Perhaps one of the most difficult aspects of breeding for a particular look in a type of dog is that often the altering of the physical attributes of the dogs over time results in significant problems for future generations. This is perhaps most obvious with the inherited respiratory conditions which tend to be most pronounced in breeds that have been selective bred for short muzzles and pushed in faces. It is important to note that not all respiratory problems that can be inherited are solely caused by specific types of breeding programs. There are specific conditions that can occur within lines and breeds of dogs however these conditions are often not life threatening unless there are other complicating factors.
The most common type of inherited breathing disorder is called Brachycephalic Airway Obstruction Syndrome or BAOS. Since it is caused by breeding progressively shorter and shorter muzzles on specific breeds of dogs, many owners and breeders don't realize it is actually a medical condition, rather they assume it is a breed trait. Any and all of the very short nosed dogs can have this type of congenital or from birth respiratory problem. These include Pugs, English Bulldogs, Cavalier King Charles Spaniels, Shar-Peis, Boston Terriers, Pekingese, French Bulldogs and the Shih Tzu breed.
BAOS has a wide spectrum of symptoms, many which are not a problem for the dog or the owners, providing there are no other health problems. Generally most dogs will have problems with snuffling and snorting during exercise and perhaps some problems with snoring and wheezing noises during sleep. When these dogs, even with mild symptoms, have another respiratory problem this increased breathing difficulty can cause significant problems. Dogs that are obese or highly inactive and have BAOS may also have problems with fainting, rapid and shallow breathing, accelerated heart rates and possibly collapsing during exercise. Heat stroke will be very common in these dogs and they have to be carefully monitored when exercising even at moderate levels in the hot or humid conditions.
More commonly seen in the heavier, larger English Bulldogs is also a type of sleep apnea that can occur. This disorder can put additional strain on the heart and may lead to increased stress and anxiety for the dog. The difficulty breathing can also bring on stress and anxiety, which causes the dog's body to respond by panting harder and faster. This vicious cycle can lead to vomiting and gagging, possibly even causing material from the trachea to get into the lungs, which can occur because of the short space between the two. When this happens there is greater chance of pneumonia and other respiratory infections developing, especially in younger dogs and puppies.
In cases where the deformity to the respiratory system is significant there are some surgical procedures that can remove excess tissue and restructure the airways. This is typically only done on young dogs, with corticosteriods and other anti-inflammatories used in conjunction with oxygen therapy for those dogs that only have occasional bouts with the problem breathing.
Generally most breeders understand that while short muzzles in these breeds are desirable, when they cause health problems they are a real drawback. Reputable breeders do not use dogs with significant BAOS in breeding programs and avoid any combinations of lines that are known to have these structural problems.
Another inherited respiratory problem in some breeds of dogs is known as laryngeal paralysis. This condition is not a result of a specific breeding practice, but rather is related to a nervous disorder. The nerves that control the muscles of the larynx don't work properly, so the larynx doesn't open fully when the dog inhales. The result is a labored inward breath, often sounding like a very harsh breathing or a loud almost roaring type sound. These dogs may cough frequently and collapse when exercising, especially in the heat. They often gag and vomit when eating since they have difficulty in coordinating their breathing and swallowing.
The breeds that are most commonly associated with laryngeal paralysis are large breeds. It is most often seen in the Dalmatian, Bouvier des Flanders, Bull Terrier and the Siberian Husky. Other large breeds may also have this condition, as can mixed breeds with these lines. In the Dalmatian this condition is often the first sign of a central nervous system disorder that affects more than just the breathing.
A vet can diagnose this condition rather easily as it typically occurs before 6 months of age and has very typical symptoms. The vet can also insert an optical tube into the throat and look directly at the larynx to determine if it is functioning properly. Once diagnosed if the condition is relatively mild the vet can teach the owner calming techniques and provide emergency sedatives to calm the dog and allow normal breathing to be restored. Often corticosteriods are prescribed as needed to help fight the swelling and irritation that occurs after difficult breathing. Keeping the dog out of hot and humid temperatures and keeping exercise to a mild to moderate level can help prevent any further episodes.
For some dogs with significant problems there are surgical options to enlarge the larynx, however this is not always appropriate for all dogs. Dalmatians that have laryngeal paralysis as part of the larger nervous system disorder will typically not become better after surgery and the condition will gradually become more problematic over time.
Since there are various genetic factors within breeds that are prone to this condition it is absolutely essential to avoid breeding any dogs that have a history of laryngeal paralysis, even if it is mild or manageable. In most breeds it is not recommended to use any siblings of an affected puppy in any breeding programs as they are likely to be carriers of the genetic condition.
Overall the inherited respiratory conditions in dogs tend to be rather rare, unless you are considering a brachycephalic breed. Always ask to see the mother and father dog and check for any signs of breathing problems with the dam and sire as well as with at least two generations back on either side. This should be far enough back to determine if there is any history of significant respiratory problems within the pedigree of your puppy.