Researchers shed new light on laminitis risk factors

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It may soon be easier to identify horses at greater risk of developing pasture-associated laminitis, new research suggests.

Horse owners and their veterinarians could do so by not only looking at breed type, body condition score and associated higher-risk environments, but by checking hormone and insulin levels.

Laminitis manifests in the foot and results in varying degrees of pain, lameness and debilitation. There are several causes, divided into three main categories: sepsis/systemic inflammatory conditions; endocrine/metabolic disturbances, which include pasture associated laminitis; and mechanical overload.

Being able to identify animals at increased risk of laminitis, as well as the potential risk factors, is obviously key to reducing the incidence of the condition.

Two new studies conducted in collaboration with the Waltham Equine Studies Group have cast new light on the issues involved.

The first, carried out by Nanna Luthersson and colleagues and published online in the Journal of Equine Veterinary Science in March, evaluated the laminitis risk factors in a group of Danish horses and ponies.

It confirmed that cold-blooded type horses under 149cm at the withers, such as certain native ponies, as well as those being kept on high quality pasture, were at an increased risk of developing laminitis for the first time. It also highlighted the important role that a change in grass intake, in terms of both type and amount, may play at any time of the year, not only in the spring as commonly thought.

The second study was undertaken in conjunction with Nicola Menzies-Gow, from Britain’s Royal Veterinary College, and was published online in the Equine Veterinary Journal in August.

The study evaluated the risk factors for the development of laminitis prior to the occurrence of the disease.

It identified that low concentrations of the fat-tissue derived hormone adiponectin, together with high serum insulin concentrations (at rest and as part of a diagnostic test for Cushing’s disease) may predict an increased risk of future pasture-associated laminitis.

It is hoped that future studies will be able to generate more robust cut-off values, which will more accurately predict future laminitis development in an individual animal.

The Royal Veterinary College, working with Waltham, is currently taking this forward through a study in which these markers are measured regularly, in conjunction with a detailed management assessment, in a group of ponies with no known history of laminitis at the start.

Registered nutritionist Clare Barfoot, the research and development manager at British feed manufacturer Spillers, said the Danish study provided important practical facts about the susceptibility of cold-blooded types, and was particularly applicable to natives in Britain.

The second study gives hope that there may soon be a test or series of tests that will help predict horses at an increased risk of suffering from pasture-associated laminitis in the future, potentially reducing the number of animals affected by the debilitating condition.

In the meantime, until there is a full understanding of the condition, it is considered sensible to manage all the risk factors that are currently known, in particular keeping horses at a healthy weight.

Barfoot offers the following tips to help keep horses safe from laminitis all year round:

  • Do not turn out cold-blooded types on to new, high quality pasture.
  • Restrict grass intake. Even winter grass can be a significant contributor to excess calories. A horse or pony can consume up to three times its normal daily energy requirement in just 24 hours at grass. Consider using an appropriately fitting grazing muzzle for part of the day and/or restrict time out at grass, although body condition still needs to be monitored as some animals can still consume a considerable amount in a short period of time.
  • Keep regular track of each horse’s body condition.
  • Increase exercise if appropriate to do so, not only to help the horse or pony lose or maintain a healthy weight but also to help keep the metabolism healthy.
  • Provide an appropriate amount (not less than 1.5% bodyweight per day on a dry matter basis) of an alternative low-calorie forage source. Replacing pasture with suitable (less than 10% (on a dry matter basis) water soluble carbohydrate, WSC) hay, haylage or a forage replacer will help replicate natural browsing behaviour whilst controlling calories and WSC intake.
  • Avoid feeding cereals or cereal based feeds, opt for a balancer or if additional calories are required look for a high oil, high digestible fibre, low starch and sugar option.
  • Provide daily vitamins and minerals to balance the diet; an appropriate feed balancer is ideal for this purpose.
  • Don’t over-rug overweight horses and ponies, especially if they are natives or unclipped. Let them burn calories to keep warm.

Luthersson N, Mannfalk M, Parkin TDH, Harris P, Laminitis: Risk factors and outcome in a group of Danish horses, Journal of Equine Veterinary Science (2016), doi: 10.1016/ j.jevs.2016.03.006.

Menzies-Gow N.J, Harris P.A. , Potter K. and Elliott J. (2016) Prospective cohort study evaluating risk factors for the development of pasture-associated laminitis in the UK EVJ Version of Record online: 25 AUG 2016 | DOI: 10.1111/evj.12606

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