues, older horses may have problems maintaining their body weight and may lose muscle tone, also warranting more diligence to their feeding and frequent monitoring of body condition scores.

From a nutritional requirement standpoint, there are a few nutrients that appear to be more poorly digestible with age, and should, therefore, be fed in amounts slightly higher than maintenance, and come from highly digestible sources.

Protein and phosphorus are two nutrients that have been shown to have reduced digestibility in older horses, which can be compensated for by feeding in slightly elevated amounts, and from good quality sources. Fibre is also more poorly digested by horses, and while there isn’t a specific requirement in grams (or kg) per day for fibre, it is simply recommended that older horses be fed high-quality fibre sources – like leafy hay, pasture, beet pulp and rice bran. Older horses may also have lower vitamin C (ascorbic acid) status, potentially as a result of a decreased ability to synthesize vitamin C, or an increased need for this antioxidant with age. Horses, unlike humans, nonhuman primates, guinea pigs and fruit bats, can normally synthesize their own vitamin C, and therefore, do not have a nutritional requirement for it under normal conditions.

Other nutrient requirements may also be impacted under certain disease conditions – like a need for controlled salt or protein intake, if there is kidney or liver disease, but these should be addressed individually. There is emerging evidence supporting the effectiveness of some omega-3 fatty acids (namely DHA and EPA, found in fish oils) that may help with inflammatory processes such as arthritis in older horses.

In this example, we will use a 500kg “older” horse. While some older horses have lower metabolic rates as a result of reduced muscle tone, others, in fact, have a hard time maintaining weight and, therefore, energy (calorie) requirements may be elevated above maintenance simply to maintain body weight. As such, I will use the “average” level of metabolism, and allow owners to adjust calorie requirements as needed for their own horse. The protein and phosphorus intakes are elevated in this case to reflect the reduced digestibility, and calcium is increased slightly to ensure more calcium is fed than phosphorus. While vitamin C does not have a specific requirement (because it is not normally needed), it should be added to any diet formulated for an older horse.

High-quality hay (leafy, green, fresh smelling) is ideal for senior horses. However, if a horse has poor teeth, soaked hay cubes can replace the weight offered in long-stem hay, as they should be fairly similar in nutritional composition as long-stem hay, but are just chopped and processed. Note that unsoaked hay cube weight should be similar in amount by weight fed as fresh hay.

If extra calories are required to maintain body weight, a mixture of soaked beet pulp, rice bran and vegetable oil can add in some calories without altering the nutritional ratios too much. Note that oil can be fed up to two cups per day, which works out to be about 2.3mcal/cup – (you can add up to 4.6mcal just with oil); 1kg of beet pulp (out of the bag, no water added, no molasses) has 2.46mcal/kg; and 1kg of rice bran (out of the bag, no water added) has about 3mcal/kg. So, if a horse still needs 3mcal per day to meet their energy requirements (assuming all other nutrients are met), you could feed, for example, a half cup of oil per day (1.15mcal) and 0.75kg of beet pulp (1.845mcal).

As a side note, I am frequently asked about specific supplements to facilitate muscle building, particularly for older horses that have lost muscle tone and topline. Sadly, there is no magic supplement for muscle building. Exercise must be part of the regime to build muscle. If you’re concerned your horse’s muscle mass is decreasing with age, discuss your horse’s workout regime with an exercise physiologist and your veterinarian to accommodate any arthritis and lameness issues. Exercise, along with a high-quality diet (like those described here), will help your horse maintain its muscle tone more than any supplement alone.

It should also be pointed out that several of the supplements marketed for “senior” horses include many non-nutritional ingredients, such as devil’s claw and MSM or probiotics. While these may help arthritis-associated inflammation or digestibility, they are not all fully proven to be effective, and there may be issues with “testing positive” in competition, since some ingredients are not well-researched.

Ingredients such as omega-3 fatty acids and ascorbic acid (vitamin C) are commonly found in senior products, and may, in fact, be warranted.

Example Diet 1

– 7kg of good quality hay or hay cubes (10% protein, 2mcal/kg digestible energy)
– 1.2kg of dry weight unmolassed beet pulp, then soaked with water
– 50g of “senior” vitamin/mineral supplement with 4% calcium, 3% phosphorus and added vitamin C
– Free choice salt (average consumption about 50g per day)
– Vegetable oil as needed to maintain body weight (not shown in graph)

Example Diet 2

– 4.75kg of good quality hay or hay cubes (10% protein, 2mcal/kg digestible energy)
– 2.5kg of “senior” commercial feed, with 14% protein, 6% fat and 16% crude fibre (includes added vitamin C)
– Free choice salt (average consumption about 50g per day)
– Vegetable oil as needed to maintain body weight (not shown in graph)

Doctor’s Notes

In this year’s series, equine nutritionist, Shannon Pratt-Phillips, Ph.D., is providing some example diets for horses indifferent classes, but remember these are examples, as each horse is different.

In each example, an average 500kg mature body weight is used, all noted requirements are taken from the NRC’s 2007 Nutrient Requirements of Horses, and all forage and feed information is from www.equi-analytical.com and Pratt-Phillips’ own databases.

Obviously, a horse’s diet will differ depending on the quality of hay or feeds offered, and hay analyses are suggested to accurately evaluate your own horse’s diet. If commercial feeds or supplements are warranted in a diet program, Pratt-Phillips presents a fictional formula (and provides goal percentages for several nutrients), though these may or may not be very similar to commercially available brands. It is suggested that you look for similar feeds, and work with a qualified equine nutritionist to help you select a feed or supplement that compliments your hay to meet the nutrient needs of your horse.