No, they are not. Foul smelling discharge and a heavy build-up of ear wax are also abnormal. Dog and cat ear skin should be pink and without excess wax or moisture. Pets that frequently shake their heads, scratch their ears, rub their ears along furniture or have swollen, red or moist ears may be exhibiting signs of discomfort due to ear disease.
Ear diseases are quite common in dogs and have been reported in up to 20% of dogs1
. Because ear disease occurs much less frequently in cats at an incidence rate 2-6%2
, we will focus on the canine ear in this article.
There are multiple factors that contribute to ear disease. Genetics, behavior, bacterial/fungal infections, dermatologic disease, diseases of the endocrine system and parasites can all cause ear disease. Diseases of the ear are noted as otitis externa when they affect the external ear canal, otitis media when they affect the middle ear canal and otitis interna when they affect the inner ear canal. Ear infections left unchecked can cause permanent damage including deafness in canines.
Genetics can play a role in ear disease. German Shepherds and other dogs with erect ears have good ventilation of the ear canal. Cocker Spaniels, Basset Hounds and other “floppy eared dogs”, on the other hand, can be prone to ear disease. With folded ears, the ear canal has decreased air flow. Folded ear canals are dark, warm environments that can provide ideal growth conditions for bacterial, yeast and fungal infections.
Behavior of both pets and their owners can predispose them to ear disease. Dogs who love to swim and bathe tend to have wet ears and wet ear canals. This leads to more moisture and therefore higher humidity in their ear canals. High moisture and humidity can promote overgrowth of bacteria and yeast that occur normally in the ear. Overzealous ear cleaning either with an abrasive tool, material or chemical by owners can also lead to damaged epithelial cells and allow overgrowth of bacterial and fungal organisms. Cats have a very unique ear canal design and fluids are not easily removed from the feline inner ear canal. Cleaning solutions therefore are likely to remain in the ear canal for extended periods of time. Cats have specific nerve innervation that courses between portions of the ear canal. Damage to this nerve can occur during overzealous cleaning by owners and can lead to a specific condition called Horner’s Syndrome.
In both dogs and cats, bite/fight wounds, burns and vehicular trauma can lead to secondary infections. Cats are more likely to have parasitic infestations due to the ear (Otodectes sp.) mites than dogs are.
Like any other medical condition, diseases of the ear should be diagnosed and treated by a licensed veterinarian. Proper ear cleaning techniques should be demonstrated to owners in a veterinary clinic before ear cleanings are attempted at home.
1 Merck Animal Health. Otitis externa. https://www.merck-animal-health-usa.com/dp/38
2 Griffin, Craig E. (2010, October 31). Otitis in cats: what is different from dogs (Proceedings) dvm360. https://www.dvm360.com/view/otitis-cats-what-different-dogs-proceedings