Some of the latest collaborative work by SPILLERS includes a potentially ground-breaking research to improve the understanding of pars pituitary intermedia dysfunction (PPID).
SPILLERS, via the WALTHAM Equine Studies Group, is involved with numerous research collaborations which bring together world-leading equine veterinary, nutrition and research experts to support the well-being, performance and longevity of senior horses and ponies.
“Here at SPILLERS senior horses hold a special place in our hearts; we have been involved in senior horse research for more than twenty years,” said Sarah Nelson, SPILLERS product manager. “By translating our science and sharing highlights and practical take home messages we hope to give the owners of seniors the extra support they need to help keep their horses in the best possible health.”
Practical translations of the latest research the five topics are discussed below.
Short journeys may cause stress in seniors
It is well known that long distance transport increases stress and compromises immune function, but what about the effects of shorter journeys on seniors, given that we know ageing can lead to low grade inflammation?
A recent study in senior horses found that travelling for one and a half to two hours in a trailer increased certain markers of stress and inflammation. More work is already underway to help better understand the practical implications of this.
Ageing does not seem to affect the senior horse’s ability to digest nutrients when fed sufficiently to maintain bodyweight
A SPILLERS study 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). Similar findings were found in another of our studies with ponies.
A follow up study also showed there was also no effect of age on mineral digestibility in horses.
Older horses may be more sensitive to changes in diet
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.
Restricting starch and sugar may be beneficial to seniors
Insulin dysregulation (which includes a high basal insulin, and/or 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 studies which investigated the relationship between age, diet and insulin dysregulation found that even healthy senior horses typically have an increased insulin response to a meal high in starch and/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.
SPILLERS is currently working hard to refine guidance on the level of starch and sugar to be fed to older equines with insulin dysregulation, and a study on this topic is due to be published in the Equine Veterinary Journal shortly.
High starch diet could potentially lead to a false 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, research has shown that a high starch diet can also increase the concentration of ACTH in the blood which could potentially lead to a misdiagnosis of PPID.
Future studies
SPILLERS has an exciting new collaborative research project in the pipeline to help improve of the understanding and knowledge of the causes of PPID as well as early diagnosis, treatment, husbandry and nutritional management.
The findings from a number of other collaborative research projects that will be shared shortly, include:
- Investigation of the primary use and current exercise regimen of US senior horses
- Risk factors and reasons for retirement
- Prevalence, risk factors for and consequence of low muscle mass in this population
- Development and evaluation of a muscle atrophy scoring system (MASS) for horses
SPILLERS’ Equine Clinical Nutrition Specialist Pat Harris is continuing to share the latest work on senior nutrition by giving talks and delivering practical CPD courses to vets around the world. Pat is also co-author of a paper to be published shortly in Equine Veterinary Education on nutritional considerations for the management of equine PPID.
“We are committed to improving the health and welfare of senior horses,” said Sarah. “Our aim is to always be your trusted partner in care, to help them and you to enjoy their precious twilight years.”
For more advice on feeding your senior horse or pony contact the SPILLERS Care-Line on 01908 226626.
