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SPILLERS puts senior science into practice

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SPILLERS™ is helping horse owners of older horses and ponies benefit from research on senior nutrition by putting the latest science into practice. Some of the latest collaborative work includes a potentially ground-breaking study 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 wellbeing, 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 include:

Short journeys may cause stress in seniors

It’s 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 1.5-2 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 doesn’t seem to affect the senior horse’s ability to digest nutrients when fed sufficient 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 & sugar based feed or hay plus a fibre & 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.

LLEP Healthy Horse Club members have access to unlimited virtual consults with our Registered Veterinary Nurse. Find out more:

References to work mentioned above

  • Dougal, K., de la Fuente, G., Harris, P.A., Girdwood, S.E., Pinloche, E., Geor, R.J., Nielsen, B.D., Schott II, H.C., Elzinga, S. and Newbold, C.J., (2014). Characterisation of the faecal bacterial community in adult and elderly horses fed a high fibre, high oil or high starch diet using 454 pyrosequencing. PloS one, 9(2), p.e87424
  • Elzinga, S., Nielsen, B.D., Schott II, H.C., Rapson, J., Robison, C.I., McCutcheon, J., Harris, P.A., Geor, R (2014) Comparison of Nutrient Digestibility Between Adult and Aged Horses Journal of Equine Veterinary Science, 34 (10), pp. 1164-1169.
  • Elzinga S Nielsen BD Schott HC Prapson J Robison CI Mc Cutcheon J Geor R Harris PA (2017) Comparison of nutrient digestibility between three diets for aged and adult horses DOI: http://dx.doi.org/10.1016/j.jevs.2017.03.126 Journal of Equine Veterinary Science, Vol. 52, p89
  • Galinelli N.,  Bailey S., Bamford N., Harris P.  Nutritional considerations for the management of equine pituitary pars intermedia dysfunction Equine Veterinary Education in press
  • Herbst, A.C., Johnson, M.G., Gammons, H., Reedy, S.E., Urschel, K.L., Harris, P.A. and Adams, A.A., (2021). Development and evaluation of a muscle atrophy scoring system (MASS) for horses. Journal of Equine Veterinary Science, p.103771
  • Jacob, S. I., Geor, R. J., Weber, P. S. D., Harris, P. A. and McCue, M. E. (2018), Effect of age and dietary carbohydrate profiles on glucose and insulin dynamics in horses. Equine Vet J. 50: 249 - 254. https://doi.org/10.1111/evj.12745
  • Jacob S.I., Geor R.J, Weber P.S.D., Harris P.A., McCue M.E. (2018) Effect of dietary carbohydrates and time of year on adrenocorticotropic hormone (ACTH) and cortisol concentrations in adult and aged horses. Domestic Animal Endocrinology, 63, 15-22
  • Macon, E.L., Harris, P., Bailey, S., Barker, V.D. and Adams, A., (2021). Postprandial insulin responses to various feedstuffs differ in insulin dysregulated horses compared to non‐insulin dysregulated controls. Equine Veterinary Journal in press
  • Miller AB, Harris PA, Barker VD, Adams AA (2021) Short-term transport stress and supplementation alter immune function in aged horses. PLoS ONE 16(8): e0254139. https://doi. org/10.1371/journal.pone.0254139
  • Morrison PK , Newbold CJ ,   Jones E ,   Worgan HJ,  Grove-White DH,  H. Dugdale AH ,  Barfoot C , Harris PA  & Argo CM (2018) The equine gastrointestinal microbiome: Impacts of age and obesity. Front. Microbiol., 07 December 2018 https://doi.org/10.3389/fmicb.2018.03017
  • Rapson J.L. , Schott II H.C. , Nielsen B.D. , McCutcheon L.J. , Harris P.A. &  Geor J.  (2018) Effects of age and diet on glucose and insulin dynamics in the horse. Equine Veterinary Journal https://doi.org/10.1111/evj.12812