Slowing the Hands of Time: Nutrition and Management of the Ageing Horse

As horses live longer and remain active later in life, ageing horses now make up a significant proportion of the equine population. Many continue to be ridden, compete, and maintain a good quality of life well into their twenties and beyond. Understanding how ageing affects muscle mass, immunity, metabolism, and insulin sensitivity, and how targeted nutrition and management can support these systems, is essential for maintaining health, performance, and comfort in older horses. While ageing is inevitable, evidence‑based nutritional strategies can help slow age‑related decline and support healthy ageing.

When Is a Horse “Old”?

As with humans, there is no fixed age at which a horse becomes old. Many horses continue to be ridden, compete, and even reproduce well into their twenties. In disciplines that require years of physical development and training, such as dressage and showjumping, peak performance often occurs in the mid to late teens, with many horses not reaching their prime until 12–14 years of age.

From around 15 years of age, however, subtle but important changes begin to occur. The reserve capacity of many organ systems narrows, and the margin for error in common management practices becomes smaller. At this stage, nutrition can play a key role in smoothing the ageing process and helping to slow the hands of time.

Table 1. Horse Age compared to Human Age

What Is Ageing?

Ageing can be defined as “an irreversible, progressive, and time‑dependent decline in overall body function, resulting from the interaction of genetic and random factors.”

These changes are seen as:

• Alterations in body composition

• Loss of muscle mass

• Reduced aerobic and anaerobic capacity

Less visible, but equally important, are:

• Decline in immune function (immunosenescence)

• Chronic low‑grade inflammation (inflamm‑aging)

• Reduced ability to cope with heat and cold (thermoregulation)

• Increasing insulin resistance (reduced ability to load glucose into muscles)

Key aspects of healthy ageing that can be influenced by nutrition include:

• Muscle mass

• Immunity

• Insulin sensitivity

• Body weight and condition

Muscle Loss, Protein, and Amino Acids

With advancing age, speed, strength, and endurance decline, largely due to a reduction in muscle mass, which is often replaced by fat. This age‑related muscle loss (sarcopaenia) occurs in all species and is thought to be related to a reduced ability to synthesise protein.

The good news is that this age‑related decline can be offset by the essential amino acid leucine, which is naturally high in lucerne. The body’s ability to produce new cells, whether blood, muscle, or bone, depends not only on how much protein is fed, but on the amino acid profile of that protein.

Protein Quantity vs. Protein Quality

Most prepared feeds for adult horses contain 10–14% crude protein, but horses do not require a percentage of protein, they require a specific number of grams per day.

For example:

• 3 kg of a 10% protein feed = 300 g protein

• 1.5 kg of a 20% protein feed = 300 g protein

However, whether that protein is usable depends entirely on its amino acid profile.

The “Limiting Amino Acid” Concept

Proteins are made up of chains of amino acids, and good‑quality protein is rich in essential amino acids. Of the 22 amino acids found in nature, 10 are essential, they cannot be synthesised by the body and must be supplied by the diet.

Every feed ingredient (see Table 2) and every tissue in the body has its own specific amino acid profile or “recipe.” A useful way to think about this is baking a chocolate cake: it doesn’t matter how much flour, sugar, or eggs you have, once you run out of chocolate, cake production stops. In the same way, a deficiency in any single essential amino acid will limit new cell production, regardless of how much total protein is fed. Any excess or unusable amino acids are converted to fat. This is why crude protein percentage alone is a poor indicator of how much usable protein a horse is actually receiving.

When horses build muscle, they need certain amino acids from their diet. Lysine and threonine are the ones most likely to run out first, so they often limit how much muscle a horse can build or maintain. Even if a feed contains plenty of protein, muscle repair will slow down if these two amino acids are in short supply.

Leucine works a little differently. It acts like a signal that tells the body it’s time to build and repair muscle. However, leucine can only do its job if lysine and threonine are also available. In simple terms, leucine switches muscle building on, while lysine and threonine provide the material to actually build the muscle.

For muscle maintenance and recovery, especially in older or working horses, all three need to be present in the diet in adequate amounts.

Table 2. Amino Acid Levels in Feedstuffs (grams/kg)

Feeding Strategies to Support Muscle

• Feeding lucerne or a protein supplement within 2 hours before exercise ensures amino acids are available when muscles need them

• A small lucerne/protein meal before work also helps protect against gastric ulcers, which are more common when horses are worked on an empty stomach

• Feeding a small grain/protein meal within one hour after exercise, and hourly for the next 4–6 hours, supports muscle repair, rebuilding, and refuelling

Immune Function and Antioxidants

Ageing is associated with a decline in immune competence, increasing susceptibility to infections, cancer, and autoimmune disease. White blood cell numbers and their responses (killing capacity) decline, while inflammatory compounds increase.

Nutrients Shown to Support Immunity

In aged horses:

• Vitamin C (25 g/day as ascorbyl palmitate)

• Vitamin E (160 IU/kg of diet)

have been shown to improve white blood cell killing capacity and enhance the immune response to vaccination. This daily dose of vitamin C has also been shown to reduce the incidence and severity of “shipping fever”, a respiratory condition commonly associated with travel.

Inflamm‑Aging and Oxidative Stress

Chronic inflammation in ageing horses is thought to result from cumulative oxidative damage. While the body has its own antioxidant defence systems, the ability to synthesise antioxidants declines with age.

Suggested nutritional support for older horses in work includes:

• Alpha‑lipoic acid (2–4 g/day)

• Biotin (10–20 mg/day)

• Acetyl‑L‑carnitine (10–20 g/day)

• Coenzyme Q10 (400–600 mg/day)

• Increased intakes of selenium, vitamin A, and vitamin E

Recent studies have also shown that resveratrol (2 g/day) can reduce inflammatory markers and improve immune function in aged horses after just four weeks of supplementation.

Insulin Resistance and Feed Selection

Advancing age increases the risk of insulin resistance (IR), making low starch, low sugar, low NSC diets essential.

Many commercial feeds, including “senior” feeds, contain grains or grain by‑products (bran, pollard, hominy meal, mill-run) high in NSC (see Table 3), and 3–5% molasses, pushing up the NSC content. Heat processing improves starch digestibility in the small intestine but exacerbates insulin resistance and increases lactic acid production in the hindgut. Prepared feeds should therefore be used cautiously.

The popularity of “senior” feeds reflects how willing owners are to invest in their older horses’ health. However, studies show no significant differences in digestibility or body condition between mature horses (5–12 years) and older horses (19–28 years) when both receive good dental care and parasite control and are fed the same diet. While dental issues or reduced pancreatic function can affect nutrient absorption in some individuals, age alone does not appear to significantly reduce digestive efficiency. When their nutritional needs are met, many older horses can maintain good body condition well into their twenties and even thirties.

Table 3. NSC in Feed

Practical Feeding Guidelines for Older Horses

Healthy older horses generally do well on a normal adult diet, including:

• Good quality hay or roughage (30–35% Acid Detergent Fibre)

• Approximately 50% lucerne + 50% grass/oaten hay or chaff

• Total intake of 1.5–2.5% of bodyweight

• Ad‑lib water and salt

• A well‑formulated vitamin and mineral balancer

• While feeding lucerne to older horses can be controversial, its higher protein and leucine content means it can help maintain muscle mass better than grass hay.

Additional useful feeds include:

• Beet pulp (1–3 kg/day) as a fermentable fibre source

• Oils rich in omega‑3 fatty acids (canola, linseed), starting at 50 ml/day and gradually increasing to 500ml are anti-inflammatory.

Thermoregulation, Hydration, and Management

Older horses may have reduced ability to cope with heat and cold due to decreased blood volume. Despite reduced exercise tolerance, many horses in their twenties and thirties can maintain good body condition and continue athletic work without specialised feeding or training.

Management strategies include:

• Clipping in Summer and clipping and rugging in Winter

• Ensuring adequate salt and electrolyte intake

• Providing electrolyte paste with free access to water before travel promotes hydration and reduces the risk of impaction colic.

Body condition should be monitored. Cold conditions are harder on horses with a BCS <4/9, and loss of social position and bullying can occur in groups of horses. Managing horses individually, providing appropriate nutrition and veterinary care, with regular anthelmintic (horses 20–33yo have higher strongyle egg counts than 5–15yo) and dental treatment is a sound approach. Selecting feedstuffs carefully and feeding 3–4 meals improves digestibility, better matches normal feeding behaviour and minimises post-prandial glucose and insulin responses.

Weight loss can be a problem for some horses. Fat is the energy source of choice - high energy density and minimal risk of digestive upset. Canola and linseed provide omega-3 benefits and up to 800ml/day can be fed.  Horses may require 21 days to adjust to a fat-supplemented diet.  Omega 3 oils improve blood oxygen levels and reduce the incidence and severity of arthritis and inflammatory skin conditions in both humans and animals.

Table 4. Estimated increase in energy needed to increase condition score from 4 to 5/9.

With few exceptions and as in most species, whatever gets worse with age gets better with exercise. Provided horses are free from lameness and in good health, they should be able to sustain a moderate conditioning program.  Experienced, well-schooled horses can often maintain fitness with a lower volume of work and this helps reduce stress on the musculo-skeletal system. If a horse has been spelled or retired for some time, it’s worth having a veterinary examination before beginning a training program.

Exercise helps maintain joint function and slows the progress of certain diseases, whereas inactivity can worsen the severity. Although some level of aches and pains is normal with advancing years, there are medications and specialist shoeing techniques that can minimise the impact of age-related degenerative conditions such as navicular disease and arthritis. Osteoarthritis is a common cause of lameness and poor performance in horses of all ages, and degenerative joint disease a frequent reason for euthanasia. There are demonstrated benefits in providing chondroproetective compounds such as glucosamine, chondroitin and hyaluronic acid, and recently turmeric has consistently been found to be very useful in slowing all kinds of age-related changes.

Many old horses do not need special feeds or rations as a consequence of age alone and most old horses, especially those in their early 20s, can be fed adult (not geriatric or senior) prepared feeds. With thought and attention to detail, nutrition can be used to assist in maintaining health and exercise capacity. Managing horses individually, providing appropriate nutrition and veterinary care, with regular anthelmintic (horses 20–33yo have higher strongyle egg counts than 5–15yo) and dental treatment is a sound approach. Selecting low NSC feedstuffs carefully and feeding 3–4 meals/day, better matches normal feeding behaviour and minimises glucose and insulin responses to a meal. For performance horses, maintaining body condition is the minimum requirement of feeding. But the effects of ageing can be minimised and performance can be improved through nutrition. 

Dr Jennifer Stewart
BVSc BSc PhD Equine Veterinarian and Consultant Nutritionist