One genetic issue that is not commonly seen in recent times is endo- or ecto- tropian (where eyelashes curl up or down into the eyelid). Crossed eyes, splayed feet, weak pasterns, improper rear angulation and cow-hocked dogs can pass on those traits to offspring, but these are not life threatening -- just not preferred for breeding as their conformation is flawed.
Another less commonly seen, but serious genetic disorder is called Canine Neuronal Ceroid Lipofiscuionis, or "NCL." Many breeders, as well as many vets, are not even familiar with this disorder, but is a very serious one that does not generally show up until the dog is about 2 years of age. The disorder will start by the dog appearing to lose control of his hindquarters, falling over, and eventually unable to move at all. There is no cure and death is inevitable. There is a test for this genetic marker available commercially, and responsible breeders will test their breeding stock, and if they choose to breed a carrier will test the offspring and provide full disclosure to the puppy purchaser, particularly if the puppy is being sold as a breeding prospect. More information concerning NCL can be seen here:
The pups in these pictures were produced at Eagle's Wing Kennels before any commercial genetic testing was available. The University of Pennsylvania was working on isolating the gene, and with help of biopsies from these 2 puppies they were able to complete their research and finish developing the test that is commercially available today. Both of these puppies ended up having very moderate cases and were homed with owners that were willing to deal with their special needs. One of them, Moose, is shown as an adult in the slideshow.
American Bulldogs have been known to have a myriad of health issues that are common in the breed, some of which were inherited from the breeds used to re-develop the American Bulldog in the last 30 years. Some genetic issues include the usual suspects for large breed dogs, such as elbow and hip dysplasia. That is why it is important that breeders utilize all available resources when selecting which dogs are bred together. Genetics is a curious thing. There are multiple genes that make up any animal, and some particular traits, i.e., eye color, are made up of several genes together. Dysplasia can occur in dogs even if their parents are both OFA Excellent -- but the chances of producing a dysplastic animal from a line of dogs that have produced good hips, etc. are greatly decreased. To a certain extent, temperament also is genetically predisposed. For these reasons, it is good to know the history of as many dogs in a pedigree, including those produced by those dogs and their progeny, if possible. Reputable or conscientious breeders will communicate with other breeders and cooperate with sharing knowledge with each other in order to work toward improving the breed.
American Bulldogs can have allergies. Allergies are caused by an overactive immune system. This can be caused genetically, or may also be imposed by over vaccinating an animal. Sometimes young dogs will present with allergic symptoms as their immune system develops, and too many vaccinations (many of which are unnecessary) an exacerbate an already delicate balance. Sometimes these young dogs grow out of the allergies. Severely allergic dogs may remain so for their entire life, but most can be managed. Dogs or lines of dogs that have allergies or produce pups that exhibit allergic tendencies should not be included in a breeding program.
There are two diseases that can affect the American Bulldog for which genetic testing is available. By testing breeding individuals, a breeder will know whether the breeding pair are likely to produce affected pups, or whether the pups will be clear.
One such disease is known as Icthyosis, which is a skin disorder that is readily apparent in newborn puppies, if affected. See pictures of examples below. Icthyosis can range from moderate to severe, but is not life threatening. In moderate cases, the dog will have some flakey skin and may require more bathing and oiling to maintain comfort. Severe cases means a dog that will be quite itchy and will require daily oiling and frequent bathing to keep him comfortable. The good news is that testing is available that will identify whether a puppy is free of the Icthyosis gene, or a carrier. A puppy that is a carrier will NOT be affected by the disease, but is capable of producing affected individuals if bred to another carrier. A puppy that is clear of the gene cannot produce affected offspring. Affected individuals will always produce carriers, even if bred to a clear, because they carry the two alleles that are required to produce the affected dog.