TL;DR: Dark, gritty ear discharge in cats usually indicates ear mites or an infection; schedule a vet visit within 48 to 72 hours and avoid home remedies until the eardrum is checked.
What causes coffee ground-like discharge in my cat's ears?
If you notice a dark, crumbly, or gritty substance inside your cat's ears that looks like coffee grounds, it is frequently a sign of an ear mite infestation (Otodectes cynotis). This debris is composed of earwax, inflammatory fluids, and the waste products of the mites. In some cases, a similar appearance can be caused by a chronic yeast or bacterial infection, which leads to the buildup of dark wax.
Is coffee ground ear discharge a veterinary emergency?
- The urgency level for coffee ground discharge is low; while uncomfortable and irritating, it is not a life-threatening emergency.
- Schedule a veterinary appointment within the next 48 to 72 hours.
- Avoid using over-the-counter treatments until a vet confirms the eardrum is intact, as some medications can be toxic if the drum is ruptured.
How does sending a photo help my veterinarian triage my cat?
- A clear, close-up photo allows the triage team to see the volume of debris and the level of redness or swelling in the ear flap.
- Visuals help the staff determine if your cat needs to be squeezed in sooner or if a standard appointment is appropriate.
- Photos provide a vital baseline to track the effectiveness of treatment later on.
Clinical Context (Merck Veterinary Manual)
In cats presenting with ear discharge, especially a coffee-ground appearance, ear mites (Otodectes cynotis) should be a primary differential for otitis externa. Diagnosis involves clinical signs, history, and ear swab cytology to identify mites. Feline demodicoses can also manifest as pruritic otitis, so skin cytology from the pinnae and exudates is warranted. Notoedres cati infestation should be considered, characterized by severe pruritus, crusts, and alopecia, particularly on the ears, head, and neck, with mites readily found on skin scrapings. Selamectin (6 mg/kg, spot-on), moxidectin (1 mg/kg, spot-on), ivermectin (200 mcg/kg, SC), or lime sulfur dips can be used for treatment.
Chapter: Dermatology, Infectious Diseases
Source: The Merck Veterinary Manual, 11th Edition (Page 528)