There’s no shortage of senior horse feeds on the market, but does every horse eventually need one? And if so, when?

Articles from the 1980s and 90s stated that senior horses experienced reduced fiber fermentation with poor absorption of phosphorus and protein. Therefore, these horses needed higher calories, protein and phosphorus in their diets. Later studies confirmed this to be true – but it’s now thought the problem was caused by chronic parasite damage to the horses’ intestinal tracts, since modern effective paste de-wormers were not available during the lifetimes of most of these horses. In fact, subsequent studies have shown that the nutritional requirements of senior horses are actually identical to those of younger adults.

As a general rule of thumb, this means that as long as your senior horse is in good health, with adequate weight, a nice coat and hooves, no diarrhea or other gastrointestinal issues, there is no reason to change the way you feed him.  However, there are things that come into play with many seniors which may require you to make some changes.

The most common indicator that something has changed is weight loss, and an inability to hold a normal weight on the usual amount of food. If your horse develops this problem, it’s usually a good idea to have a veterinary evaluation done to rule out a serious underlying medical condition. For instance, older horses are at risk of developing Cushing’s disease. Weight loss and muscle wasting are common signs of this disorder. Older horses may also have a weakened resistance to intestinal parasites, even becoming susceptible to parasites that are normally only a problem for foals, such as Ascarids (roundworms). Much less common, but also possible, are things like liver or kidney disease and malignancy.

If the horse is free of any of the above causes of weight loss, attention then turns to management and digestion.

Management concerns

Group dynamics

If the horse is being maintained in a herd situation, the first step is to spend some time observing interactions in the group. As horses age, they may lose status and be prevented from eating their share by stronger, more aggressive horses. Even if there  seems to be enough food available for all, the older horse may have to make do with the less palatable and less nutritious  portions – e.g. more stemmy portions of hay — that remain after the others have picked out what they want.

Pain

Pain from chronic conditions like arthritis or old tendon/muscle injuries may also be a factor.  Pain itself can reduce appetite. It may also keep the horse from moving around to reach food or water. Inadequate drinking will reduce how much food the horse eats.

Temperature

Older horses may have more trouble regulating their body temperature – either cooling off in heat or keeping warm in winter, or both! If they sweat more in summer, they will have higher salt and water requirements. When keeping warm is the challenge, they need more calories.

Issues with eating and digestion

Dental issues

On the digestion end of things, the place to start is the mouth. Routine dental care can help with uneven wear and sharp points, which are issues a horse of any age may have. As he ages, the raised ridges on his molar surfaces wear down, impairing his ability to grind food. Teeth are narrower close to the root, and as this progresses, gaps called diastemas develop between the teeth at gum level. These can trap food and become inflamed. Cavities, cracks and loose teeth can also be an issue, as well as periodontal disease and root abscesses. Horses with Cushing’s are more susceptible to infections of the tongue or bone caused by unusual organisms from the oral cavity. Frequent regular exams are needed to keep on top of these issues.

Problems with ineffective chewing can occur even if the mouth looks to be in good condition. This is because the alignment of chewing surfaces changes with age. As a result, the force generated during chewing is reduced, leading to less efficient maceration of the food. Poor chewing reduces the efficiency of digestion and fermentation in the intestinal tract.

Choke

Choke is an impaction of material in the esophagus. It can happen at any age, but risk is increased in older horses. Choke can be caused by bolting food, which leads to larger particles and less saliva production. It may also be caused by age-related loss of the nerve control involved in swallowing.

Microbiome

Age has additionally been associated with changes in the intestines. The number and diversity of organisms in the microbiome is reduced. Why this happens is unknown, but the result is that the older horse is often less tolerant of diet changes and may not be able to eat fibrous hays without getting either obvious diarrhea or increased amounts of free fluid around manure balls. A very common history is that the horse does fine on pasture but loses weight and gets diarrhea when put on hay.

Innervation

Innervation (nerve supply) of the intestines is also reduced in older horses. This can predispose the horse to impaction (which is more common in older horses) and colic in general. Altered nerve supply may also be behind the aged horse’s increased risk of choke.

Routine feeding

An older horse’s nutritional requirements do not change, but his tolerance of deficiencies or excesses might. For example, a horse whose diet has always had periods of copper deficiency has been dealing with this over the years by drawing on tissue stores. As time goes on, those stores become deficient and he is now at risk of copper deficiency problems like tendon/ligament breakdown, anemia, or aneurysm and rupture of blood vessels – all common issues in older horses. Mineral supplementation should ideally be based on hay analysis or best estimate of regional dietary levels done by a professional.

Guidelines for mineral supplementation for the average-sized horse are as follows:

• Calcium — only as needed to meet requirements; excess increases risk of kidney and bladder stones and sludge
• Iron – avoid added iron
• Manganese – low
• Copper — minimum 150 mg
• Zinc — minimum 450 mg
• Selenium — as the region requires

All horses need a minimum of 1 ounce of salt daily — 2 to 3 ounces in hot weather and an extra ounce per hour when worked. If the horse is not on fresh grass, feed him 2,000 IU/day of vitamin E in oil and 4 ounces of flax or chia seed for Omega-3 fatty acids.

B vitamin supplementation is wise since the aging intestinal tract may not support normal numbers of microorganisms, which are a major source of B vitamins for horses.

Most equine diets contain adequate crude protein for seniors, but can be lacking in key essential amino acids. It is wise to supplement with L-lysine (10 grams), D,L-methionine (5 grams) and L-threonine (2 grams) daily.

Older horses with Cushing’s may develop insulin resistance and require a special diet low in sugar and starch to avoid laminitis. Most commercial feeds that claim to be “low” or “safe” are not low enough. For details, visit ecirhorse.org.

Troubleshooting tips

It’s possible a horse could live out his entire life without needing any changes to how he is fed.  Others will develop one or more of the issues mentioned above.  Being proactive will help you catch things early.

1. Carefully examine your senior at least once a month

Note general body condition and coat quality. Record weight from a weight tape as an objective measure you can use to track trends. Keep an eye on muscle bulk by palpating along the spine and measuring the circumference of the widest part of the forearm with a tape measure. There is very little fat in that area.

2. Monitor his intake and output

If you begin to see losses, check manure quality and look for undigested food in the manure. Watch the horse eat. Does he chew and swallow normally? Does food ever fall from his mouth? Does he finish his food in a normal length of time? If being fed in a group setting, is he able to effectively compete for food and water? Does he get enough salt?

3. Be wary of weight loss

A senior horse losing weight and/or muscle mass should be checked by your veterinarian, especially if the loss is sudden. If no underlying medical condition is found, the first thing to check is the hay, especially if the horse does fine on grass. The hay should be soft and leafy without tough stems. You can try soaking it to make it easier to chew and digest, but be aware that this will lower calories. An alternative is to provide at least half the daily calories from soaked grass hay pellets or cubes, or a soaked complete feed with high fiber (20% or higher).

Seniors have the same nutritional requirements as younger adult horses, but may run into issues that interfere with their ability to efficiently process and digest their food, or be kept from eating and drinking by younger herd mates. Senior horses are also less tolerant of deficiencies or excesses. If you monitor your horse’s weight and muscle carefully, and take advantage of the help available from your vet and nutrition experts, you can avoid any diet-related problems throughout his senior years.