Ichthyosis (American bulldog type) is an inherited condition of the skin affecting dogs. Affected dogs present as early as 1-2 weeks of age with flaky skin and a scruffy haircoat when compared to normal littermates. Typically before 6 weeks of age the skin of the abdomen is reddened, wrinkled, and covered by light brown scales. As the dog ages the sparsely haired areas of the dog become red-brown with adhered brown scales and large white to tan scales are found throughout the haircoat. Dogs may also have thickened footpads. Affected dogs are at increased risk for infections of the skin, ears, and footpads and may require treatment for these infections throughout their lives.
Genetic testing of the NIPAL4 gene will reliably determine whether a dog is a genetic Carrier of ichthyosis (American bulldog type). Ichthyosis (American bulldog type) is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the NIPAL4 gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Dogs that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
Briand A , Cochet-Faivre N, Reyes-Gomez E, Jaraud-Darnault A, Tiret L, Chevallier L. NIPAL4 deletion identified in an American Bully with autosomal recessive congenital ichthyosis and response to topical therapy. Vet Med Sci. 2019 May;5(2):112-117. doi: 10.1002/vms3.149.
Casal ML, Wang P, Mauldin EA, Lin G, Henthorn PS. A Defect in NIPAL4 Is Associated with Autosomal Recessive Congenital Ichthyosis in American Bulldogs. PLoS One. 2017 Jan 25;12(1).
Mauldin EA, Wang P, Evans E, Cantner CA, Ferracone JD, Credille KM, Casal ML. Autosomal Recessive Congenital Ichthyosis in American Bulldogs Is Associated With NIPAL4 (ICHTHYIN) Deficiency. Vet Pathol. 2015 Jul;52(4):654-62.
Mauldin EA. Canine ichthyosis and related disorders of cornification. Vet ClinNorth Am Small Anim Pract. 2013 Jan;43(1):89-97.