Causes of cat ear bleeding:

1. Trauma. Cats are naturally more lively and active. During the process of jumping and running, they are likely to cause damage to the skin of the ear canal or rupture of blood vessels, resulting in ear bleeding.

2. Infection with ear mites. When a cat is infected with ear mites, the ear mites crawl in the ear canal, causing itching in the cat's ear canal, causing the cat to scratch frequently, leading to ear ulceration and ear bleeding.

3. Fungal or bacterial infection. Fungal or bacterial infection can cause inflammation of the skin in the cat's ear canal, leading to redness, swelling, ulceration, etc. in the cat's ear canal, which can cause bleeding in the cat's ear.

4. Secondary otitis media. Ear mites, bacteria, and fungal infections may also cause secondary otitis media in cats. Cats with otitis media will often scratch their ears due to strong itching, resulting in ear abrasions and bleeding.

5. Tumor. If a cat has a tumor in its ear, the tumor may rupture and cause blood vessels to rupture and cause bleeding.