I knew spring had arrived when one of my favorite patients, Rascal, a young bulldog, greeted me with an open-mouth smile, panting uncontrollably.
Rascal is usually panting, but with increased temperatures and humidity, he now must fully open his mouth just to be comfortable while resting. Brachycephalic dogs are the cute, personable breeds such as Bulldogs, Pugs, Pekingese and Boston Terriers. Their short noses and flat faces are an extreme disadvantage in hotter temperatures because the dog’s primary mechanism for beating the heat is panting, and these dogs do not pant efficiently.
Brachycephalic Airway Syndrome
Panting is a form of evaporative cooling, and air must easily flow for the process to work. The shorter faces of brachycephalic dogs make them look adorable, but they create big problems for airflow. These dogs suffer from brachycephalic airway syndrome (BAS), which causes inefficient breathing and, therefore, inefficient cooling.
BAS typically has several components. First, brachycephalic dogs have small nares, or outer nasal openings. Next, the inside of a dog’s nose is made up of layers of thin bone called conchae. Short-nosed dogs have the same amount of boney conchae as their long-nosed counterparts. However, the bones are more compact. This tight labyrinth of bone creates resistance for air movement and leaves the mouth as the main portal.
The mouth could do all the work, except brachycephalic dogs have long, soft palates in the back of their mouths. The palate tissue blocks the flow of air to the trachea. And lastly, many have small, hypoplastic tracheas in which the diameter of the trachea is greatly reduced.
Each of these structural problems interferes with how quickly air can pass to the lungs. Air movement for a brachycephalic dog might be the equivalent of a person who is trying to breathe with swollen tonsils and a clothespin on his nose.
Risk of Heat Exhaustion and Heat Stroke in Flat-faced Dogs
If evaporation is the way a system cools, and little air is passing through, the system quickly overheats. Dogs can easily suffer from heat exposure, but brachycephalic dogs have the highest risk for heat exhaustion and heat stroke.
Owners of brachycephalic dogs can help their dogs breathe easier and stay cooler through elective surgery. Nares can be made wider, the soft palate can be shortened, and new techniques in nasal surgery allow the boney conchae inside the nose to be greatly reduced, allowing for a tremendous increase in air movement.
If surgery is not an option for your dog, then take all precautions. Remember that when it comes to keeping cool, dogs are at the mercy of their environment. Take these steps:
Protect your flat-faced dog from the heat. Provide plenty of shade, air-conditioning, and a cool pool of water to help your dog escape the heat.
Provide plenty of water. A supply of cold drinking water should always be available.
Exercise your flat-faced dog with caution. Walk or exercise only in the early morning or late evening, when the temperatures are cool.
Monitor your dog’s health. Pay close attention to your dog’s respiratory rate, effort to breathe, stamina, willingness to continue and fatigue. All can be signs of possible overheating.
Respond quickly. If your dog is working hard to breathe, and if his tongue is flat and wide for maximum evaporation, don’t ignore it. Take immediate measures to cool him down.
Control your dog’s weight. Maintaining a healthy weight can help brachycephalic dogs breathe easier.
By Dr. Tracy Dewhirst