Causes
Genetic diseases affecting the clotting factors (haemophilia and others). Some breeds have a known predisposition.
Diagnosis
Specific clotting tests. It is worth carrying these out before any surgery in at-risk breeds.
Treatment
There is no cure. It is managed by: avoiding drugs that affect clotting, planning surgeries with precautions, and treating bleeds (sometimes with a transfusion).
Prevention
Testing before breeding in predisposed breeds. Knowing the animal's status before operating.

