Haemophilia A
Haemophilia 'A' is a condition where the blood fails to clot normally, due to a deficiency of Factor VIII. The disease has long been known in man, but has only been known in dogs for the last 50 years or so.
The symptoms depend on the severity of the disease, and varies from severe haemorrhage at the slightest injury due to failure of the blood to clot in the normal time, to nothing visibly obvious in mildly affected dogs. Severely affected dogs may bleed spontaneously into body cavities, muscles or joints, so causing the swellings or lameness, whereas the mildly affected ones may only become apparent after surgery or injury, when the bleeding is difficult to stop.
The most severely affected animals will die early, so most cases which survive to maturity are only mildly affected and are not so easily detected.
As in humans, it is only the male that is affected by the disease. In theory a female could be affected if an affected male was mated to a carrier female, but this would be an extremely rare occurance.
Blood tests can be done to detect haemophilia, meaning that males can then be certified clear of the disease.
However, due to the mode of inheritance of the disease, only the males can be declared clear. It is inherited as a sex-linked recessive gene.
A male affected with haemophilia will produce sons who are clear of the disease and daughters who will not be affected, but will all be carriers.
These daughters will then produce males affected by the disease. It is not possible, however to test for carrier status, therefore females are not tested. It is therefore important that all males are tested clear before being used for breeding, so that they cannot pass the gene to their daughters.
A male cannot carry the disease, he is either affected or clear.
The main source of haemophilia in the GSD seems to come from the famous dog Canto Von Der Wienerau, with his sons all being clear, and his daughters all being carriers. Although not tested, he died young in circumstances that would suggest that he was a haemophiliac. Although his sire was clear, the status of his mother was not known. All recent cases of the disease have been traced back to Canto through his daughters.
All reputable breeders have been testing their stud dogs for haemophilia for the last 20 years, so thankfully the disease is now very rare.
