Greetings fellow dog lovers! If you’ve had dogs all your life, like me, or are a new dog lover, I would like to take this opportunity to discuss otitis, which is the medical term used for irritated, inflamed ears. Most dog owners have had to deal with otitis. It can be very frustrating, and you can image how uncomfortable a dog is with a painful, irritated ear! Many causes of ear inflammation exist, including allergies, parasites and infections with bacteria or yeast. The focus of this article is parasitic causes of otitis; namely, the ear mite.
A Brief History Of Dog Ear Mites
The scientific name for the most common ear mite affecting dogs is Otodectes cynotis. When you dissect the name, which is Greek in origin, “oto” is ear, “dektes” refers to a “beggar” and “cynotis” is “of the dog.” It was first described in the mid 1800s, although by a different scientific name. Ear mites are found all over the world, including the Americas, Europe, Asia, the Middle East and Australia. They not only infect dogs, but also cats, foxes and ferrets. Approximately 5 to 10 percent of otitis in dogs is caused by ear mites.
The Ear Mite Life Cycle
Ear mites live in the ear canal where they reproduce to complete their life cycle. Female ear mites lay eggs that attach to the canal by a glue-like secretion. Eggs incubate for approximately four days and then hatch into larvae. The larvae undergo more life-stage growth resulting in protonymphs and deutonymphs, each taking three to six days to complete. So, to grow from one egg to a mature nymph that mates and then lays new eggs takes three to four weeks.
How Dogs Get Ear Mites
Dogs spread ear mites to each other through direct contact. Therefore, dogs in animal shelters, humane societies, boarding kennels and even “doggie day care” venues are more likely to be affected than dogs who don’t “meet” other dogs. Cats, who have a much higher rate of infection with ear mites than dogs, can also infect their dog companions. The mites and eggs need a humid environment to survive, around 80 percent humidity. That is the reason why dogs with “floppy” ears tend to have more infections than those with upright ears. Another interesting fact is that ear mites don’t need to feed on live skin cells or blood; they scavenge debris from wax and dead cells. However, they will also feed on live cells and bodily fluids, such as plasma.
Signs That Your Dog Has Ear Mites
Symptoms of ear mite infection mimic those of other causes of otitis. Inflammation noted by swelling, redness and pain is very common. Head shaking, scratching, excessive, dark earwax or cerumen are common signs, too. The irritation and itchiness can be so severe that dogs will scratch to the point of breaking their skin open, and may bleed from the area around the ear and the ear itself!
Diagnosing Ear Mites In Dogs
Diagnosis is relatively easy. When you take your dog to the veterinarian with a complaint of irritated ears, the vet will do a thorough ear exam using an otoscope (lighted hand piece with a magnifier) and may identify the mites in the ear canal. The mites look like small specks of white sand that crawl around. Additionally, samples of the ear debris can be examined microscopically to identify the parasite. Under the microscope, the ear mites look like tiny ticks.
Treatment For Dog Ear Mites
Once diagnosed, you and your veterinarian can discuss a course of treatment. Possible treatments include the use of topical medication, or injections using a drug called ivermectin. Flea and tick preventives placed on the skin between the shoulders have also been found to be effective. Most topical treatments contain an insecticide, pyrethrin or rotenone. These treatments are safe and formulated to be used topically in the ear canal. About a week of treatment with a topical ear product will eliminate the ear mites.
Heartworm preventives can also be used and are either placed topically on the skin (not in the ear canal) or injected. Typically one or two doses are all that is needed to kill the ear mites. These products are safe for most dogs; however, there are certain breeds, such as Collies, Shetland Sheepdogs, Border Collies, Greyhounds and Australian Shepherds (to name a few), who cannot be treated with these drugs. These breeds have a genetic mutation affecting their MDR1 gene (multi-drug-resistant 1 gene).
The MDR1 gene codes for a protein (P-glycoprotein) that protects cells from drugs by literally pumping them out of the cell. Dogs with the MDR1 mutation are susceptible to toxicities from certain drugs like ivermectin and will become very sick and may die from exposure to these ear mite treatments (and many other drugs, such as opioids and anti-cancer drugs). Veterinarians are very familiar with this mutation and, if suspected, can have your dog tested for the mutation.
While otitis can be a painful problem for dogs and require extensive treatment, infection caused by ear mites is easy to diagnose and treat. Hopefully, you dog will never have an ear infection, but you and your furry friend have many options if it’s caused by ear mites.