Halloween – one of my favorite days of the year – is just around the corner! With this ghoulie holiday comes images of sorts of creepy crawlies that are sure to make your skin crawl. Did you know cats can be infested by various creepy crawlies? One of the most common critters are ear mites. Given the frequency with which this infestation is diagnosed, I’ve dedicated time this week to sharing information on this ear disease. Happy reading!
Ear Mites – What are they?
Ear mites, scientifically called Otodectes cynotis – is a highly contagious organism that lives either in the ear canal or on the surface of the skin. Ear mite infestation is the most common cause of otitis externa (inflammation of the external ear canal) is cats. Ear mites lay eggs with a sticky substance that adheres them to the skin or ear canal. After ~4 days, 6-legged larvae hatch, and they feed for 3-10 days; after that time, they hatch into 8-legged larvae called protonymphs and then again into a genderless phase called deutonymphs. These deutonymphs attach to adult male mites. If the deutonymphs become females, reproduction occurs. Mites feed on cells on the surface of the skin and external ear canal, creating irritation and inflammation.
Ear Mites – What do they look like?
Otodectes cynotis more commonly affects kittens since adults develop a resistance to infection. There is no breed or sex predilection for ear mite infestation. Ear mites cause intense pruritus (itchiness). Often times the pruritus is so intense that a cat will begin to the scratch with the pelvic limb on the same side as the ear being examined – this phenomenon is called the pinnal-pedal reflex. As a result of pruritus, a veterinarian often finds excoriations (scratches & abrasions) at the base of the ears, neck, rump, and tail caused by a cat scratching and/or chewing at these sites. This is a form of self-traumatization and cause predispose to secondary bacterial infections. Other skin lesions (called erupted papules) consistent with mite infestation may also be present – such skin lesions are called otodectic acariasis.
Ear Mites – How are they diagnosed?
Diagnosis of Otodectes cynotis infestation is quite straightforward. As part of a physical examination, a veterinarian will visually inspect the ears. Quite simply, an infested ear looks dirty. The external ear canal is filled with debris that is a mixture of cerumen (ear wax), blood, and mite material. As mentioned earlier, there is often evidence of self-traumatization around the ears and/or at various skin locations. To visualize mites, a veterinarian will do one of two procedures:
- Otoscopy – using a special videoscope, the veterinarian can look deeply in the external ear canal to directly visualize the ear mites (see video below)
- Microscopic examination of ear debris – the veterinarian will obtain a sample of the debris and examine it microscopically. Mites are readily visible, crawling around on the slide.
Ear Mites – How are they treated?
Thankfully treatment of ear mites is well-tolerated and effective. The first step to successful therapy is thoroughly cleaning the ears. The external ears canals must be cleared of as much debris as possible. After cleaning the ears, instillation of a mite-killing medication into each affect ear is needed – these types of medications are miticidal otic preparations. Rarely system miticidal medications are indicated.
Bathing infested animals is also appropriate to remove any mites that may be living on the surface of the skin. Otodectes cynotis is highly infective, readily transmitted to other animals (including dogs) in the household. As such, veterinarians often recommend treating all animals in the home even if they aren’t showing clinical signs. Rarely, Otodectes cynotis can even cause skin lesions in people (called transient popular dermatitis). The good news? With timely identification and appropriate therapy, the prognosis is excellent!
The take-away message about ear mites in cats & dogs…
Otodectes cynotis – more commonly called ear mites – is the most common cause of external ear canal inflammation in cats. Easily diagnosed with microscopic examination of ear debris, topical/otic therapy is typically readily successful.
To find a board-certified veterinary dermatologist, please visit the American College of Veterinary Dermatology.
Wishing you wet-nosed kisses,