Ear Mites (Feline)

by Petside Team

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Common name: Ear mite infestation
Scientific name: Otoacariasis, Parasitic otitis

Diagnosis

Signalment
While all cats are susceptible to ear mite infestation, those living in crowded environments such as shelters or catteries are at higher risk. The severity of infestation varies from animal to animal but is usually greater in kittens and adolescent animals than in adults.

Incidence/prevalence
Ear mites are the leading cause of feline otitis externa (ear infection), accounting for at least half of all cases.

Geographic distribution
Ear mites can be found throughout the world but are most prevalent where large numbers of cats live in close quarters. Stress and poor husbandry in confined situations favor mite proliferation.

Clinical signs (primary, most to least frequent, scientific term, synonyms)
Pruritis (itching) characterized by scratching at the ears, head shaking or ear twitching. Brown to black waxy exudate in the external ear canal. This discharge is usually dry and crumbly, with a flaky or granular appearance. Occasionally, white specks are visible in the debris. Excoriations (scratch marks), scabs and alopecia (hair loss) around the ears can result from persistent pawing at the ears. Miliary lesions (tiny pink to red bumps in the skin caused by inflammation) can occur on or around the ear.

Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Auricular hematoma (accumulation of blood in the earflap) can result from violent head shaking or scratching at the ear. Initially, the earflap appears puffed like a pillow. Left untreated, the auricular cartilage can break down, giving the pinna (earflap) a cauliflower appearance. Bacterial otitis (infection of the ear with bacteria) can develop from scratches, producing a purulent (pus) component to the discharge.

Otitis media (inflammation of the middle ear) may occur if infestation becomes progressive. With this more severe manifestation, a head tilt, circling or convulsions may develop. Some hearing impairment could result from auditory canals being plugged with exudate.

Cause (scientific, common term)
Otodectes cynotis (ear mites).

Organ systems affected (most to least affected)
Ear canal, Ear and surrounding skin.

Diagnostic tests
Examination using a lighted, magnifying otoscope often allows visualization of mite movement within the ear canal. Microscopic examination of the waxy discharge placed on a slide with mineral oil can reveal the presence of mites ‚swimming‚or eggs, floating in the oil.

At home, a small sample of the waxy discharge can be taken from the ear, placed on a black background and observed with a hand magnifying glass. Mites appear as moving white specks, about the size of a pinhead.

Differential Diagnosis
Flea bite hypersensitivity, Malassezia dermatitis (yeast infection), Allergic dermatitis, Notoedres cati (head mange), Pediculosis (lice).

Overview

Ear mites are the most common cause of outer-ear problems in cats. These tiny parasites, known as Otodectes cynotis, live in the external ear canal and feed on dead skin and blood. A dry, flaky or crumbly discharge that is brown to black in color is typically seen in the ears. If a heavy load of mites is present, a white grainy component may be visible in the debris.

Infestation usually occurs in both ears and can cause intense irritation. Scratching, rubbing the ear, head shaking and ear twitching are the most frequent signs exhibited by affected cats. The degree of itching varies among individual cats. In some instances, a cat will show hair loss around the ears, contract a secondary bacterial infection in the ear or develop a hematoma on the earflap.

Mites are passed through direct contact from cat to cat and even through close association with other pet species. This makes the condition especially problematic in multicat or multipet environments. While the severity of ear mite infestation differs with each individual cat, it is generally more severe in kittens and adolescent animals than in adults.

Treatment

Home Care
Due to the contagious nature of ear mites, it is important that all cats, dogs and other pets in the home are examined and treated if needed. Since mites can leave the ear canal and travel over the body, it is sometimes necessary to either bathe the cat with an insecticidal shampoo or apply a topical preparation. Vacuuming, cleaning and insecticidal treatment of the premises could also be required. Vacuum cleaner bags should be discarded after each use.

Professional Care
While ear mites can sometimes be seen by placing a small amount of ear exudate on a black background and examining it with a hand magnifying glass for moving white specks, confirmation should be made by a veterinarian.

Professional diagnosis is frequently performed by otoscopic inspection of the ear canal. It can also be confirmed through mixing a tiny sample of discharge with a couple of drops of mineral oil on a slide and examining under a microscope. Once the diagnosis is made, the veterinarian will devise a treatment plan to meet the needs of the individual patient.

Management begins with careful removal of excessive debris from the ear canal. This is usually followed with mineral oil drops or with commercial parasiticidal drops that may also contain agents to address inflammation, control excessive discharge, and treat any bacterial or yeast component. Alternatively, the plan could involve either injectable treatment or a monthly topical treatment, depending on the severity of the ear mites and the number and temperament of the animals in the household. Parasiticides should be used for 7 to 10 days to kill adult mites and eggs.

Action
It is very important to complete the recommended treatment course as directed to prevent mite eggs from developing into adults and re-infesting the cat, if treatment is stopped too soon.

Outcome
With proper diagnosis and treatment, ear mite infestation can be eradicated in the cat.

References/Additional Readings

Fooshee, S.K. Ear Mites. In: Norsworthy, G.D., ed.al. The Feline Patient. Baltimore: Lippincott Williams & Wilkins, 1998; 181-183.

Pedersen, N.C. Common Infectious Diseases of Multiple-Cat Environments. In: Pratt, P.W. Feline Husbandry. Goleta: American Veterinary Publications, Inc., 1991; 280-208.

Hendrix, C.M. Diagnostic Veterinary Parasitology. 2nd Ed. St. Louis: Mosby, Inc., 1998; 207-208.

Carlson, D.G., and Giffen, J.M. Cat Owner's Home Veterinary Handbook. New York: Howell Book House, 1995; 147-152.

Author
Donna Lohman, DVM

Editor
Steven Hansen, DVM, MS, MBA
DABVT, DABT