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Dog Diseases: Demodex


Alex is a marine biologist, aquarist, lover of animals, an experienced veterinary assistant, and has a Bachelor of Science in Biology.

What Is Mange?

Mange is a nasty skin disease, and there are two kinds that affect dogs: sarcoptic and demodectic (referred to as "demodex"). Both forms are caused by mites living around the skin of the dog. With sarcoptic mange, the mites live just under the surface of the dog's skin, whereas the mites associated with demodex (Demodex canis) live in the hair follicles themselves. Of the two, demodex is more commonly seen.

How Dogs Acquire Mites

On a healthy dog with a fully functioning immune system, a few mites will not cause any problems. However, if a dog has a compromised immune system or an immune system that is immature, it will be susceptible to the mites. Interestingly enough, most puppies get mites from their mother in their first days of life. The good news is there is a cure for demodectic mange. The bad news is that the treatment process is long and can get rather expensive.

How Much Does It Cost to Treat Mange?

If you have ever had a sick dog before, it should come as no surprise that treatments can be expensive. Demodectic mange is no different, in fact, it is going to be a long and expensive road to recovery. While localized mange can be cleared up fairly quickly with a little miticide shampoo and dips, generalized mange is not so lucky (as defined below). The treatment for generalized mange is going to last several months and cost several hundred dollars.

However, new medications come on the market all the time. Some flea/tick prevention, particularly newer oral prevention, can be used to treat mange off label. What does off label mean? This means that studies have been done that show a medication can be used in conditions other than what is on the label. For something to be included on the medication label it must have been shown to be effective in studies, which takes time and costs money so not all manufactures are interested in adding to an existing label.

When considering treatment options your veterinarian will choose the best course for your dog.

Localized and Generalized Demodectic Mange

Demodectic mange can be further broken down into two categories: localized and generalized.

Localized Demodex

Localized demodex typically occurs in puppies or dogs under a year of age. The hallmarks of this disease are:

  • thinning fur around the mouth
  • thinning fur around the eyes
  • small patches of hair loss

It is important to note that if more than five patches are present at one time, it is possible that the disease is progressing to the generalized form. It is not unheard of for the localized form to clear up on its own, reappear in a few weeks, and then clear up again.

Generalized Mange

Generalized mange is more widespread than the localized form. The hallmarks of this disease are:

  • patches of hair loss that progress to large areas of hair loss
  • fur that is not able to grow back as the follicles are completely filled with mites and dead skin
  • skin that is extremely delicate and covered in crust
  • open sores on the skin
  • pockets of infection under the skin

There have been some cases where young dogs, one year or younger, have developed generalized demodectic mange and it cleared up on its own. However, this should not be expected in all cases. Thankfully, there are treatments available for both forms.

Content Warning

There are some graphic pictures in this article.

A Boston Terrier puppy with generalized demodectic mange.

How Is It Diagnosed?

So, how exactly is demodectic mange diagnosed? As an average pet owner, chances are pretty good that you will not be able to tell the difference between sarcoptic and demodectic forms of mange. All you are going to see is that your dog is losing fur, is covered in scaly skin, and may have open sores.

Skin Scrapings and Microscopic Examination

Your veterinarian will do a skin scraping to determine the exact cause of fur loss. Essentially, your vet is going to gently scrape the dog's skin at different locations throughout the body. They will then create a slide and check for mites under a microscope. In the case of demodectic mange, a large number of mites will typically be present on the slide. The skin scraping will then be completed several times throughout the treatment process to ensure that the treatment is working.

The Pinnal-Pedal Reflex Test

The pinnal-pedal reflex test is sometimes used to identify the presence of mange by lightly touching the ear of the dog. If the dog has mites in its skin or ears, the dog will move its foot in a scratching motion. However, this test will also be positive for ear mites, and it cannot determine which type of mite is present.

How Is It Treated?

Veterinary medicine has come a long way in the last few years. Just a few decades ago, dogs with the generalized form were considered untreatable. While it is true that some dogs have spontaneously healed from both localized and generalized mange, it should not be expected. The best thing that can be done for a dog with either form is to take them to a veterinarian and for the veterinarian to set up a treatment plan for the dog.

Treatments for Localized Mange

Localized demodectic mange can be treated with topical medications. Treatment typically involves the same cleaning solution that is used on ear mites or benzoyl peroxide topical. The veterinarian will prescribe these medications and instruct that they be rubbed into the affected areas at least once every day until the condition clears. Both of these drugs will help shorten the lifespan of the mites. It is possible that the skin might look worse for a few days after starting treatment, but this is alright. The immune system of the dog is working hard and trying to heal the damaged skin.

Treatments for Generalized Mange

Generalized mange is much more difficult to treat. The veterinarian will prescribe shampoos and dips to help remove the scaly skin and kill the mites. Sometimes, removing what is left of the dog's fur is necessary to have access to all infested areas. The shampoos and dips contain a strong insecticide called amitraz, which kills the mites. Currently, this is the only miticide approved by the FDA for topical use on dogs.

Off-Label Treatments: Ivermectin and Flea/Tick Preventions

There is also an oral medication that can be used to treat dogs with the generalized form. However, it is important to note that the FDA has not officially approved of its use, so any use of the medication is strictly off-label.

Ivermectin is used in heartworm medications, and the use of this drug for treating demodectic mange must be strictly monitored by a veterinarian because of the risks involved. Typically, the dosage starts off low and gradually increases until it reaches a therapeutic level. Once it reaches a therapeutic level, it is maintained until the dog has two negative skin scrapings for mites.

Some of the newer oral flea/tick preventions have shown to be effective in killing demodex mites. This makes treating demodectic mange easier and cheaper for most pet owners. Not to mention the treatment itself is safer as it does not have the side effects of high doses of ivermectin.

Improper Use Can Result in Death

It is extremely important to note that if ivermectin is not used properly, it could result in the death of the dog. For this reason, ivermectin therapy and heartworm medications cannot be used at the same time. A month-long detox is generally needed before the dog can be safely put back onto a heartworm regimen.

Ivermectin Is Dangerous for Certain Breeds

Interestingly enough, most herding dogs, particularly collies (including Border Collies, Shelties, Australian Shepherds, and Old English Sheepdogs) are very susceptible to the side effects of large doses of ivermectin and should never be placed on ivermectin treatment for mange.

Secondary Health Problems

Infections of the skin should be treated with antibiotics as recommended by a veterinarian. It is important to note that some antibiotics and anti-itching medication will not be used since they run the risk of interfering with the dog's immune system.

The same Boston Terrier nearly finished with treatment.

When Will My Dog Get Better?

With all the advances in veterinary medicine, the prognosis for demodectic mange is good. In fact, most vets agree that a dog that has completely overcome the disease should never have a relapse, provided that the dog remains healthy. It is advised that the dog get regular skin scrapings as recommended by your veterinarian to ensure that the mange does not come back.

With proper care, your dog should be able to live a full and healthy life. Most, if not all of the fur should grow back as well. Scar tissue doesn't develop often, but the rest of the dog's body should be covered in fur by the time the dog has been fully treated.

Dogs Can Make a Full Recovery

The main thing to keep in mind about the differences between demodectic mange and sarcoptic mange is that the former is an autoimmune disorder that does not affect dogs with healthy immune systems. It is a nasty disease that can affect dogs at any age, though it is more commonly seen in younger dogs. Thankfully, with all the advances in veterinary medicine, it is possible that a dog can make a full recovery.

Resources

  • Wikipedia
  • VCA Animal Hospitals
  • WebMD for pets
  • Banfield

© 2014 Alex

Alex (author) from Virginia Beach, VA on February 06, 2014:

I did not know that ivermectin was used to treat horses. It makes sense though, its strong stuff. If you look at how much is in heartworm medication and how much is used to treat demodex it is crazy how much more is in demodex treatment.

I know there are still shelters out there that will euthanize dogs that come in with bad cases of demodex. They just can't afford the treatment and can't put the time into treating the dog.

Ann1Az2 from Orange, Texas on February 06, 2014:

I'm so glad they found a successful treatment for the bad kind of mange - about 5 or so years ago, I actually saw a couple of dogs die eventually because of it and it's a miserable skin disease. I believe had they been my dogs, I would have had them euthanized rather than see them suffer. But as you say, the disease came and went, so there were periods where their hair and skin didn't look too bad, so I guess the owners figured they were getting better. I think they also might have thought it was a flea problem, but hey, after so many treatments for fleas, and the skin problem still exists, you would thing some people would get a clue!

Also, you might find it interesting, in case you didn't know, that Ivermectin is a common treatment for worms in horses (in much bigger doses, of course!). It is one of the wormers that kills bots in horses also so when you worm them, it gets rids of several different kinds of worms, as well as bots. Many of the horse wormers do not kill bots so you have to give them two separate medicines.


AGE OF ONSET

Juvenile-Onset

Demodicosis may occur in dogs 18 months of age or younger as a result of an immunocompromised state associated with endoparasitism, malnutrition, or health debilitation. Puppies may also develop demodicosis due to an immature immune system or mite-specific immunoincompetency. 1,3 The increased prevalence in certain breeds indicates a hereditary basis for juvenile-onset demodicosis, particularly for the generalized form. 3

Adult-Onset

In dogs older than 18 months of age, demodicosis may occur as a result of immunosuppression due to drugs (eg, glucocorticoids, ciclosporin, oclacitinib maleate, chemotherapy) or systemic disease (eg, hyperadrenocorticism, hypothyroidism, neoplasia, malnutrition, parasitism). 1,3 Therefore, dogs with adult-onset demodicosis should have a detailed physical examination and full diagnostic workup (Table 1) performed to identify underlying diseases.

Evidence has indicated that successful treatment of an underlying disease may contribute to remission of demodicosis. 1,3 However, up to 56% of dogs with adult-onset canine demodicosis have been reported to have no detectable underlying disease. 2


Mange (Demodex) Symptoms in Dogs and Cats

Mange (demodex) in dogs and cats causes skin problems. Your pet's skin itches—mildly with localized infection and severely with generalized infection. Some pets scratch until they develop bacterial infections along with demodex infections. The hair falls out and bald spots develop. Bald patches, especially around the eyes, mouth, elbows, and front legs are common. The skin may be rough and dry and is referred to as lichenoid. A summary of mange symptoms in dogs are as follows:

There are three forms of mange (demodex), and signs and symptoms depend upon which form your pet develops:

  • Localized
  • Generalized
  • Limited to the feet (pododermatitis)

Localized mange (demodex) occurs in only one area, such as on the ear or the face. A few spots in the local area may be affected. Usually the symptoms are mild and clear up on their own. About 10% of pets with localized mange develop generalized mange.

Generalized mange (demodex) occurs in multiple locations, such as ear, elbow, and stomach, and may progress to cover most of your pet's body, including the feet. Generalized mange occurs in young pets and in adult pets. If it occurs in your adult pet, it suggests your pet has a significant disease or health problem that predisposed him or her to develop widespread mange infection. For example, pets with cancer, hypothyroid disease, allergies, and heartworm infections may develop mange infections.

Mange (demodex) of your pet's feet (paws) can be a localized infection or part of a generalized infection. Pododermatitis is common in dogs with Bulldog genetics.

Positive diagnosis of mange, or demodex mites, is based on finding a skin scraping with the mites. Your veterinarian may make a presumptive diagnosis of demodex infection even though mites are not found on a scraping if your pet has all the symptoms.

Demodex mites live in hair follicles, so the infection is diagnosed by your veterinarian scraping your pet's skin and looking for the mites in scraped material under a microscope. To increase the likelihood that mites are found, your veterinarian will pinch or squeeze your pet's skin gently before taking the scrapping.

A dull tool, such as the back of a scalpel blade is used to scrape your pet's skin. Because mites are hidden in hair follicles, which are nourished by capillaries, a tiny amount of bleeding occurs if the scraping is deep enough. Finding an occasional mite on a skin scraping is normal, but finding many mites diagnoses an infection—especially if the mites are the immature form, which has six legs. A scraping that does not open some capillaries and bleed a tiny amount is not likely to yield results.

Even with excellent scraping techniques, mites can evade detection, so some veterinarians decide to treat pets even though mites were not found on a scraping.

Pets that have positive diagnosis of demodex mites by skin scraping often benefit from several other tests:

  • Fecal exams for worms
  • Blood tests for heartworm infection
  • X-rays for tumors
  • Blood tests for kidney and liver function

These tests are helpful because many pets that develop demodex infections have other serious infections or disease. The tests mentioned above help find these problems which can range from cancer and poorly functioning thyroid glands to heartworm infections and intestinal worms. In pets with high white blood counts, veterinarians look for co-existing fungal infections such as blastomycosis or cryptococcosis.


The immuno-pathological conversions of canine demodicosis

Shanker K. Singh , Umesh Dimri , in Veterinary Parasitology , 2014

1 Introduction

Canine demodicosis is a common but exigent noncontagious parasitic dermatosis caused by overpopulation of the host-specific follicular mites of various Demodex species. Recently it has been validated, that Demodex mite is the normal cutaneous microfauna in most of the healthy dogs ( Ravera et al., 2013 ) and pups acquire the parasite from the bitch during the first days of life ( Greve and Gaffar, 1966 ). Three types of Demodex mites have been described in dogs. Demodex canis mites inhabiting mainly in hair follicle are encountered in most of the clinical cases ( Plant et al., 2011 ), while the long-bodied Demodex injai residing within the sebaceous glands is also implicated ( Desch and Hillier, 2003 Sastre et al., 2013 ). It is more commonly seen in adult onset demodicosis ( Robson et al., 2003 Ordeix et al., 2009 ). A short-bodied Demodex mite resides in the most superficial layer of the epidermis has also been identified in some cases of canine demodicosis ( Chen, 1995 Chesney, 1999 Saridomichelakis et al., 1999 Tamura et al., 2001 ). Recently it was suggested, that the short-bodied Demodex mites could also be D. canis but may inhabit the surface of the epidermis or in the follicular ostiae ( Bourdeau, 2010 ).

Canine demodicosis is differentiated into a localized versus a generalized form. Localized demodicosis has a good prognosis, with the overwhelming majority of cases spontaneously resolving without miticidal treatment ( Scott et al., 2001 ). Generalized demodicosis may be a severe and potentially life-threatening disease ( Mueller et al., 2012 ). Generalized demodicosis is commonly complicated with a secondary bacterial folliculitis and/or furunculosis ( Kuznetsova et al., 2012 ). The dogs with generalized demodicosis showing spontaneous cure is unknown presently, albeit evidence for spontaneous remission in a subset of cases was recently presented ( Bruzinska-Schmidhalter and Nett-Mettler, 2011 ). The number of mites is kept low by a dog's immune system. Despite various studies demonstrating numerous aspects of canine demodicosis immuno-pathological conversions are still matter of discussion to manage the ailment contentedly. The aim of this paper is therefore to review recent investigations establishing the immuno-pathological conversions implicated in the progression as well as susceptibility of canine demodicosis and their possible impact on the management of the disease.

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Demodicosis - Canine Demodex Mite

Demodex mites are microscopic normal inhabitants of dog skin. In a healthy animal, the mites are few in number and do not cause skin problems. In some cases, the mites are able to proliferate excessively, leading to a condition called demodecosis or "mange". Learn about the types of demodectic mange and various treatment options for this skin parasite.


Watch the video: Pet 101: How to Treat Mange (May 2021).