(Hereford cattle)

Syn: Haemophilia A.

A sex-linked inherited defect that usually presents as a fatal hemorrhage event following castration. In one herd when a 'bleeder' bull was used over heterozygous cows, some daughters were observed to bleed excessively when ear marked. It would be reasonable to expect dehorning and parturition may also present life-threatening challenges to homozygous heifers. Dehorning would also present a life-threatening challenge to bulls that inherited the mutation from their clinically normal heterozygous dam.

The condition has been recorded in Hereford cattle in Australia, but may arise in any breed due to new mutations.

Diagnosis

A history of severe haemorrhages in grandsons of a sire should raise a suspicion of haemophilia A.