Nutrition is important at all stages of life, but as horses age, they can have special dietary needs that help them thrive during their golden years.

Horses are living well into their 20s and even into their 30s, redefining what a senior horse is, says Kerry Kuhle, an associate professor in the Department of Veterinary Population Medicine (VPM) at the College of Veterinary Medicine (CVM). About 11 percent of horses in the United States are over age 20, and one-quarter of those are 30 or older.

“Horses are living older and living well—30 is the new 20,” Kuhle says, adding that a horse’s geriatric years typically start around age 20.

The basics of the senior equine diet

A tailored diet that follows some general rules of thumb is important to help treat chronic diseases that are common among older horses, such as dental disease and endocrine disorders, as well as the normal impacts of aging, including muscle loss, weight loss.

“These are important, and they can all play on each other; for example, we can have weight loss secondary to dental disease,” Kuhle says.

Forage

Forage is the base of the equine diet, and should make up the majority of the diet. Forage provides essential nutrients, energy, and fiber that help keep a horse’s digestive tract in good health. Sources of forage include:

• Pasture
• Hay
• Processed forage products (hay cubes, hay pellets)

Up to 50 percent of forage can be replaced with a forage substitute, such as beet pulp, which is a great source of prebiotic fiber, but stresses that it should make up no more than half of a horse’s total forage for the day.

Ration balancers

Balancers can be added to a horse’s diet to provide trace minerals, vitamins, and protein. Balancers come in concentrated formulas that are generally moderate in starch and sugar and low in calories.

“Balancers are one of the greatest inventions we’ve had in equine nutrition in the last few decades,” Kuhle says. “When I think about a diet for an adult horse, the first thing I’m going to add is forage. Then I need to fill in the gaps, and the first thing I think of when filling the gaps is ration balancers.”

A good rule of thumb to determine if a bag at the feed store is a balancer is to look at the feeding rates, Kuhle says. Feeding rates for balancers are very low, generally 1–2 pounds per day.

Supplemental feed

Sometimes horses need more calories than balancers can provide. In those cases, Kuhle reaches for supplemental feed.

Sometimes called concentrates or grain, supplemental feed comes in formulations specifically for different horses at different stages of life or different health targets, such as joint or digestive health. These are fed in higher amounts than balancers, usually 2–6 pounds per day, and contain more calories than balancers.

“Read the bag to see who your target audience is,” Kuhle says, adding that, ultimately, which supplemental feed is best for your horse depends on the individual horse and what else they are eating.

Complete feeds

Complete feeds are full of fiber and high-quality nutrients that a horse’s digestive system can break down easily. They typically come as pellets and can be soaked in water and easily gummed down by horses that have dental disease or weak teeth.

“They can be used with forage, as a supplemental feed, or on their own,” Kuhle says.

Again, she recommends reading the feeding instructions on the bag. Many senior feeds are complete feeds, but not all of them, so don't assume that because a feed is labeled "senior", it's automatically complete.

“If it has instructions for feeding with or without hay, it is a complete feed, " she says.

Fats

In some cases, a horse needs more calories, and that is where fats can help. If a horse is sensitive to grains, a feeding regimen can include fats in place of more carbohydrate-dense feeds.

Fats come in many kinds, including:

• Vegetable oil
• Flax (ground and oil)
• Stabilized rice bran (ground and oil)
• Extruded pellets (beware of starch and sugar levels)

“If your horse doesn’t eat a lot in one sitting, fat packs a big punch with a small amount of volume, and you can add them without worrying that you are imbalancing something else in your horse’s diet,” Kuhle says.

She also recommends adding an antioxidant such as 1–1.5 IU of vitamin E oil per milliliter of fat, and slowly introducing fat to a horse’s diet. Start with about ¼ cup of oil per meal and slowly increase to one to two cups maximum per day over the span of two or three weeks.

“They aren’t always palatable, and can cause digestive upset and diarrhea, so start with a small amount and work your way up,” Kuhle says.

Supplements

Just as is the case for people, there is no uniform definition of what a supplement is for horses. Supplements go beyond meeting a basic nutrition requirement, but cannot legally claim to be a treatment for any condition. Kuhle warns that supplements are poorly regulated in the U.S. and that you should try to get your horse everything they need through their diet.

“My general stance is that they generally don’t hurt, but they may not help,” she says.

If you do choose to introduce a supplement into your horse’s diet, Kuhle says it’s important to have a clear health goal.

“People often introduce supplements, and they don’t know if they are helping or not, but they are afraid to take them away in case they’re helping, and they don’t realize it,” she says. "If you go down that supplement road, try to have a goal identified, and then think about how you will measure if you are succeeding."

The basics

In addition to a carefully balanced diet, Kuhle says to always remember to feed horses clean water and give them free access to a salt lick.

“A white salt block is really all you need,” she says.

When to remove all long-stemmed fiber

If a veterinarian determines that your horse no longer has grinding capacity and is at high risk for choking or colic, it is time to remove all long-stemmed fiber from their diet. A telltale sign is bits of hay or whole oats appearing in their manure.

To start, that horse has to be separated during feeding time, though pasture is usually just fine, Kuhle says. Hay has to be replaced, pound for pound, by hay pellets or a complete feed, or a combination of the two, which can be more interesting for the horse.

“We are generally making these transitions slowly. The transition is really tough for the horse if you do it abruptly, so we’ll slowly transition over about 14 days,” Kuhle says.

How much food does your horse need?

How much your horse needs to be eating will generally be based on the horse’s weight and body condition. The horse’s body condition score will tell you if the horse is overweight or underweight.

Testing for vitamin deficiencies

Especially for horses that are not on pasture, Kuhle says it’s important to get a serum test done to determine whether the horse is deficient in vitamins that aren’t as available in hay, such as vitamin A and E. Other screening lab work, such as a complete blood test and chemistry, is also important.

Keeping up on dental visits and vaccinations also maintains a horse's health throughout old age. Kuhle says it’s important to vaccinate and provide parasite control even in very old horses that have been vaccinated throughout their whole lives.

Always weigh food

Feeding by volume is not an accurate way to feed, and under-/over-feeding is extremely common, Kuhle says. Store-bought concentrates, even those from the same brand, have different densities.

The good news is, you don’t have to weigh food every time you feed. Kuhle recommends getting a kitchen or luggage scale and weighing out the amount of feed you need to give your horse at each meal.

“You can weigh it the first time, mark on your vessel where that 1- or 2-pound line is, and then fill it to that line every time after that,” she says. Similarly, you can get an average weight for a flake of your hay and then feed by the flake. “I cannot press upon you enough to have a starting place. The first thing we want to do is weigh the current feeds, then we know what the baseline is. If we have a horse that is over or underweight, that might answer some questions.”

Listen to Kuhle’s full presentation on senior equine nutrition, and contact a nutrition advisor with any questions you have about your horse’s diet.