Breakthrough in ultrasound technique for horses

March 30, 2007

by Rachelle Cooper,
Equine Guelph


Prof. Heather Chalmers, Clinical Studies, says she couldn't be happier working at OVC.
Picture: Barry Gunn

Research by radiology specialist Prof. Heather Chalmers has led to a new ultrasound technique for horses' throats that could lead to better understanding of upper-respiratory diseases and allow racehorse owners to know if their horse could develop future airway problems.

Her breakthrough development was published in the fall 2006 issue of Veterinary Radiology and Ultrasound.

"Racehorses get a number of diseases of the throat that limit their performance and tend to have an impact on the value of the horse, its career and lifespan," she says. "The equine laryngeal ultrasound could allow us to advise owners or buyers of horses about what the future airway performance of a horse may be."

Ultrasound has been used to assess throat conditions in people, dogs and cats, but until now, the only way to assess a horse's throat was by videoendoscopy - inserting a small fibre-optic camera through the animal's nose to look into its larynx.

"The accuracy of upper-airway endoscopy is less than desirable for many important conditions," says Chalmers. It's also more invasive than an ultrasound.

She sees the ultrasound working as a complementary diagnostic tool to endoscopy and as a means of refining research around upper-respiratory problems. Ultrasonography can image structures that can't be detected with endoscopy.

"Without knowing anything about the history of a horse, I can tell you with reasonable accuracy what its problem is by ultrasound alone," says Chalmers, who has examined more than 100 horses with throat problems to determine the efficacy of ultrasound as a diagnostic tool.

Her findings have already generated a lot of international interest because this new tool could have a big impact on the economy of the horse industry.

"Buyers could spend anywhere from $100,000 to $2 million for a thoroughbred yearling that's never even hit the track," she says. Information about the horse's future health is crucial in the decision to purchase a yearling.

Chalmers is now collaborating with a group from Norway using ultrasound to investigate a throat condition found only in the Norwegian cold-blooded trotter.

Because it's just been developed, laryngeal ultrasound isn't currently part of the training received by veterinary radiologists, but "among ultrasonographers, it's a technique that could be learned," she says.

At OVC, Chalmers spends half of her time in the clinic and half doing research and teaching. As a radiologist, she sees both large and small animals that come into the clinic.

"I see whatever comes through the door that day. We get everything from horses, cattle, dogs and cats to ferrets and reptiles that can require an X-ray, nuclear medicine procedures, ultrasound or MRI."

Originally from London, Ontario, Chalmers earned both her undergraduate biomedical sciences and DVM degrees at Guelph, then completed a residency in radiology at Cornell University.