Demodectic Mange in Dogs

brown and white dog

Mange is an external parasitic disease that can be caused by a variety of pathogenic agents from various species. Demodectic mange is perhaps one of the most challenging to treat of all mange varieties, even though it tends to affect dogs with less capable immune systems more than it does their counterparts.

Today’s article looks at everything you should know about demodectic mange in dogs – from its causes and symptoms to its diagnosis and treatment.

What Causes Demodectic Mange?

At the root of this condition stands a parasite called ‘Demodex canis,’ which is basically a microscopic mite that creates burrows inside your dog’s skin layers.

There are three main types of Demodex mites that affect this species, and they are the following:

  • D. canis
  • D. gatoi
  • D. injai

The first is the most common one to be diagnosed in dogs. The parasite often lives in symbiosis with the host, which means that most dogs that carry the parasite in their dermal layers might not show any symptoms at all.

However, if they suffer from chronic disease, are younger than 12 to 16 months of age (and therefore, their immune system hasn’t fully developed), or are seniors, they might show severe clinical manifestations.

Is demodectic mange contagious? While it hasn’t been proven despite years of research, it’s not unfair or incorrect to assume that dogs that live in the same household or in locations where they often come in contact with other animals (such as shelters) have a much higher risk of developing a clinical form of this disease.

Even if they are not carriers but share the same living space with a dog that clearly has mange, they might catch some of the parasites through direct or indirect transfer.

The most common way of transmission of D. canis is the mother giving it to the pups, but since many adult dogs are inapparent carriers, they can easily develop more severe manifestations with an abundance of parasites causing the lesions.

Symptoms of Demodectic Mange in Dogs

There are three main types of clinical manifestations when it comes to this disease:

  • Localized

This type is characterized by the appearance of the lesions in one or two (tops) locations across the dog’s body. It is more common in young dogs, especially those that haven’t had their 1st birthday.

Some of the more common symptoms of this type are hair loss and average inflammation in certain body areas, especially around the eyes or somewhere on the dog’s face and in a random region such as the back, ribs, or underbelly area.

If the dog’s immune system begins to function normally and they (hopefully) receive treatment in due time, this type usually resolves in a short amount of time.

  • Generalized

This is one of the most challenging types that exist. Dogs exhibit the same lesions, such as mild or severe skin inflammation and complete hair loss in several areas across their bodies (sometimes more than 75% of their entire body surface).

Due to skin inflammation, secondary bacterial infections involving opportunistic pathogens might show up in certain regions.

The problem that arises, in this case, is that since demodectic mange is often treated with very harsh topical insecticides (such as Amitraz), vets obviously can’t use these substances on the areas where the dog has also developed bacterial dermatitis – or else they would cause burns or make the lesions more severe.

This is why treatment for generalized demodicosis can often be very lengthy.

  • Pododermal

This type is characterized by all or most of the lesions being located in the paw areas. Unfortunately, they don’t only show up on the top surface of the paws but also in-between the dog’s toes.

And if there is one area on your dog’s body not benefiting from enough ventilation, that is their foot area.

Dogs that have long hairs in-between their toes have a higher risk of developing severe local lesions as the hair makes it impossible for the lesions to undergo a normal drying and scarring process.

How Is Demodectic Mange Diagnosed?

Diagnosing demodicosis in dogs is relatively simple. The veterinarian will scrape a portion of the dog’s skin (not one that has sustained any damage or has been affected by bacterial dermatitis, of course) and examine it under the microscope.

Sometimes, a living parasite might not be present in that portion of skin, but there could be pieces of dead parasites that have the exact anatomy of a D. canis.

Can Canine Demodectic Mange Be Treated?

Yes.

There are three main ways of treating and preventing canine demodectic mange. And while they might not lead to the elimination of all of the parasites, most of them will be decimated, so the pet’s skin will have the opportunity to recover naturally.

Amitraz is an insecticide that is used topically, but it requires a complete body rinse. This makes it one of the most challenging therapies, although perhaps one of the most readily available ones right now.

A Dectomax injection that’s given once a week for a period of 4 to 6 weeks (depending on the severity of the symptoms) can be another option and an entirely reliable, convenient, and effective one.

Finally, there’s also the option of using a topical solution such as Advocate (containing both Moxidectin and Imidacloprid) that you can apply to your pet’s neck once every 4-6 weeks. Although it is relatively effective as well, generalized and severe forms of the disease often call for more aggressive therapy choices (such as Amitraz).

Prognosis and Recovery

If your dog is otherwise perfectly healthy and they are not showing any other symptoms, they might recover from demodicosis in a period of two to three months.

The reason it takes so long is that you have to regularly take your pet to the veterinary clinic so that they have their skin scraped and tested for D. canis. Once they are considered clear of demodectic mange, you should apply topical solutions once a month for at least several months to come.

If you ever leave for vacation and plan on leaving your dog in a kennel or whichever type of accommodation where many other dogs are present, make sure they are fully vaccinated and that they have received a shot of Dectomax just for good measure.

References

Updates on the management of canine demodicosis, Sandra N. Koch, DVM, University of Minnesota, 2017 https://todaysveterinarypractice.com/wp-content/uploads/sites/4/2017/01/TVP_2017-0102_Column_Dermatology-Details_AUTHORPDF.pdf

Efficacy of a topical application of Certifect® (fipronil 6.26% w/v, amitraz 7.48% w/v, (S)-methoprene 5.63% w/v) for the treatment of canine generalized demodicosis, Josephus Fourie et al, 2013 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3834659/

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