When someone refers to a dog as "mangy" it conjures up a specific image, but what exactly is mange and what does it mean for you and your dog?
Mange is the common term for a skin infection from microscopic mites, either the Scabies mite or the Demodex mite. While these two mites are often grouped into the same category of mange they are quite different in their clinical presentation and treatment.
Demodectic Mange in Dogs
Demodicosis is cause by the demodex canis mite. It is most prevalent in younger dogs and is not contagious to people or other animals. This mite normally lives on a dog's skin in small numbers without issue. They are transferred from mom to puppy during nursing in the first few days of life. However, once a puppies’ immune system kicks in they should be able to manage the exposure to mites without ever developing clinical signs.
There are two other routes that an infection can take that are dependent on the number of mites present and the individual dog 's immune system.
If a puppy is infected with a moderate to large amount of mites they can develop localized demodex infection which resolves without treatment in a majority of cases.
Clinical signs associated with Demodectic mange in dogs include:
- Patchy hair loss
- Redness or crusting of the skin
- Occasionally mild to moderate itching
Some puppies whose immune system may not be as robust can develop generalized Demodectic mange in dogs, which is a much more severe disease process. In these cases there are several areas of hair loss with an accompanying bacterial skin infection presenting as crusty skin with discharge, scaling and redness. This can also occur in puppies that have a specific hereditary deficiency in their immune system.
Dogs with generalized Demodex are usually uncomfortable and can be itchy. They may be feverish as a secondary to the bacterial skin infections. If left untreated, this can progress to a systemic infection resulting in death. In adult dogs presenting with demodex infections, one must question the effectiveness of that dog's immune system and look for underlying diseases.
Diagnosis and Treatment of Demodectic Mange in Dogs
Diagnosis of Demodex is very straightforward and accomplished with a deep skin scrape or plucking hair to collect the mites from their residence within the hair follicles. Once a diagnosis of generalized demodicosis is made, treatment is started with the goals of killing the mites and treating any secondary bacterial infections. Secondary infections are treated with oral antibiotics. Topical benzoyl peroxide shampoos are an effective adjuvant treatment by flushing the mites from the follicles.
There are several antidemodetic medications that are available. The only FDA approved treatment is topical amitraz (Mitaban) dips which has shown 60-80% effectiveness in treating demodex. There are several potential side effects such as lethargy, diarrhea, low heart rate and skin irritation. Ivermectin is the most commonly use treatment option but must be used with caution in herding breeds that have a genetic sensitivity to ivermectin. There is a DNA test that can be performed in herding breeds to indicate if they can tolerate treatment with ivermectin. Side effects of ivermectin include lethargy, tremors, disorientation, stumbling, blindness and other neurologic issues. These are very rare at an appropriate dose in non-herding breeds and individuals that test negative to the genetic mutation.
If Ivermectin is not an option then daily milbemycin (Interceptor) is a possibility, albeit a very expensive one. Treatment with both ivermectin and milbemycin is 80-85% effective and usually lasts 2-4 months. Dogs that develop generalized demodicosis should be spayed or neutered to prevent propagation of the hereditary skin deficiency that possibly contributed to the infection.
Scabies in Dogs
Sarcoptic mange is caused by the Sarcoptic scabiei mite. While this mite prefers dogs it can be transmitted to people. This mite is seen in all ages of dogs and can also survive in the environment from 24 hours to 3 weeks. The hallmark of a scabies infection is intense itching; dogs infected with this mite are insanely itchy all the time. Like demodex, they can develop patchy hair loss and secondary skin infection but itching is the main thing to look for.
Diagnosis and Treatment of Scabies in Dogs
There are many ways to diagnose scabies. The most common test is a superficial skin scrape in which a blade is used to try and collect mites that can be identified under the microscope. Unfortunately, the scabies mite can be quite elusive and is not always captured with a superficial skin scrape. Thus, if your dog is very itchy, it is reasonable to treat empirically for scabies to see if this helps resolve the clinical signs. If there is an underlying secondary bacterial or yeast infection present, this may be contributing to the itchiness and will also require treatment.
Usually scabies in dogs is straightforward to treat. There are several topical and oral medications available. Since the mite can live in the environment, it is also best to wash all bedding that your dog was using to eliminate any lingering critters.
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