Part of the official UK Kennel Club testing scheme in Retriever (Golden)
Ichthyosis is a type of dermatitis (skin disease) caused by skin cells not working properly. This leads to large, different coloured scales on the skin. It is an inherited condition and has been found in many different breeds of dog, but they are not all caused by the same underlying genetic defect.
Ichthyosis in the Golden Retriever is recessive. Dermatological signs are visible from as young as a few weeks of age and include mild, moderate or severe scaling, initially with small white scales progressing to large blackish scales. There is no treatment for this disease, however, in some cases scale formation decreases in older dogs.
The insertion-deletion in the gene called PNPLA1 that causes Ichthyosis (PNPLA1 type) in Golden Retriever is autosomal recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop Ichthyosis during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop Ichthyosis as a result of the PNPLA1 mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop Ichthyosis should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the PNPLA1 mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Ichthyosis (PNPLA1 type), and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.