Haemophilia 'A'


Haemophilia 'A' is a condition where the blood fails to clot normally, due to a deficiency of Factor VIII. Though the disease has long been known in man, it was described in dogs about 50 years ago. Most breeds are affected to some degree, but we will concentrate on the GSD.
The symptoms depend on the severity of the disease, and vary from lameness, swellings and 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. It is thought that the more severely affected animals die early or are still born, so most cases surviving to maturity are only mildly affected and are not so easily detected.
There are blood tests that can be done to detect haemophiliacs, but because of the nature of the inheritance of the disease, only the males can be declared clear. It is inherited as a sex-linked recessive gene, which means it is carried on the 'x' chromosome. The female has two of these, whereas the male has an 'x' and a 'y'. This is where the problem in detection arises, as the male is either affected or clear, depending on whether his 'x' chromosome carries the defective gene or not, but the female has two 'x's, so three states exist. These are 'clear', where neither chromosome carries the fault, 'carrier', where one 'x' has the fault, but is hidden by the other normal 'x', and 'affected', where both 'x's have the faulty gene. This is why the females are not tested, because it can only show up whether she is affected or seemingly clear, when she may actually be a carrier.
In theory, there are six possible types of matings.

As can be seen from the table, a clear male mated to a clear female will produce all clear progeny (barring any mutations). A clear male mated to a carrier female will be expected to produce clear and affected sons, and clear or carrier daughters. This is the most common way that haemophiliacs are produced, as no-one knowingly uses affected males or females. If a male is only mildly affected, and hasn't been tested clear, he may appear to be OK, but as can be seen from examples 3 and 4, the problem can still be passed on to his offspring.
The main source of haemophilia in the GSD seems to be from Canto Von Der Wienerau, with his sons all being clear, and his daughters all being carriers (mating no. 3). 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, and the book, 'The German Shepherd Dog A Genetic History of the Breed' by Malcolm Willis (used as reference for this section) gives a list of dogs implicated as affected or producers of the disease, as well as giving more in depth information about it.
The blood test for the disease is inexpensive, and a list of dogs that are tested clear is available from the National G.S.D. Breed Council (see 'Useful Links' page)