A few years ago, a magazine article describing a minimally-invasive treatment for people with chronic sinusitis caught the eye and imagination of Chris Bell, DVM. What if such a treatment could be adapted for use in horses?
Last summer, the chance to test that theory came up for Bell when second-year veterinary student Dane Tatarniuk began working on a project to define the bony anatomy of the horse's sinus.
"Dane was able to show through the anatomical dissections that there are two separate nasal maxillary openings--something that's never been previously reported," pointed out Bell, a large animal surgical resident at the Western College of Veterinary Medicine and a research fellow with the College's Equine Health Research Fund.
Out of that information emerged the development of a new, minimally invasive treatment for sinusitis--a common condition that can have an enormous impact on horses. "If it isn't treated, it causes a chronic infection in the sinus which results in performance-limiting nasal discharge," explained Bell. "It can actually deform the bone and affect all the soft tissues surrounding the sinus cavity."
Primary sinusitis, caused by bacterial infection, has traditionally required surgery using general anesthetic. "We actually flap the bone back and then go in surgically and punch a hole down through the sinus to provide drainage and to flush it," described Bell, adding that patients usually spend about five days in the clinic recovering from this invasive surgery.
Now, this new procedure will decrease the recovery time and minimize the effect on the animal--addressing key concerns for horse owners and veterinarians.
"The major advantage is that it's minimally invasive and it can be done in the field. It'll provide the ability for a practitioner to possibly treat sinusitis in the field without the horse having to come in to a veterinary clinic," Bell said.
Balloon catheters: from humans to horses
Bell and Tatarniuk began their research trial with the guidance of Bell's graduate supervisor, James Carmalt, MA, VetMB, MVetSc, MRCVS, Dipl. ABVP, ACVS. Their first step was using an endoscope to determine the exact location of the nasal maxillary opening. "That hadn't been really defined in equine surgery anywhere," Bell said.
Dane Tatarniuk (left) watches as Dr. Chris Bell uses a horse's skull to demonstrate how the human esophageal dilation balloon catheter (see closeup) is inflated inside the sinus cavity.
Pinpointing the opening's location would allow them to accurately insert a balloon catheter and dilate the opening under endoscopic guidance, a similar procedure to that used in humans. To learn more, Bell spent a day in the Royal University Hospital's cardiology catheterization laboratory in Saskatoon where he watched procedures and gained valuable advice from lab director Dr. Colin Pearce and his staff.
After considering a couple of options, Bell found that a human esophageal dilation balloon was the right size and strength for the equine procedure. The RUH staff helped him to determine the optimal inflation for the balloon, and he and Tatarniuk began testing the model on horse skulls.
"We would fill both sides of the sinuses with fluid. We wouldn't use the balloon catheter on one side, and then we'd balloon catheterize the other side. This allowed us to compare the drainage rates between the two sides," Bell said. Through these experiments, they discovered that inserting the balloon catheter permanently dilated the opening and allowed for increased drainage.
Novel use for AI pipette
However, there was a problem with the endoscope: it was just too flexible. What they needed was a rigid introducer that could withstand the back pressure of the catheter moving past the cartilage. Unfazed, Bell ingeniously fashioned a device by shaping and moulding a pipette used for artifical insemination (AI). "Now we run our balloon up through this introducer. It has nowhere else to go but right inside there," Bell said, adding that a patent for the introducer is now under review.
After perfecting the procedure on cadavers, Bell and Tatarniuk tried it out on live animals. "I was quite surprised," Bell said. "I thought they'd resist it a lot more as we were crushing some cartilage up in their sinuses, but we found that with basic sedation, they didn't resist the passage of the introducer. We were able to show that we can do these in the standing horses so they don't require general anesthetic."
According to Bell, the procedure has also proven useful in treating secondary sinusitis that often develops along with dental issues. Specifically, the technique is used for packing the sinus during surgery. "The advantage with our technique is that we don't have to make an extra hole. We just dilate the normal hole and pass the removable packing through. It's much better for the horse--the healing is a lot better, and the risk of introducing infection is a lot lower."
In October, Bell plans to present the research team's work at the American College of Veterinary Surgeons' annual symposium in Washington, D.C. Over the next year, he plans to carry out clinical trials to further confirm the results. "Basically, we're going to provide the same flushing as we would normally do except that I'll be able to pass the balloon catheter on the horses and monitor them."
The research project, which is part of Bell's Master of Veterinary Science (MVetSc) degree program, has been very satisfying. "The thrill of designing something new, coming up with something novel that hadn't been done before in horses and being able to adapt a human surgical technique for horses--that was probably what was the most fun about it."
Bell also enjoyed working with Tatarniuk. "He's a really good student, really keen, and he really impressed me." He added with a laugh, "I'd hire him if I had a clinic."
Lynne Gunville is a freelance writer and editor whose career includes 25 years of teaching English and communications to adults. She and her husband live at Candle Lake, Sask.
Reprinted with permission of Horse Health Lines, publication for the Western College of Veterinary Medicine's Equine Health Research Fund. Visit ehrf.usask.ca for more information.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.