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Ear Infections (Otitis Externa) in Cats
Veterinary & Aquatic Services Department, Drs. Foster & Smith
Grooming and Sanitation
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Click here for a pdf version of this article.  See related products at Pet Supplies

Cat scratching ear"My cat's ears have a terrible odor. What could it be?" "My kitten has been scratching her ears. The ears have dark, crumbly material in them. What should I do?" These are some of the most commonly asked questions of veterinarians.

Signs of ear disease

Every day we see cats who have problems with their ears. Signs of these ear problems include:

  • Odor
  • Scratching or rubbing of ears and head
  • Discharge in the ears
  • Redness or swelling of the ear canal
  • Shaking of the head or tilting it to one side
  • Pain around the ears
  • Changes in behavior such as depression or irritability

Ear disease is one of the most common conditions we see in pets. The medical name for inflammation of the outer ear canal is 'otitis externa.' One study found that from 2% to 6.6% of cats admitted to hospitals were presented because of otitis externa.

Causes of ear disease

Cats can have ear problems for many different reasons. When we see a cat with ear disease we need to think about the possibility of:

  • Allergies such as atopy or food allergies
  • Parasites - ear mites
  • Microorganisms - bacteria and yeast
  • Foreign bodies, e.g., plant awns
  • Trauma
  • The ear environment, e.g., excess moisture and ear anatomy
  • Hereditary or immune conditions, and tumors

Allergies: Cats with allergies, either to food or something they inhale, may have ear problems. As a matter of fact, the ear problem may be the first sign of the allergy. Since the allergy changes the environment within the ear, we sometimes see secondary infections with bacteria or yeast. If we just treat the infection, we are not getting to the root of the problem. We need to treat the allergies too.

Parasites: The ear mite, Otodectes cynotis, is a common cause of ear problems especially in kittens. Some animals are hypersensitive to the mites and the resultant itching can be intense. These animals may scratch so much they severely traumatize the ear.

Bacteria and Yeast: Numerous types of bacteria and the yeast, Malassezia pachydermatis, cause ear infections. The normal, healthy ear has a good defense against these organisms, but if the ear environment changes due to allergies, hormone abnormalities, or moisture, the bacteria and yeast can greatly multiply and break down these defenses.

Foreign Bodies: Plant awns, those little "stick-tights" that cling to our clothes and our cats' fur, can sometimes enter the ear canal. Their presence causes irritation, the cat scratches, and before you know it we have a traumatized, infected ear. So if you have a cat who goes outside, be sure to routinely check the ears.

Trauma: As we described above, self-inflicted trauma to the ear due to scratching can exacerbate ear problems.

Hormonal Abnormalities: Deficiencies or excesses of various hormones can result in skin and ear problems. Thyroid hormone, glucocorticoids produced by the adrenal gland, and sex hormones all influence the health of the skin and ears.

Ear Environment: Bacteria and yeast could not ask for a better environment to live in than a warm, dark, moist ear canal.

Other Causes: There are various rare hereditary diseases that occur in different breeds or lines and affect the ears. Eosinophilic granulomas are related to a disorder of the immune system and can occur in the ears of cats. Squamous cell carcinomas, melanomas, and other tumors can be seen in the ears.


Because there are many potential causes of ear problems, we cannot just say it is a bacterial infection, dispense antibiotics, and it will go away. Often more work is needed. Your veterinarian can use an otoscope to look down into the ear canal and determine the amount of inflammation present, if the tympanic membrane (ear drum) is involved, and if there are any foreign bodies, tumors, or other potential causes of the problem. Swabs of the ear can be taken, smeared on a microscope slide, stained and examined for bacteria, yeast, and mites. A thorough history and physical exam may help determine if this could be a hormonal, allergic, or hereditary problem. If these are suspected, further diagnostic testing would be needed. If a bacterial infection does not respond to the first antibiotic therapy, a culture and sensitivity may need to be performed to select a different antibiotic.


The treatment is going to depend on what caused the ear problem and what secondary conditions are there as a result. Antibiotics are used for bacterial infections and antifungals for yeast infections. Glucocorticoids such as dexamethasone are often included in these preparations to reduce the amount of inflammation in the ear. Ear problems caused by a systemic disease such as a hormone abnormality or allergy must include a therapy that treats the whole cat, such as hormonal replacement or allergy testing and hyposensitization (immunotherapy).

Allergies: Allergies are commonly treated with regular ear cleaning with an ear cleaning solution, antihistamines, and fatty acid supplements. Sometimes corticosteroids are needed. These may be given in an oral or injectable form, or they can be applied topically. Allergy testing and immunotherapy (hyposensitzation) may be the best way to cure the ear problem.

Ear mites: Ear mites can cause a dry, dark, crumbly debris in the ear that resembles coffee grounds. Ear mites are more common in cats than dogs. For this condition, ear cleaning followed by an ear medication to kill mites will eliminate the problem, although the treatment may need to be continued over several weeks depending upon the product used.

Yeast: Yeast can cause severe ear problems. We usually observe a brown waxy exudate and a bad odor. Daily cleaning of the ears will help, but often these infections are difficult to treat, and special medications need to be given since antibiotics do not kill yeast. If you suspect a yeast infection in your cat's ears, consult your veterinarian.

Bacterial Infections: Bacterial infections can also have a bad odor and often have a more yellowish exudate. If it is a severe or chronic condition, ear cleaning alone will not take care of the problem and antibiotics will almost always be necessary. Again, consult your veterinarian. Ear infections of the canal, if severe, can spread to the middle and inner ear, so prompt attention to the problem is always best.

Regardless of the cause of the ear disease, we must always keep the ear canal clean.

Cleaning ears

Ear DiagramYour cat's ear is more L-shaped than yours, and debris loves to collect at the corner of the L. To remove this debris, fill your cat's ear canal with a good ear cleaner. Ear cleaners should be slightly acidic but should NOT sting. Massage the base of the ear for 20-30 seconds to soften and release the debris. Wipe out the loose debris and excess fluid with a cotton ball. Repeat this procedure until you see no more debris. Depending on your cat's ear condition, you may have to start out doing this twice a day.

Cotton applicator swabs can be used to clean the inside of the earflap and the part of the ear canal you can see. They should NOT be used farther down in the ear canal since that tends to pack debris in the ear canal, rather than removing it.

Some ear problems are so painful, the cat must be anesthetized to do a good job of cleaning the ears. You may find your cat does not like to have her ears cleaned because it is uncomfortable. Talking to her during the process, stopping momentarily to give her a treat if she is doing well (we do not want to reward fussiness!) and doing something fun afterwards may all help.

After the ear is clean, let the cat shake her head and allow some time for the ears to dry. Then you can apply any ear medication that was prescribed.

For more help, see our video on How to Clean Your Cat's Ears.

Preventing ear disease

Cleaning a cat's earThe key to healthy ears is to keep them clean. Check your cat's ears weekly. A slight amount of waxy buildup may be present in normal ears. Treat any underlying condition that predisposes your cat to ear problems.

Remember, if your cat is showing severe discomfort, the ears have a bad smell, or the ear canals look very abnormal, do not delay in contacting your veterinarian. If your cat has a ruptured or weakened eardrum, some ear cleansers and medications could do more harm than good.

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