The senior horse population across the developed world is increasing. In fact, it is now thought that up to one-third of the global equine population is older than 15 years of age. This longevity is primarily because of improved healthcare and nutrition. In addition, the reasons we keep horses have changed. The majority of horses and ponies in developed countries are now considered more pets than working animals.  

This means that we owners are much more committed to providing the best care we can to keep our older horses as fit and active as possible.  

But at what age should a horse be considered old? There are many conflicting opinions when it comes to age and aging. One thing we definitely know is that horse age is not just a number. 

Is Your Horse Considered a Senior? How Equine Age Is Measured

A horse’s age can be measured in three ways: 

  1. Chronological age, which is simply the horse’s age in years. This can give you some information, but it can also be misleading because some horses, just like people, age more or less successfully. We all know someone who is “old before his (or her) time” and others who seem to defy the passing years and remain more youthful. Horses are no different! 
  2. Physiological age uses markers of aging and might be the most accurate way to measure aging, but this whole area is still being researched. 
  3. Another way to look at age is demographically, using as a yardstick the age at which there is 25% survivorship within the overall population.  

Whichever way you measure age, one thing is for sure: It’s highly individual. Most owners use a combination of chronological and physiological age to “judge” whether their individual horses are senior and need a change in feed and/or management.  

In a recent survey completed by 2,212 owners/carers in the UK, 65% of respondents didn’t consider their horse as old until they had reached 20 years old (SPILLERS™ Senior Horse Survey, 2024) This number might be even higher in ponies.  

Signs of Horse Aging

Due to the very individual nature of aging, it’s important to keep an eye out for some of the signs that might indicate your horse or pony is starting to show its age. Some of these signs for a senior horse are discussed below. 

Changes in digestion and gut function. Other species, including rats and humans, show gut and gut-based immunity problems as a consequence of aging. Research published in 2014 found that in healthy horses, “being senior” did not affect energy, protein, or NDF (fibre) digestibility regardless of the type of diet fed (hay only, hay plus a starch and sugar-based feed, or hay plus a fibre- and oil-based feed). A follow-up study showed there was also no effect of age on mineral digestibility. This suggests that age per se doesn’t affect nutrient digestibility, at least for horses and ponies fed an appropriate diet. 

However, work undertaken by Dougal et al. in 2014 did show reduced diversity in bacterial species in the hindgut of aged horses. From a practical perspective this could mean that older horses might be more sensitive to dietary changes.  

Interestingly, no reduction in diversity was seen when this research was repeated in similarly aged ponies. Although the reasons for this are not yet clear, these findings might suggest that ponies “age later” than horses.  

Body condition and muscle tone. Many horse owners will tell you that their senior horses lose weight more easily and have lost muscle tone. However, these observations might not be a direct effect of aging.  

A reduction in exercise has a larger effect on muscle tone than aging per se. To help evaluate any potential muscle wastage use this muscle wastage scoring guide.

Regarding weight changes, equine obesity unfortunately brings just the same challenges to the senior horse population as it does to the general horse population. It might even have additional consequences for senior horses.  

Two surveys, one in the UK and one in the US, found that 10.5% and 28.0% respectively of the older horse population were overweight. This potentially increases their risk of age-related disease.  

Temperature control. Senior horses do not cope as well as younger horses with extremes of temperature. This is similar to the way that humans often become more sensitive to heat and cold as they age.  

So, in colder months, consider rugs, shelters, and stabling. During hotter months, concentrate on keeping older horses cooler with clipping, hosing down, and making sure they have appropriate shade. 

Immune defence. Horses, like humans, do show signs of age-related declines in immune function. This leaves them more susceptible to infections. This effect is exacerbated in overweight and obese horses, which is another reason to keep them lean! 

Dental issues. There is a saying that horses survive as long as their teeth. This is certainly true in the wild! In a domestic situation, dental issues are one of the main reasons for weight loss in older horses. Signs can include a lack of condition or digestive issues such as colic, choke, or quidding (spitting out partially chewed hay). Also of concern are bad breath, lack of appetite, long fibres in the droppings, or obvious pain and discomfort when eating and chewing. If these signs are not noticed, some owners will increase the amount of compound feed without addressing the underlying problem.  

Some dental issues can be resolved, but management of those that can’t depends on finding a way to appropriately replace the long fibre portion of the diet (which includes grass, hay, and haylage [silage made from partially dried grass]).   

Insulin dysregulation. Insulin dysregulation (which includes a high basal insulin, an exaggerated insulin response to consuming starch and/or sugar, and tissue insulin resistance) can be present in some horses with PPID. It is associated with an increased risk of laminitis.  

However, two of our studies that investigated the relationship between age, diet, and insulin dysregulation found that even healthy senior horses had an increased insulin response to a meal high in starch or sugar. This suggests that restricting non-structural carbohydrate (NSC)—or “starch and sugar intake”—might be beneficial for all senior horses, regardless of whether they have PPID or a history of laminitis.  

Joint disease. Pain from general joint disease—especially in the neck and/or forelimbs—can affect appetite as well as the horse’s desire to graze and eat from a hay net. 

Avoid turning senior horses out on hilly, uneven, or heavily poached (heavily worn) fields. Consider feeding from raised buckets/mangers. Discuss a pain management program with your vet to help maintain good welfare.  

Herd dynamics. As horses age, herd dynamics become increasingly important. Horses benefit in many ways by living in a herd environment. But as they get older, they might be pushed down the pecking order by younger animals. That means they might lose out when it comes to feed and water.  

Look out for signs of bullying, and feed horses separately if needed. Ideally, provide a large water trough or more than one water supply in the field. 

Summary: When It Comes to the Senior Horse … 

  • Treat all horses and ponies as individuals as they age. 
  • Monitor them regularly, as changes can occur rapidly but might also occur gradually. 
  • Familiarise yourself with the subtle signs of failing dentition and ill health. 

Further Reading

Resources

  • Clare Barfoot, RNutr
    Clare Barfoot is a registered equine nutritionist with the Association of Nutrition. She is Marketing and R&D Director for Spillers and oversees the nutritional management of all that company's products.
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