Demodectic mange occurs when large numbers of Demodex mites infest a dog’s skin. When small in number, Demodex mites are considered a normal part of the canine biome.
• When the mite population grows to a level where it results in mange, it is indicative of an underlying issue with the immune system, especially in dogs over the age of 2
• Symptoms include hair loss and crusting of the skin that is usually not itchy
• Diagnosis includes a physical examination, skin scraping, and hair plucking
• Treatment of generalized demodicosis involves long-term anti-parasitic therapy
• A dog presenting with secondary bacterial skin infections is treated with antibiotics
• Prognosis depends on the severity of the underlying condition that caused an immune disturbance and allowed mite proliferation
Demodectic mange is a common condition in dogs. Demodex mites are a normal part of canine skin fauna. Demodicosis (mange) occurs when the animal’s immune system is not able to keep the mite population under control.
It generally affects young puppies under the age of one, as well as geriatric and immunosuppressed dogs. In most cases, young dogs suffering from localized demodicosis recover without treatment.
Demodicosis in adult dogs is a sentinel for immunosuppressive issues, and as such prompt veterinary attention is warranted.
Note: Demodicosis is not to be confused with sarcoptic mange (scabies). Demodex mites live in the animal’s hair follicles and may not cause any itchiness, in contrast with Sarcoptes mites that live under the animal’s skin and cause extreme itchiness.
Demodicosis can be categorized according to where symptoms are observed on the body and age of onset.
Localized: Localized demodicosis is characterized by isolated hairless patches of skin, affecting no more than two body regions. Localized demodicosis is a common skin condition in puppies, and the majority of cases resolve without treatment. 90% of cases resolve on their own, 10% progress into generalized demodicosis.
Generalized: Generalized demodicosis is characterized by extensive bald patches. If left untreated, it can progress and affect the entirety of the animal’s body. Dogs presenting with generalized demodicosis commonly have secondary bacterial skin infections that cause itchiness.
Juvenile Onset: Juvenile onset demodicosis is the most common form of the condition. As the dog grows older, its immune system fully develops and the animal's body is able to control the mite population. Up to 50% of affected puppies recover without treatment.
Adult Onset: Adult-onset demodicosis is rare. If a dog over the age of 2 presents with demodicosis, prompt medical attention is warranted as the condition indicates the presence of potentially life-threatening underlying conditions such as liver disease, kidney disease, immunosuppressive disorders, or cancer.
Demodicosis is caused by the excessive presence of Demodex mites (tiny eight-legged organisms) in the animal’s hair follicles. Three different kinds of Demodex mites can cause demodicosis:
• Demodex canis: the most common cause of Demodicosis in dogs • Demodex cornei • Demodex injai
Conditions that affect the immune system, such as cancer, liver or kidney disease, metabolic diseases, or immunosuppressive disorders contribute to the overproliferation of mites on the skin.
Main symptoms of demodicosis include:
• Alopecia (hair loss) • Crusting • Skin sores or scrapes
• Symptoms associated with secondary skin infections such as itchiness, foul odor, oozing or weepy skin, and redness of the skin
Diagnosis of Demodicosis is generally straightforward.
A dog presenting with symptoms of demodicosis of general undergoes the following diagnostics:
• Physical examination • Skin scraping and hair plucking • Skin biopsy
Typically mites or their eggs are easily identified under the microscope, however in some cases the skin scraping may be negative. Dogs showing symptoms associated with demodicosis may be presumed to have the condition and treatment may proceed despite a negative skin scraping.
Once diagnosed, treatment depends on the kind of demodicosis.
Localized Demodicosis: Generally resolves spontaneously, but treatment with topical ointments may be indicated. Note: always consult a veterinarian before administering topical medication to animals. Many topical treatments are toxic to pets, especially cats.
Generalized Demodicosis: Requires long-term, aggressive therapy. While treatment of the mite infestation is occurring, treatment of the underlying condition impacting the immune system is necessary to prevent recurrence and further development of symptoms. Treatment of the mange usually involves antiparasitic treatment for the mites and antibiotics for any secondary skin infections.
Juvenile-onset demodicosis generally has a good prognosis, with up to 50% of cases resolving without treatment. Generalized adult-onset demodicosis can vary from moderate to severe. Whichever underlying condition is impacting the immune system and contributing to uncontrollable mite infestations has its own treatment and prognosis, which directly impacts the overall prognosis of mange in these cases.
Recommended treatment protocols must be followed closely, as recurrence of demodicosis can occur when the anti-parasite therapy is discontinued before all mites have been eradicated.
Demodicosis is not contagious, as all dogs naturally harbor the mite as part of their skin biome. Only dogs with an underlying immune system disorder develop symptoms of mange. Keeping up to date with vaccinations and annual veterinarian check-ups can help increase the animal’s general health and identify underlying conditions early, which usually helps improve long term outcomes.
Demodicosis is a common skin condition in puppies, and rare in older dogs.
• Anti-parasitic therapy • Antibiotic therapy • Treatment of underlying immune system condition
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