Hemophilia A (boxer type) is an inherited bleeding disorder affecting dogs. Hemophilia A (boxer type) is caused by a deficiency of coagulation factor VIII, which is an essential protein needed for normal blood clotting. Affected dogs may bruise easily, have frequent nosebleeds, bleed from the mouth when juvenile teeth are lost, and experience prolonged bleeding after surgery or trauma. Dogs may show signs of lameness or stiffness if bleeding occurs in the joints or muscle. Less often, the bleeding may be severe enough to cause death. Due to the variable severity of the disorder, affected dogs may not be identified until a surgery is performed or trauma occurs at which time excessive bleeding is noted. Veterinarians performing surgery on known affected dogs should have ready access to blood banked for transfusions.
Genetic testing of the F8 gene will reliably determine whether a dog is a genetic Carrier of hemophilia A (boxer type). Hemophilia A (boxer type) is inherited in an X-linked manner in dogs meaning that female dogs must receive two copies of the mutated gene (one from each parent) to develop the disease while male dogs only require one copy of the mutated gene from the mother in order to develop disease. Therefore, male dogs more commonly present with symptoms of the disease. Each male pup that is born to a female dog known to be a carrier of hemophilia A (boxer type) has a 50% chance of inheriting the disease. Reliable genetic testing is important for determining breeding practices Because symptoms may be mild in affected dogs and female carriers generally do not have features of the disease, genetic testing should be performed before breeding. In order to eliminate this Mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers 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.
Christopherson PW, Bacek LM, King KB, Boudreaux MK. Two novel missense mutations associated with hemophilia A in a family of Boxers, and a German Shepherd dog. Vet Clin Pathol. 2014 Sep;43(3):312-6. doi: 10.1111/vcp.12172.