Ear Mites in Dogs
Diagnosis and Treatment Options
by: Laura McLain Madsen DVM
What are dog ear mites?
Ear mites in dogs are caused by tiny spider-like parasites with eight legs. One type is the ear mite (Otodectes cynotis), which infects dogs and cats. Ear mites live primarily in the external ear canal but also roam around the dog’s body. They are transmitted from animal to animal by direct contact (such as by playing or sharing a bed). The mites eat skin debris, ear wax, and skin oils, and lay eggs which are sticky to attach to the dog’s fur. The ear mite life cycle (from hatching to adulthood) is three weeks.
What are the symptoms of ear mites in dogs?
Ear mites usually cause itchiness. Dogs with ear mites frequently scratch their ears and shake their head. The ears are sensitive and dogs might yelp or flinch when the ears are touched. Sometimes dogs will be itchy all over their body, not just the ears, due to the mites wandering away from the ears.
When you flip up the dog’s ear flap and look at the opening of the ear canal, the skin will be red and inflamed. There is often a dry, brown-black, “coffee grounds” discharge in the dog's ear canal. There may be bleeding scratches from self-trauma and hair loss behind the ears from rubbing.
In severe cases, dogs can develop an aural (ear) hematoma as a consequence of scratching and shaking. A blood vessel bursts between the layers of the ear flap, and the flap fills up with blood. You won’t see the blood, but the flap of the ear is thick and feels like a water balloon.
It’s important to realize that not all ear infections are caused by dog ear mites. In fact, in adult dogs, ear infections are more commonly caused by bacteria, yeast, and/or allergies. All kinds of ear infections will cause similar symptoms of ear-scratching, head-shaking, pain and redness.
Which dogs are at risk?
All dogs are susceptible to ear mites, although infections are seen more commonly in puppies and in dogs who are in close contact with other animals, such as going to dog parks and day cares, in shelters, or in households with outdoor cats.
Are ear mites in dogs contagious to other pets?
Ear mites are highly contagious to other dogs and also to cats. All dogs, cats and ferrets in the household should be treated, even if they aren’t all showing symptoms.
Are dog ear mites contagious to people?
Fortunately, no. The mites won’t set up residence in a human’s ears, although they could cause a temporary rash if they bite.
How are ear mites in dogs diagnosed?
Dog ear mites are just barely visible to the naked eye, but are better seen with magnification. When your veterinarian looks into the ear canal with an otoscope, he may be able to see the mites moving around. You vet will likely recommend taking a sample of the ear discharge with a swab for cytology, to examine under a microscope. Through the microscope the ear mites show up quite clearly. With cytology of the ear discharge your veterinarian will also be able to determine if there are other causes of ear infection, such as bacteria or yeast.
What is the treatment?
Your veterinarian will first clean out the ears to remove the debris clogging the ear canal. Removing the discharge allows your veterinarian to visualize the ear drum to make sure it hasn’t ruptured, and also makes topical medications more effective. A variety of medications can be used to kill the mites, including topical (applied to the ear) and systemic (circulating throughout the body).
If only a topical is used, it is recommended to wash the dog with a flea shampoo to kill wandering ear mites. It may also be necessary to treat with anti-inflammatories if the ears are very inflamed and painful, or antibiotics if there is a concurrent bacterial infection. And remember, every pet in the home must be treated, even if they’re not showing symptoms, to prevent the mites from transferring back and forth.
Topical medications (put into the dog's ear canals) include:
• Milbemite® (milbemycin) is not FDA-approved for use in dogs, only cats, but has been shown to be safe and effective in dogs as well.
• Acarexx® (ivermectin) is also only FDA-approved for the treatment of ear mites in cats, but is effective in dogs as well. Collies, Shelties, Aussies and related breeds may be very sensitive to ivermectin; it can cause neurologic side-effects and death. The topical use of ivermectin is not as risky as injections but should still be used very cautiously in Collie-type breeds.
• Tresaderm® (thiabendazole, an anti-parasitic and anti-fungal drug, plus neomycin, an antibiotic, plus dexamethasone, a cortisone-type anti-inflammatory) treats bacterial, yeast and ear mite infections. It must be used daily for at least 10-14 days.
• Frontline Plus® (fipronil), a topical flea and tick preventative, also is effective against ear mites. For fleas, Frontline Plus® is applied to the skin on the back of the shoulders, but for ear mites a smaller dose (two drops per ear) can be applied directly in the ears.
• Various over-the-counter drops containing pyrethrins (Cerumite®, Otomite®, Mita-Clear®, Eradimite®) can be effective, but need to be used regularly for three weeks (the duration of the mite life cycle).
• Mineral oil and baby oil are old-time remedies, and work by drowning the mites. The newer medications are more effective and much less messy!
• Home remedies like garlic or olive oil are not recommended, as they are minimally effective and may worsen the ear infection.
Systemic medications (circulate through the whole body) include:• Selamectin (Revolution®)
comes as a small vial of liquid which is applied to the skin on the back of the shoulders. Although it is applied topically, the drug acts systemically. Revolution® is absorbed across the skin into the bloodstream. It kills a variety of dog parasites
, including ear mites, sarcoptic mange mites
, fleas and roundworms, and is also a heartworm preventative. Revolution® lasts up to a month after administration, so a single dose may be sufficient to cure an ear mite infestation, but usually a second dose will be required 2-3 weeks after the first dose. Revolution® should not be used in puppies under six weeks of age or in sick or underweight puppies, but is safe in pregnant and nursing bitches.
• Advantage Multi® (imidacloprid plus moxidectin) is applied topically but absorbs systemically, like Revolution®. Advantage Multi® also kills fleas and intestinal worms, and is a heartworm preventative. It should not be used on puppies less than seven weeks of age or three pounds.
• Ivermectin (Ivomec®) is an injection given by your veterinarian. Like Revolution® and Advantage Multi®, ivermectin kills a variety of parasites. The injection is usually repeated two weeks later. Ivermectin injection should not be used in Collies, Shelties, Aussies or related breeds, as it can cause neurologic side-effects and death. An accidental overdose in any breed can be fatal.
What is the prognosis for ear mite infections?
Dog ear infections due to mites are generally straight-forward to treat. If there are compounding factors, like a bacterial ear infection, treatment might be more difficult. Dogs don’t develop any sort of immunity against mites, so a dog who has recovered from ear mites is still at risk of being re-infected in the future.
How can I prevent ear mites in dogs?
If your dog is at risk of ear mite infections (such as a dog who lives with outdoor cats), keeping him on monthly Revolution® or Advantage Multi® will prevent ear mites, as well as preventing other parasitic infections (heartworm and intestinal parasites).
If your dog is showing symptoms of ear mites, it’s best to schedule an exam with your veterinarian to make sure the infection isn’t caused by other infectious agents, and to ensure optimal treatment for your pet.
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