Did you know that through our work with the WALTHAM Equine Studies Group, SPILLERS has been involved in laminitis research for over twenty years? We hope that by developing a better understanding of what causes laminitis, we can ultimately help to prevent laminitis in the future. With laminitis season now upon us we thought it timely to share a few of our recent highlights along with an insight into some our current work…

Recent highlights

- Excess weight gain as result of feeding cereals was found to reduce (tissue) insulin sensitivity whereas weight gain as result of feeding fat/ oil did not. This research suggested that the source of excess calories rather than obesity per se may have a greater effect on insulin sensitivity.

- A recent change in grazing, a move on to ‘good quality’ grazing and being a pony of cold blood breed were found to risk factors for laminitis regardless of the season.

- High levels of insulin and low levels adiponectin (a hormone secreted by fat cells that helps to regulate glucose and fat metabolism) in a single blood sample were able to retrospectively predict the risk of laminitis.

- A study found that the threshold levels used for interpreting the combined glucose/ insulin tolerance test (a test used for diagnosing insulin dysregulation) need to the adjusted for ponies.

- Increasing the dose of Karo Syrup used in the Oral Sugar Test (OST), another test used for diagnosing insulin dysregulation, was found to better differentiate between previously laminitic and non-laminitic ponies.

- A study found that the current dose of Karo syrup used in the OST may not be high enough to detect effectively detect insulin dysregulation some horses.

- Insulin response to the OST was found to be lower in autumn, suggesting that seasonally adjusted reference ranges (which are used to interpret results of the OST) may be needed when testing for insulin dysregulation.

- Insulin-like growth factor 1 (IGF-1: a growth hormone) was identified as a possible link between high levels of insulin in the blood and laminitis. The surface of lamellar cells in the hoof appear to contain no or very few insulin receptors which had left scientists confused about how high levels of insulin may lead to laminitis. However incubating lamellar cells with increasing concentrations of insulin caused a cross reaction with IFG-1 receptor cells. Furthermore, this could be prevented with an antibody that specifically blocks IGF-1 receptors only. Although more work is needed, this research suggests that targeting IGF-1 receptors may be an option for treating or preventing laminitis in the future.

Current research

We are far from having all of the answers and continue to participate in several areas of laminitis research including:

- Barriers to implementing evidence based management practices: In order for scientific research to benefit horses and ponies, effective communication of the results and their significance is essential. Current research is investigating the reasons why evidence based management practices may or may not be implemented by horse owners.

- Predicting laminitis risk: In follow-up to our previous work, we are now hoping to improve our ability to predict laminitis risk by following a group of previously non-laminitic ponies every 6 months. In addition, a PhD project part funded by the WALTHAM Equine Studies Group aims to identify faecal microbiome patterns and/ or urinary markers that may be able predict the risk of pasture associated laminitis.

For more advice on feeding horses and ponies prone to laminitis contact the SPILLERS Care-Line on 01908 226626

References

Bamford, N. J., Potter, S. J., Baskerville, C. L., Harris, P. A., & Bailey, S. R. (2016). Effect of increased adiposity on insulin sensitivity and adipokine concentrations in different equine breeds adapted to cereal-rich or fat-rich meals. The Veterinary Journal214, 14-20.

Menzies-Gow N.J, Harris P.A., Potter K. and Elliott J. (2017) Prospective cohort study evaluating risk factors for the development of pasture-associated laminitis in the UK EVJ (49). 300 – 306

Luthersson N, Mannfalk M, Parkin T. D. H. & Harris P (2017).  Laminitis: Risk factors and outcome in a group of Danish horses Journal of Equine Veterinary Science 53 June 68 -73

Morrison P.K., Dugdale A.H.A, Grove-white DH, Harris P.A., Barfoot C.F & Mcg Argo C (2017) Repeatability of the combined Glucose/insulin test in ponies of the same breed and gender, across time Journal of Equine Veterinary Science, 52, p57.

Baskerville C.L., Chockalingham, S., Harris, P.A., Bailey S.R. (2018). The effect of insulin on equine lamellar basal epithelial cells mediated by the insulin-like growth factor-1 receptor. PeerJ 6:e5945  (DOI 10.7717/peerj.5945).

Macon, E. L., P. A. Harris, V. D. Barker, S. Elzinga, A. A. Adams. (2019). Insulin dysregulation and healthy horses’ seasonal insulin responses to the oral sugar test. 26th Equine Science Society Symposium, Asheville, NC, June 3 – 6 2019 Journal of Equine Veterinary Science 76 p 38

Macon, E. L., P. A. Harris, V. D. Barker, S. Elzinga, A. A. Adams. (2019). Insulin dysregulation and healthy horses’ seasonal insulin responses to the oral sugar test. 26th Equine Science Society Symposium, Asheville, NC, June 3 – 6 2019 Journal of Equine Veterinary Science 76 p 38