Photo: Michael Raine.

WCVM scientists assist in laminitis puzzle

Laminitis research for the layman can be divided into two broad topics: therapies that can be used to treat laminitis and investigations into the chain of signalling events that trigger the condition (new targets for future therapies).

Researchers at the Western College of Veterinary Medicine (WCVM) are tackling both aspects. Two of the veterinary college's scientists — Drs. David Wilson and Baljit Singh — talked about their laminitis investigations during a special equine education event at the WCVM in September 2012.

"Other than recent discoveries about cold, I'm not convinced after 30-plus years that once the process of laminitis starts, if there's anything much we can do to stop the acute chain of events," said Wilson, a large animal surgeon and professor in the WCVM's Department of Large Animal Clinical Sciences.

Some of his research looks at the specifics of treating laminitic horses with cold therapy. "We know how cold feet are in an ice bath," says Wilson. "Now we need to know how cold they need to be to prevent laminitis."

The WCVM researchers are also trying to establish parameters for how long the cold therapy should be applied. One study performed during the summer using a 72-hour ice bath model consumed in excess of 1,200 lbs of ice for two horses — not entirely practical for application to clinical cases.

In addition, Wilson's research team is testing the Game Ready ™ Equine System, a system that wraps around the horse's leg and delivers dry cold and active compression.

A research team led by Singh is investigating the chain of cellular reactions that lead to laminitis (known as a trigger pathway). It's an important piece of the larger puzzle of how horse owners and veterinarians can prevent laminitis in the first place.

Singh, a professor in the Department of Veterinary Biomedical Sciences and associate dean of research at the WCVM, studies endotoxemia. This critical health issue happens when the circulating blood is contaminated with endotoxin.

Endotoxin is released from bacterial cell walls when the cells die in horses with infections of organs (such as the lungs or liver) or in colic conditions when the intestinal wall is compromised — allowing absorption of bacterial toxins from the intestinal lumen.

After studying endotoxemia and inflammation in the lungs, Singh is now looking at whether the lungs might play a role in laminitis.

"We are trying to understand the relationship between inflammation in the lung and laminitis," Singh explains. "The lung interfaces with all of the blood in the body — it comes out of the heart, into lungs, then into general circulation. The digital laminae see only a fraction of total blood volume; it's the liver and the lung that filter out all the endotoxins."

If the horse's filtering organs become overwhelmed, it can trigger inflammation in various parts of the body. Organs such as the lungs, the digestive tract and the laminar tissues deal with this inflammation in different ways with varying degrees of success.

"The horse's gut gets inflamed all the time," Singh explained in his lecture. "It understands how to manage inflammation. The digital laminae do not know how to manage it."

Singh and his research team have collected tissue samples from their first set of experiments and are working on analyzing data. Based on the findings, there are plans for further experiments in the future.

Wilson is looking at similar relationships between the equine hind gut and the endotoxemia process. His work is based on research indicating that streptococcal bacteria present in the hind gut may induce the dissolution of laminar membranes.

Wilson is now looking at what kinds of bacteria are present in the hind gut at different points along the endotoxemia spectrum — and how that bacteria may be absorbed into the bloodstream.
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