A safer solution for a sticky problem?
When my little dog Maggie was young, she would chew anything she could get her paws on: a lamp cord, cell phone charger, TV cable, garbage cans, clothing, the bathroom curtain and even the bottom of a door.
But most of all, she loved to gnaw on the pig’s hoof that I gave her to chew.
One day Maggie seemed “off.” After a series of X-rays, our local veterinarian discovered that a chunk of pig’s hoof was sitting somewhere in my miniature Australian shepherd’s small intestine.
Maggie’s story has a happy ending — the piece of hoof passed through her without surgery. But other chew-happy dogs aren’t so lucky: sometimes, swallowed objects can actually get stuck inside them.
One common “sticking spot” where foreign objects can become lodged is the esophagus right in front of a dog’s heart.
“Usually that specific spot is more commonly a problem with smaller dogs just because of the way their anatomy goes,” says Dr. Amanda Tallant, a surgical resident at the Western College of Veterinary Medicine (WCVM). “Bigger dogs usually get obstructions at different places.”
Most esophageal blockages are treated with endoscopy: veterinarians insert a tiny instrument into the dog’s esophagus and use it to push the foreign object into its stomach.
But if the object has been stuck there for a while, it may damage the dog’s esophagus. “The covering of the inside of the esophagus can be ulcerated through by having something sit there,” explains Tallant.
She adds that a dog with a foreign object stuck in its esophagus will often regurgitate food (bring food back up shortly after eating) — a common symptom of esophageal obstruction. But if owners mistakenly think their dog is vomiting, they may not take their dog to the veterinarian right away.
“Surgery is actually not the ideal option at all, but in bad cases that have been sitting there for a while, you have to do surgery because the esophagus isn’t intact.”
Right now, small animal surgeons have a choice of two surgical approaches to remove an obstruction from a dog’s esophagus. They can perform a median sternotomy (splitting of the breastbone) or they can enter the dog’s chest cavity through the space between a dog’s fourth and fifth rib (a thoracotomy).
But there are risks involved with existing surgeries — mainly because so many important vessels run alongside the esophagus.
“To do the procedure, you actually have to pull on those vessels that supply the brain,” says Tallant.
Preventing proper blood flow to the brain decreases the amount of oxygen flowing to the brain. This can lead to serious problems for the patient including neurological damage or even death in some cases.
Tallant and her supervisor, Dr. Kathleen Linn, are now investigating another approach that’s potentially safer. It involves entering the dog’s chest cavity through the space between the first two ribs (a first intercostal space thoracotomy).
“The idea of this new approach is to try not have to move or occlude any of those vessels,” explains Tallant.
The idea for Tallant’s research project, which is supported by the WCVM’s Companion Animal Health Fund, was actually developed after a patient died following a sternotomy.
This surgical option could reduce the amount of manipulation that vessels must undergo, improving the outcome of the surgery for the pet. It may also shorten recovery times, leading to less stress for the dog and less of an emotional and financial burden for the owners.
During her study, Tallant will examine computed tomography (CT) images to compare the location of anatomical structures within the chest cavity of different small breed dogs.
The two procedures — sternotomy and thoracotomy — will then be tested and compared on canine cadavers, all of which were euthanized for reasons unrelated to the study and donated to the WCVM. For each surgical approach, Tallant will measure the percentage of esophagus available with and without retraction of the important vessels.
Tallant says the new approach will likely be performed on the next patient requiring surgical esophageal foreign body removal since complications are no more likely than with the current procedure.
Fortunately severe esophageal blockages are rare, and Tallant has yet to have another patient requiring this type of surgery.
How can owners like me prevent their dogs from swallowing items that they shouldn’t? Tallant’s advice: make sure your dog’s balls, toys or chewing objects are all large enough so they can’t be quickly swallowed.
“But dogs will be dogs,” says Tallant.
As for my dog Maggie, pigs’ hooves are no longer on the menu. They’ve been replaced with more durable and safer chew toys that won’t lead to a potentially sticky problem.
Melissa Cavanagh of Winnipeg, Man., is a second-year veterinary student who is the WCVM’s research communications intern for the summer of 2013. Visit WCVM Today to read more WCVM news.