Friday, July 11, 2014

Grass's (Missing) Link to Laminitis: Hormonal Imbalance Sets the Stage for Disease

For years, laminitis has been characterized as a disease of the horse's foot. Treatment has centered on relieving pain to the foot and facilitating healthy new growth. But just as important is understanding what caused the laminitis to occur and treating laminitis as a disease of the entire horse, not just the feet. (HC Biovision photo of a laminitis-ravaged horse foot by Dr. Christoph von Horst)
Just when you thought laminitis research was starting to make some sense, the landscape changes. If you haven't been keeping up with laminitis research for the past few years, you've missed grass being given a get-out-of-jail-free card for its lack of a direct role in causing laminitis.

It causes a spike in insulin, which can lead to laminitis, but grass does not directly cause laminitis.

If you have been keeping up with the research, this article won't be news at all.

But unfortunately, not everyone has been receiving the same information at the same time.

While there is no question that lush grass in spring and fall can cause a triggering response in the hormones of some horses that leads to laminitis, we're now being asked to look beyond the grass itself and at the horse's hormonal system to understand how, why and if laminitis will result when a horse has been grazing.

There are other causes of laminitis, of course, but studies are proving that underlying hormonal imbalance precipitates the most common forms of laminitis we see in horses.

This video is a clip featuring Andy Durham from an early educational webinar on laminitis sponsored by Boehringer Ingelheim. The pharmaceutical company has sponsored a great deal of research into hormonal testing and the endocrinopathic forms of laminitis.

Professor Andy Durham, Liphook Equine Hospital and visiting professor at the new University of Surrey School of Veterinary Medicine, United Kingdom, will present his latest research on the hormonal predisposition to the disease at the Equine Veterinarians Australia (EVA) Bain Fallon conference on the "Gold Coast", from the 13th to 17th of July.

His research has focused on the probability that horses can be identified as being at risk for the disease, just as humans can be identified as potentially at risk for developing a similar condition.

Professor Durham says that metabolic syndrome, a problem that includes insulin resistance, has progressed into the greatest threat to human health in the developed world and is a consequence of readily available high calorie food and drink, containing refined sugars, alongside a more sedentary lifestyle.

“It should come as no surprise that this same concept applies to horses and is referred to as equine metabolic syndrome (EMS).

“The major consequence of EMS in horses is laminitis, a metabolic condition that affects the whole body but is expressed in the feet of a horse,” he said.

“Over the last few years our attitude towards the cause of laminitis has changed dramatically. We’ve always known that an older, overweight pony is more susceptible to the disease than a younger thoroughbred, and it was always thought that eating excessive amounts of lush grass, high in simple sugars was the main culprit of laminitis.

“However recent research evaluating grass intake in grazing horses and ponies has put a different slant on this theory.

“There have been two studies undertaken in the last few years investigating the underlying causes of laminitis in a variety of horses. In both studies, around 90 per cent of confirmed cases were associated with an underlying endocrine (hormonal) disorder. Some presenting with Cushing’s disease (an overproduction of cortisol) and some with equine metabolic syndrome.

“So when horses and ponies with an underlying hormonal disease graze and ingest sugars (simple sugars, fructans and starch) from the grass, this stimulates abnormally high levels of insulin.

“In normal horses, without an underlying hormonal disease, grazing pasture is unlikely to lead to insulin levels high enough to cause laminitis.”

Professor Durham said that while treatment is extremely important, lifestyle and dietary management is the key to reducing the incidence of the condition.

“The long-term feeding of sugar- and starch-based feeds, particularly to overweight ponies and horses can lead to development of insulin resistance. So proper nutrition, exercise and weight management is important in preventing the disease,” he said.

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In summary, here's Dr. Don Walsh of the Animal Health Foundation, a leading funding resource for laminitis research, reviewing the prevention protocols for the main types of laminitis, including endocrinopathic. This is the fifth and final video in the AHF 5-part laminitis video series, which is available on YouTube and highly recommended for any who needs information on the disease.

But this video says a great deal in a few short minutes:

Click to watch the whole series (approximately 30 minutes).

Note: While many horses are predisposed to laminitis because of a hormonal condition, the many other causes of laminitis can still wreak havoc with a horse's feet and even be complicated by the type of hormonal problems described by Andy Durham. Retained placenta, support limb overload, medication reactions, colic and surgery recovery, colitis and any number of fever-related and unusually stressful conditions can still lead to laminitis. 

Thanks to the Australian Veterinary Association for a media release that inspired this article. Quotes from Andy Durham were from AVA.

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