One of the most peculiar behaviors of pooches that almost always signals that something is wrong with your dog is incessant scratching of the ears or even vigorously shaking its head. And while there are quite a number of reasons why dogs scratch their auditory apparatuses, ear mite infestation may actually account for these two very common symptom. As a matter of fact, as we will learn in this article, ear scratching and head shaking are more often taken to be pathognomonic signs of the presence of ear mites in dogs.
What are Canine Ear Mites?
Ear mites in dogs almost always belong to the Otodectes cynotis species, although it is not uncommon to see other species of mites getting into the dog’s ear and initiating an inflammatory reaction. Mites are more of a problem of cats. However, because dogs and cats typically interact within a particular neighborhood or even within a single household, the chances of transmitting these species of mites from cats to dogs are high. This is because members of Otodectes cynotis have an uncanny ability to spread very fast. Even brief physical contact is enough to facilitate their transmission from one host to another.
Otodectes cynotis is a small spider-like pest that belongs to the class of mites that produce sarcoptic mange, the Sarcoptes scabiei canis. These inhabit the inner ear and typically feed on debris and other particles, especially cerumen, found in the auditory canal. They also take on a whitish color compared to other mite species that are darker. This can be helpful in the correct identification of the causative organism of otodectic otitis.
There is another species of mite that mostly affect the external surfaces of the ears including the surrounding skin, but never inside the ear canal. This type of mite is known as the Demodex canis, the main causative agent of demodetic mange in dogs. As such, if the infection occurs around and outside the ears, you can suspect Demodex canis to be the culprit. However, if the infection is inside the ears in the auditory canal, then you can expect Otodectes cynotis to be the main culprit.
What is the Life Cycle of an Ear Mite?
Canine ear mites have an average life span of only 3 to 4 weeks. Female Otodectes cynotis are known to lay about 4 to 5 eggs per day. After 3 to 4 days, the ear mite larvae hatch, transforming into nymphs. This stage of the ear mite’s development requires two sub-stages before an adult ear mite is formed. It should be understood that female ear mites only have about a week or so to lay eggs, after which they die. Female Otodectes cynotis are able to start laying eggs only after 3 weeks.
How does Ear Mite cause Disease in Dogs?
Otodectic otitis is the ear infection caused by Otodectes cynotis. As the organism finds its way into the ear canal of dogs, it latches onto the surface of the auditory canal. Its saliva contains proteins that act to dissolve some of the surface barriers of the ear canal so that it will be able to secure itself properly. These same proteins are what stimulate the dog’s immune system in mounting and inflammatory reaction in an attempt to make the internal environment a lot more unbearable for the ear mite. One of the pro-inflammatory substances released is cytokine which produces intense itching in the ear canal. In addition to cytokines, histamine may also play a role in the severity of the pruritus.
Unfortunately, the problem doesn’t really stop there. As ear mites in dogs destroy the superficial layer of skin inside the ears, secondary bacterial infections are not far behind. Bacteria and other harmful microorganisms gain entry into the deeper layers of the skin to produce some form of pyoderma as well as purulent otitis externa. Both secondary bacterial infections will require treatment approaches that are different from the management of otodectic otitis.
What are the Symptoms of Ear Mite Infection in Dogs?
We already mentioned that excessive scratching of the ear and intense shaking of the head are two of the telltale signs and symptoms of ear mites in dogs. These are brought about by the initiation of an immunologic reaction by the latching of Otodectes cynotis onto the epithelial surface of the ear canal. However, other symptoms of ear mites in dogs are also possible often related to these two primary symptoms. These include the following.
- Strong, often foul odor emanating from the inside of the ear
- The appearance of brown or black waxy secretion
- Partial obstruction of the dog’s ear canal
- Aural hematoma
- Black crusts that look like coffee grounds in the ear canal
- Scratches and / or abrasions on the back of the ears
- Secondary bacterial infections
One of the symptoms of ear mites in dogs that typically alarms pet owners is the appearance of black crusts that look like ground coffee beans in the auditory canal. These are actually dried blood. As the mite latches onto the skin of the inner surface of the ear, it punctures the skin and allows blood to leak out. Because blood naturally contains platelets, it clumps and dries up forming globs of black crusts.
How Can it Be Treated?
The ear mite treatment for dogs typically starts with a visit to your veterinarian to make a more accurate assessment of the symptoms of ear mites in dogs. Equally important is the correct identification of the causative agent. This is very crucial as many bacterial ear infections can mimic the clinical manifestations of otodectic otitis. If such is the case, then the appropriate antibacterial therapy is warranted. If the cause is clearly Otodectes cynotis, then the best ear mite treatment for dogs can be established by your vet. These can include the following.
- Acaricides: These are medications that are typically used in killing mites, including Otodectes cynotis. Ivermectin is one of the most commonly used acaricide when it comes to killing ear mites. What kills ear mites in dogs? Aside from Ivermectin, rotenone, pyrethrin, and fibronil as well as miticides like moxidectin/imidacloprid can effectively kill ear mites in dogs.
- Fungicides: Secondary fungal infections are a great concern in otodectic otitis. As such, your veterinarian may also order an antifungal agent to help treat any complications of fungal origin.
- Antibiotics: Just like secondary fungal infections, bacterial infections can also develop because of the loss of integrity of the skin. This allows the passage of bacterial organisms into the deeper layers of the skin causing an infection. In such cases, your vet will also order an appropriate antibiotic.
- Steroids: One of the cardinal signs of ear mite infection is inflammation of the auditory passages. Typically, the application of antibiotic miticides is often enough to reduce the severity of the inflammation. However, there are also cases when the dog is not simply responding to conventional therapies. As such, steroids may be ordered to help reduce inflammation.
- Ceruminolytics: The development or formation of waxy substances in the ear canal is generally increased in otodectic otitis. If allowed to progress, this can block the ear canal leading to a reduction in the dog’s hearing acuity. Ceruminolytics may be prescribed by your vet to help liquefy and loosen up this waxy buildup so that they can be easily removed with a mere shake of the head by your dog.
- Home remedies: There are several household products that have been shown to be quite effective against ear mites in dogs. Isopropyl alcohol, tea tree oil, vinegar, and coconut oil as well as a variety of plant-based extracts have shown promise as safer ear mite remedy for dogs.
Can it be Prevented?
Since mites are as ubiquitous as fleas and ticks, ear mite prevention should always be considered as part of the overall management of Otodectic otitis. The reason is quite simple. You may be able to get rid of the ear mite now, but this clearly doesn’t mean that your dog is not going to be reinfected anymore. Here are two simple ear mite prevention methods you can observe.
- Environmental controls: Otodectes cynotis does not really live in the ear canals of dogs. They live naturally in the outside world. Unfortunately, when cats pick them up and these feline pets interact or socialize with dogs, these ear mites inadvertently get transferred to dogs. As long as there is interaction between cats and dogs and as long as cats stray outside the home, the risk of otodectic otitis in dogs remains very high. It is for this reason that environmental controls should also be observed. All pets in a particular household should be treated for Otodectes cynotis. Pet beddings should be washed in hot water before being dried in your dryer in the hottest possible setting. Areas where pets frequent should also be thoroughly vacuumed. Spraying pet-safe miticides in your backyard can also help.
- Selamectin: This is a spot-on application that is structurally similar to Ivermectin. It can be applied on a once-monthly basis to help prevent ear mites from invading your dog’s ear canals.
Ear mites in dogs may only present as intense head shaking and ear scratching in dogs. However, their implications to your pooch’s overall health are not to be taken lightly. A combination of miticides, other pet-safe medications, and good old preventive strategies can help you manage otodectic otitis in your dog.
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- Malcolm Weir, DVM, MSc, Ear Mites in Cats and Dogs, VCA
- Ear Mites, Vetstreet
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.