If you're fond of dogs that have a "smashed in" face, then your pet likely falls into a special category of canine known as brachycephalic. The term comes from two Greek words: "brachy," which means short, and "cephalic," which means head.

These types of dogs have been bred through the generations to have a normal lower jaw in proportion to their body, and a compressed, or shorter, upper jaw. Because of selective breeding, these dogs also have developed a number of health conditions that may cause concerns.

Specifically, these dogs often have brachycephalic respiratory syndrome, a condition that affects different areas of the respiratory tract. Breeds most often affected are Boston Terriers, Bulldogs, Pekingese, Pugs and Shih Tzus.

Some brachycephalic dogs have stenotic nares, which is a medical term for extremely narrowed nostrils that interfere with breathing. In the most severe cases, these nasal openings can be widened with surgery. These dogs also can have tracheal stenosis, a condition in which portions of the animal's windpipe are extremely narrow. This causes a number of problems for the affected animals, plus it places them at very high risk if they undergo anesthesia. Because of this, your veterinarians will perform X-rays prior to any surgery if your dog is a brachycephalic breed, and then make adjustments as needed.

Finally, because of their shortened face, the soft tissues inside the dog's mouth and throat do not fit properly. The soft palate, which is responsible for separating the dog's nasal passages from the mouth, is too big, and the ends of it hang down loosely inside the dog's throat. This causes the snorting sounds that are familiar to owners of affected breeds, and in Bulldogs it can occasionally cause difficulty breathing. In all brachycephalic dogs, a period of intense barking or panting can cause their throat to swell, again interfering with breathing.

Normal dogs cool themselves by panting, passing air quickly over the throat and tongue. Saliva evaporates from the tongue and cools the blood that is circulating through the tongue. This cooled blood then circulates through the dog's body, reducing its temperature. The physiological limitations of brachycephalic dogs make them unable to pass air quickly through their throats and mouths. Because they are inefficient panters, they also are unable to cool their body very efficiently, and thus are more susceptible to heat stroke and other heat-related illnesses. Plus, the extra work required in order to pant can cause the dog's airways to become swollen and inflamed, further exacerbating the problem.

Because of their shorter upper jaw, these dogs also are susceptible to problems with their teeth, which are crowded in the mouth and may grow at odd angles, trapping food debris and leading to gum disease. Infections in the skin folds of these animals also are common, and responsible owners should check their dog's skin regularly for any reddening. Also, eye problems may develop, since the eye sockets of these animals are very shallow, and even a minor accident can cause the eye to pop out of its socket. Or, the eyelids may not be able to fully close over the eyes, and there are several irritating eyelid conditions that can occur as well.

In most cases these problems are not severe, or can be treated with corrective surgery. Owners of a brachycephalic dog should, above all, take care to keep their pet cool during warmer months and to not let it become overweight. If you have any specific concerns about your dog, be sure to discuss them with your veterinarian.