Ichthyosis is a genetic skin disorder that appears in many dog breeds, but also is known in humans. In dogs, the disease usually does not kill affected individuals, but it makes their life and the lifes of their owners very uncomfortable.
Within the first two weeks after birth, signs of the disorder are recognizable in the affected puppies. Their skin is wrinkely and flaky. The pups appear dirty although their unaffected littermates are nice and clean. Already, in this stage, they smell different. In most cases it get worse the older the dog gets but there are also cases known were it receeds.
The dog will never recover, and weekly, if not daily, bathing and application of oils to the skin are required to keep the dog comfortable and to protect the skin from following infections. The skin may be very itchy. This can lead to scratching and chewing that will injure the skin further and can be prone to "hot spots".
Most informed breeders will cull affected puppies as soon as the sign are noticable. Others may not recognize the problem and sell affected puppies to unwary buyers.
Even most vets are not aware of Ichthyosis and will treat for bacterial- or fungus-infections. The signs will get better under the treatment but as soon as it stops, the condition will get as bad as it was before. Bathings and antibiotics keep secondary infections under control and take the flakes away, but the effect does not last longer than the treatment.
The existing test for Ichthyosis via skin-biopsy is not reliable at all.
Ichthyosis follows a dominant-recessive inheritance.
There are three possible genotypes which are:
Ichthyosis clear (0/0), this means the individual has two intact genes and can only pass those onto any offspring. There will never be any offspring affected if it has one parent that is Ichthyosis clear.
Ichthyosis carrier (0/+), this means the individual has one intakt gene and one defect gene. The individual is unaffected and healthy. It will pass statistically an intact gene onto 50% of its offspring and a defect gene to the other 50%.
Ichthyosis affected (+/+), this means that the individual only has two decet genes. This is why it is affected and canl only pass defect genes onto its offspring.
By breeding two Ichthyosis clear dogs together they will only produce Ichthyosis clear offspring. Breeding a carrier to a clear dog will result in 50% clear offspring and 50% carrier offspring.
As carriers are healthy and show no signs of the disorder, they cannot be recognized by their looks, and breedings between two carriers can be done. In this case 25% of the offspring will be affected, 50% will be carriers and 25% will be clear.
Up to now, only through randomly made breedings between two carriers and their affected offspring, carriers could be identified.
Since august 2011 there exists a gene-test for Ichthyosis in American Bulldogs. This allows to identify every american bulldog's genotype before breeding and it becomes easy to avoid the birth of affected animals by avoiding breedings of two carriers to each other.
Every breeder should now test his/her complete breeding stock before planning any further breedings to avoid the birth of affected pups.
If a carrier is bred to a clear partner the whole litter should be tested prior to leaving the breeder to show transparence and to be able to tell the buyer about their puppy's Ichthyosis-status.
The test is breed-specific and up to now is only available in Pennsylvania, USA, but test-material can easily be sent over and the result is available in approximately 4 weeks.