Senior horses hold a special place in our hearts and as part of our commitment to improving their health and welfare, we have been involved in senior horse research for over twenty years. Here we share a few of our key highlights and news of one of our latest projects…

Does aging affect your horse’s ability to digest nutrients?

A study we published in 2014 found that in healthy horses, age ‘being senior’ did not affect energy, protein or NDF (fibre) digestibility regardless of the type of diet fed (hay only, hay plus a starch & sugar based feed or hay plus a fibre & oil based feed). A follow up study showed there was also no effect of age on mineral digestibility.

Gut bacteria

The horse’s hindgut is home to trillions of tiny microbes including bacteria, viruses and fungi which are essential for fibre digestion and helping to regulate the immune system. Research in healthy horses found that ageing led to a reduction in the diversity of hindgut microbes, which may make some older horses more sensitive to changes in diet. 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 may suggest that ponies ‘age later’ than horses.

Insulin response

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 and is associated with an increased risk of laminitis. However, two of our studies which investigated the relationship between age, diet and insulin dysregulation found that healthy senior horses had an increased insulin response to a meal high in starch or sugar. This suggests that restricting starch and sugar intake may be beneficial for all senior horses, regardless of whether or not they have PPID or a history of laminitis.

Diet & PPID diagnosis

Diagnosis of PPID involves a blood test which measures the level of adrenocorticotropic hormone or ‘ACTH’ in the blood. Diagnosis can be notoriously difficult because ACTH levels can be affected by several factors including the time of year and even ageing itself. However, our research has shown that a high starch diet can also increase the concentration of ACTH in the blood which could potentially lead to a false diagnosis of PPID.

NEW research: travelling stress

It’s well known that long distance transport increases stress and compromises immune function, but what about shorter journeys? Ageing can lead to low grade inflammation and many senior horses that are still in work regularly travel short distances. A recent study in senior horses found that travelling for 1.5-2 hours in a trailer increased certain markers of stress and inflammation. More work is already underway to help us better understand the practical implications of this and to further investigate the possible benefits of targeted supplementation.

What’s next?

We are currently involved in a major international project that aims to improve the understanding and knowledge of the causes of PPID and in turn, improve early diagnosis, treatment, husbandry and nutritional management. If you were one of the horse owners who completed the recent PPID survey (which was one of the first stages of the project) shared on our Facebook page, you will have already helped us in our quest to improve the health and welfare of horses and ponies with PPID around the world! We promise to keep you updated as this multi- year project progresses so watch this space!

For more advice on feeding your senior horse or pony contact the SPILLERS Care-Line