The term brachycephalic comes from the Greek words brachy, meaning “short” and cephalic, meaning “head.” Brachycephalic dog breeds have flat faces with shortened muzzles. Unfortunately, the shortened muzzles and snouts often mean that the throat and breathing passages are also undersized or flattened. The term Brachycephalic Obstructive Airway Syndrome, or BOAS, refers to multiple anatomic abnormalities that can lead to breathing difficulties and other health problems for these dogs.
As many as six anatomic abnormalities make up BOAS. Not all dogs have all six abnormalities, but the more a dog has, the greater their clinical signs. The table below lists the medical names for the abnormalities followed by their definition.
Anatomic Abnormality
Definition
Stenotic nares
Nose holes are too narrow or collapse inward during inhalation
Extended nasopharyngeal turbinates
Air filtering bones inside the nose extend into the back of the throat
Elongated soft palate
Roof of the mouth is too long
Laryngeal collapse
Voice box collapses, making air passage difficult
Hypoplastic trachea
Windpipe is too narrow for the dog’s size
Everted laryngeal saccules
Pouches inside the voice box turn inside out and block airflow
All of these anatomic abnormalities lead to a decrease in air flow in and out of the lungs. The abnormalities associated with BOAS cause affected dogs to easily overheat because they cannot effectively cool themselves through panting. Stress, anesthesia, and exercise are also difficult for these dogs. Finally, dogs with BOAS often have lower blood oxygen levels as compared to non-brachycephalic breeds.
Patellar luxation is a common orthopedic condition in which the kneecap moves out of its normal position. It can affect one or both knees, and frequently occurs due to abnormalities of the bones or ligaments above and below the knee that affect how the knee is aligned in the joint. Occasionally, a luxating patella can occur due to trauma to the knee.
The kneecap may shift, or luxate, towards the inner thigh (medial) or towards the outer thigh (lateral). Cats and small breed dogs typically experience a medial luxation whereas larger breed dogs typically experience a lateral luxation.
A luxating patella is a common orthopedic condition in which the kneecap moves out of its normal position. It can affect one or both knees, and frequently occurs due to abnormalities of the bones or ligaments above and below the knee that affect how the knee is aligned in the joint. Occasionally, a luxating patella can occur due to trauma to the knee.
The kneecap may shift, or luxate, towards the inner thigh (medial) or towards the outer thigh (lateral). Cats and small breed dogs typically experience a medial luxation whereas larger breed dogs typically experience a lateral luxation.
Hip dysplasia is a skeletal disorder that results in instability or looseness of a dog’s hip joint. The hip joint normally functions as a ball and socket but, in dogs with hip dysplasia, the ball and socket do not fit properly — instead of rolling and sliding, they rub and grind.
Since the bones of the joint don’t line up correctly, the joint cartilage is subjected to abnormal wear and tear. Over time, cartilage damage occurs, resulting in pain and arthritis.
The cranial cruciate ligament (CCL) in dogs is the equivalent of the anterior cruciate ligament (ACL) in humans. It is one of the ligaments that connects the thighbone (femur) to the shinbone (tibia) where they meet at the knee (known as the stifle joint in dogs) and help keep the joint stable. When the cranial cruciate ligament ruptures, the knee joint destabilizes, twists, and slips. If the ligament is partially torn, your dog may just limp, but once the ligament completely ruptures, your dog may refuse to put weight on the limb and walk on three legs. Movement of the misaligned joint causes further damage, inflammation, pain, and eventually arthritis.
In humans, injury to the ACL usually occurs during sports that involve sudden stops or changes in direction, such as football or skiing. In dogs, the cranial cruciate ligament tends to degenerate over time until the ligament weakens and ruptures. Since the disease process is degenerative, both the right and left cranial cruciate ligaments are often affected. About half of dogs who rupture one CCL eventually will rupture the second.
