Hemophilia occurs as a result of genetic mutation, and once it develops, it can be transmitted to a cats offspring. Because female carriers are asymptomatic (meaning they dont show any symptoms), it can be challenging to identify them to avoid passing the hemophilia mutation onto the next generation.
Evaluation of pedigrees can determine carrier status of some asymptomatic females. It can also help estimate the risk that some animals are carriers, as well as help confirm laboratory diagnosis of affected males or females.
All daughters of hemophilic males will be carriers of hemophilia and should not be used for breeding. These females can be safely spayed and will not demonstrate signs of hemophilia. The full sisters and maternal half-sisters of hemophilic males have a 50 percent chance of being carriers of hemophilia, and Cornell recommends that these cats not be bred.
It is recommended that all sons of confirmed or possible carrier females be screened for hemophilia. Males confirmed to be clear of hemophilia can safely be used for breeding without further propagation of the defect.