TL;DR: If your cat is scratching their ears until they bleed, it is likely due to mites or an infection and requires a veterinary visit within 24 to 48 hours to prevent further injury.
What causes my cat to scratch their ears until they bleed?
- Pruritus: Intense itching that leads to self-inflicted bleeding.
- Ear mites: Microscopic parasites that are the most common cause of extreme irritation.
- Infections and allergies: Triggers include bacterial or yeast infections, flea allergies, or environmental allergens like pollen and dust.
- Fragile skin: The thin skin on the ear flap is easily damaged by a cat's sharp claws.
Is it an emergency if my cat is scratching their ears?
- Urgency Level: This condition is considered Medium priority.
- Patient distress: While rarely life-threatening, it indicates significant pain and distress.
- Potential complications: Untreated scratching can lead to aural hematomas (blood-filled swelling) or severe secondary infections.
- Timeline: Aim to see a veterinarian within 24 to 48 hours for treatment and pain relief.
How can a photo of my cat's ears help with triage?
- Identifying discharge: High-quality photos help vets distinguish between dark, crumbly mite debris and yellow pus from infections.
- Assessing trauma: Images show the extent of skin damage to determine how quickly your pet needs to be seen.
- Clinical preparation: Photos help determine if a specialized ear exam is required before you arrive.
Clinical Context (Merck Veterinary Manual)
In cats, continual ear scratching leading to bleeding is commonly associated with ear mites, particularly those of the family Psoroptidae, which cause otitis externa. Notoedres cati, a mange mite, can also cause severe pruritus, leading to papular eruptions, scaling, crusting, excoriations of the ear margins, and subsequent scratching. Auricular hematomas, fluid-filled swellings on the concave surface of the pinna, can develop secondary to head shaking or ear scratching due to pruritus. Diagnosis of mite infestations is based on clinical signs, history, and skin scrapings, although negative scrapings do not exclude the diagnosis. In severe cases, oral short-acting glucocorticoids may be necessary to reduce inflammation and pruritus.
Chapter: Dermatology, Parasitology
Source: The Merck Veterinary Manual, 11th Edition (Page 921)