Hello XXXXXXXX
Bleeding of any sort is a serious problem. I can be from intoxication by warfarin like rodent poisons, clotting defects like hemophilia, or von Wilebrands disease or autoimmune disease like idiopathic thrombocytopenia.
If your cat has low clotting factors, is anemic or has low thrombocytes(platelets) transfusions may be needed to keep him stable until therapy can correct the problem.
http://www.VeterinaryPartner.com/Content.plx?P=A&A=1646
http://www.VeterinaryPartner.com/Content.plx?P=A&A=1765
http://www.VeterinaryPartner.com/Content.plx?P=A&A=2595
Hope this is helpful
Dr Dan
Cat Veterinarian
DVM, Practice owner since 1988, Memeber AAFP,AAHA, AVMA