Firstly sneezing is a sign of nasal irritation and is a reflex action. Sneezing can be caused by (1) a minor nasal irritation or allergy (2) dust, pollens, cigarette smoke etc. (3) feline viral respiratory disease – the first signs of (4) foreign body in the nose (5) bacterial infection.
Prolonged sneezing can cause a nosebleed which is where you’ll see sneezing blood.
Feline nosebleeds can happen spontaneously. A blow to the face can cause one. The erosion of the nasal membrane can also be the cause. A tumor, parasite, infection and foreign body can cause this. Nosebleeds can also be cause by a blood clotting disorder because of exposure to a rodenticide.
Nosebleeds can cause sneezing, which makes the bleeding worse.
Needless to say a cat with a nosebleed should be taken to your veterinarian to diagnose the cause. The cat should be allowed to be quiet and calm and applying ice cubes to the bridge of the nose (if possible) will reduce blood flow and aid clotting.
Persistent nose bleeds need veterinary intervention.
A bloody discharge when the cat has a bacterial nasal infection indicates ulceration of the nasal membrane. The discharge will be creamy-yellow. The cat may have a fever.
The bottom line is that if and when your cat sneezes blood a veterinary visit is clearly indicated for diagnosis. If there is a foreign body in the nose and you can see it and it can removed with tweezers while taking great care, then that is one occasion where a DIY approach seems to be satisfactory. If a foreign body has been in the nose for 24 hours or longer it is likely that there will be a secondary bacterial infection and a purulent discharge.
The central issue is a proper diagnosis to know what is causing the nosebleed.
Source: The Nose in Cat Owner’s Home Veterinary Handbook.Home→Cat Health→sneezing→Is your cat sneezing blood? What could it be?