The Classic Comprehensive Handbook of Cat Care
What to Do When Your Cat Is Sick: ears external ear inflammation (otitis externa)
Otitis externa is a term used to describe an inflammation of the external ear (outside of the eardrum). It has many causes, but the signs are usually the same. Head shaking and scratching at the ears are probably the most common. In some cases the cat will tilt the head slightly toward the side of the irritated ear; touching the ear may cause signs of pain.
Large amounts of waxy discharge are often present; in severe cases there may be actual pus. The inside of the pinna is sometimes abnormally pink, and there may be swelling. (See Anatomy, if you are not familiar with a normal cat ear.) The normal smell of a healthy cat ear becomes fetid as the inflammation gets worse.
EAR MITES OFTEN CAUSE OTITIS
The most common cause of otitis externa of cats is probably ear mites. If you cannot be sure that ear inflammation in your cat is caused by mites or if you are not sure you can treat the problem at home, enlist the aid of a veterinarian. Ear inflammation not treated promptly and vigorously can result in ear conditions that could have been easily cured at first but are now difficult or impossible to treat successfully, and the infection can progress to include the middle and inner ear. If you are unable to obtain the services of a veterinarian and don’t think the ear problem is caused by ear mites or a foreign object in the ear (rare in cats) and choose to attempt home treatment, try using 70% isopropyl alcohol (rubbing alcohol), 10% povidone-iodine solution, or 0.5% chlorhexidine solution. First clean out the affected ear.
Then twice a day, after a more minor ear cleaning, instill several drops of the disinfectant into the ear canal and massage the base of the ear to spread the medication all the way down the canal. If you see improvement within three or four days continue treatment for two weeks. If there is no improvement or if the treatment seems too irritating to your cat’s ear, be sure to seek professional help, since there is risk of permanent damage to the middle ear if home care is inappropriate.
YEAST INFECTIONS ARE FOUND IN CATS
A yeast, Malassezia pachydermatis, is found in as many as one-third of cat ear infections. Signs of discomfort that may range from mild to severe are often associated with a brown, waxy discharge when excessive numbers of these organisms are present. Usually an increase in ear scratching is seen. This yeast thrives in a warm, moist environment. A microscopic examination of debris associated with this type of ear inflammation is needed to be sure the yeast is present and significant.
Ears that are kept clean, dry, and slightly acid in pH are less likely to develop excessive numbers of yeast; so predisposed cats often need a routine of home ear care to prevent repetitive problems. Commercial products containing alcohol and boric acid, instilled into the ears once or twice a week, can prevent yeast-associated otitis externa. Home remedies for prevention are white vinegar (5% acetic acid) diluted 1:1 with water or 70% isopropyl alcohol instilled once or twice a week and after bathing.