Diagnosing Insulin Resistance: Q&A with Researchers

Thehorse.com - Full Article

by: Kathryn Watts, BS
August 28 2008, Article # 12588

Over the past few years researchers have described a strong association between insulin resistance and laminitis in equines. They are working now on defining standard testing protocols and interpretations to identify horses at highest risk for laminitis. Many questions remain unanswered. How should insulin resistance be defined and diagnosed? How do researchers interpret test results? Can blood tests alone determine the risk of our horse or pony to get laminitis? Until they have more solid science to configure a standard definition of equine insulin resistance, those attempting to define it might find themselves in the same predicament as the proverbial group of blind men describing an elephant.

A study in the United States showed that laminitis affected 2% of all horses, with the incidence going up to 5% in spring, which is when grass sugars peak. The ability to identify high risk animals before laminitis strikes is essential, as this can allow caretakers to implement appropriate management practices to prevent it. Sinking or rotation of the coffin bone requires treatment and rehabilitation regimes that can be difficult, long, expensive, and emotionally draining. Even then, the treatments often fail. But how do we identify the high-risk animal? Of course any horse that has had a brush with laminitis should have tests for underlying endocrine problems, but certain physical characteristics should lead proactive owners to test for insulin resistance.

A "cresty neck" is the classic sign of insulin resistance, and researchers note a solid correlation between neck circumference and the condition. Horses that gain weight much more quickly, often described as "blowing up on grass" than their herdmates under similar management, might be candidates for testing, especially if they also exhibit signs of foot tenderness. Additional signs are rings on the hoof wall, or a stretched white line with blood specks when the foot is viewed from the bottom, both which could be indications of a previous mild case of laminitis...

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