Dealing With Feline Ear Infections

What IS That Gunk and Funk?

Teresa Keiger

You are having a grooming session with your favorite feline companion: a mani/pedi, a comb out to remove any knots, and finally, a wipe of the ears. But this time, you notice that the ear is full of black gunk! Eww…something smells a bit off! What is it and how did it get there? More importantly: what should you do?

Anatomy of the Feline Ear

Feline (and canine) ears are shaped markedly different from human ears. They are divided into three sections: the outer ear, the middle ear, and the inner ear. The outer ear begins with the external ear itself (the pinna). The vertical ear canal begins here and extends straight down and then makes a 90o turn to the interior, becoming the horizontal canal which then proceeds on the middle ear. An infection in the outer ear is called otitis externa.1

A Balanced System

Most cats’ ears are clean and shiny. Just like human ears, feline ears are self-cleaning. A process called epithelial migration starts at the tympanic membrane (between the middle and external ear). Epithelial cells are a type of cell that forms the lining of surfaces throughout the body, including the skin, blood vessels, and organs like the intestines and kidneys.2 These epithelial cells divide, and begin to migrate outwards through the ear canal, carrying with it debris, cerumen (wax), and any other trapped material. This mixture slowly migrates to the canal in the outer ear where it is dispersed. If something enters the ear canal (like stray hairs), the ear will produce more wax to push it out of the canal.3

The ear canal also contains a host of other things. The ear is also normally colonized by a variety of organisms including Staphylococcus spp., Streptococcus spp., Corynebacterium and Malassezia spp., as well as yeast. These organisms live in harmony within a normal ear canal—unless something disrupts their balance. While cats can and do have bacterial and/or yeast infections in the outer ear, that infection is a result of something else causing an opportunistic yeast/bacteria secondary infection.4

Many things can cause a disruption in this balance. We’ve already mentioned stray hairs in the ear canal, but excess hair around the ear can also cause excessive wax production. Water in the ear (usually from bathing) can become trapped, resulting in an infection. Sometimes cats can develop a polyp in the ear and these growths can often lead to infections.6 (note that there is no real “cure” for ear polyps except for surgical removal, and even then there exists the possibility of recurrence.)

One prime cause of ear infection are ear mites (Otodectes cynotis).5 More often found in outdoor cats, ear mites spread directly from cat to cat (or dog to cat). They burrow into the ear canal and cause irritation and inflammation. You will probably notice your cat scratching their ear and shaking their head. There may be thick dark debris in the ear that looks like coffee grounds. This is the dried blood from the ear mites munching on the epithelial cells. The irritation that mites cause can also lead to a secondary bacterial or yeast infection.

Allergies are another prime cause of ear infections via flora/fauna imbalance. Food and environmental allergies can cause itchiness and inflammation in the areas around the ear canals. The ear canal may narrow because of the surrounding inflammation.  The epithelial cells produce more cerumen trying to push out the perceived irritant causing what we see as a yucky discharge. This allergic reaction may also trigger an imbalance of the natural flora and fauna, leading to bacterial or yeast infections of the ear. An overgrowth of yeast will have that particular “funky” smell.

Treatment

Ear mites appear as dark specks which look like coffee grounds.

If you suspect that your cat is having an issue with his ears, do seek veterinary help as you will need the proper medicines to address your cat’s medical situation. And it may be that your cat has both a primary and secondary infection.

Ear mites requires your veterinarian to completely clean out the ears to remove the debris and then treating the mites with a topical solution, such as Revolution, on the back of the neck.5 In some cases, the amount of debris and infestation is so significant that your veterinarian may have to sedate your cat to deeply clear the ear canal. If you have additional animals in your household, do check their ears for mites as well, as they will continue to reinfect each other. Ear mites do take about a month to fully eradicate, so do keep the affected cat away from any other pets.

Secondary bacterial or yeast infections need medications to eradicate them too: antibiotics for bacterial infections, antifungals for yeast infections.  Your veterinarian may also prescribe prednisolone (a steroid) for severe inflammation. These medications may be in oral or topical form. DO finish the entire course of treatment or your cat may become ill again.

Prevention

Yeast infections have a formless dark discharge with a distinctive smell.

Maintaining healthy ears goes a long way in preventing ear infections. If your household has other pets that go outside, then flea and tick prevention for ALL pets is essential.5 Ear mites (and other parasites) are easily exchanged when pets play or sleep with each other.

Remember that food or environmental allergies can also affect a cat’s ears. Be cognizant of this and address the root cause of the allergies.

Clean your cat’s ears only under the instruction of your veterinarian. Otherwise, you may do more harm than good. Any cleaning that you do should be a wipe down of the outer ear only with an appropriate ear cleaner and cotton ball. While you might be tempted to dig around the ear canal with a cotton squab, don’t. This can push debris further down into the canal and/or irritate the canal.

In Conclusion

Cats’ ears are normally clean and shiny, so a change in appearance is a good indicator that something else is going wrong in the cat’s system. We usually think of ear mites as the cause as they are so prevalent and readily pass between animals. However, many other factors such as food or environmental allergies, physical particles or blockages causing excess wax production or bacterial/yeast overgrowth may be at play. Monitoring your cat’s ears is one way to also monitor their overall health.

Source Notes

  1. Moriello, Karen A DVM, DACVD. “Otis Externa in Cats.” Merck Veterinary Manual – Pet Owners https://www.merckvetmanual.com/cat-owners/ear-disorders-of-cats/otitis-externa-in-cats
    last modified September 2024. Accessed July 15, 2025
  2. n.a. “Epithelial Cells” Science Direct https://www.sciencedirect.com/topics/medicine-and-dentistry/epithelial-cell Methods in Cell Biology, 2013. Accessed July 15, 2025
  3. Edgar, Julie. “Ear Infections in Cats: Causes, Treatment, and Prevention.” WebMD. https://www.webmd.com/pets/cats/ear-infections-in-cats-causes-treatment-and-prevention August 25, 2024 Accessed July 15, 2025
  4. Schick, Anthea DVM, DACVD. “Another Ear Infection? Dealing with Chronic Otitis” https://www.mmhimages.com/production/Creative/1OldBackup/fetch_Backup/CVC_KC_2017_proceedings_proof/data/PDFs/KC17PDFs/Dermatology/Another_ear_infection_STY.pdf Accessed July 15, 2025
  5. Kleszynski, Brittany DVM. “Ear Mites in Cats.” PetMD. April 29, 2024  https://www.petmd.com/cat/conditions/infectious-parasitic/ear-mites-cats   Accessed July 15, 2025
  6. Rosychuk, Rod A.W. DVM, Diplomate ACVIM. “Feline Ear Disease: So Much More Than ‘Ear Mites’” https://www.cabidigitallibrary.org/doi/pdf/10.5555/20093018657 Accessed July 15, 2025

 

 

Teresa Keiger

Teresa Keiger is Cat Talk’s editor and has been with the publication since 2013. She has been a professional graphic designer and photo retoucher since the mid-1990’s and currently creates many of CFA’s images. She has bred Russian Blues under the Platina Luna cattery name since the mid-1990’s and is a CFA Allbreed Judge.