Also known as: Canine Demodicosis, Demodectic Mange
In short
Demodicosis, also known as demodectic mange, is a common canine skin disease caused by an overpopulation of microscopic Demodex mites. Learn how to recognize the signs—such as hair loss and skin redness—how veterinarians diagnose it using deep skin scrapes, and the treatment steps needed to clear the infection.
TL;DR. Demodicosis is a common dog skin condition caused by an overgrowth of microscopic mites, leading to hair loss and skin irritation that requires careful veterinary diagnosis and up to six months of targeted treatment.
Demodex mites are microscopic, normal residents of canine hair follicles that can cause disease when they overpopulate.
Demodicosis, also known as demodectic mange or canine demodicosis, is an inflammatory skin disease in dogs. Unlike other forms of mange, such as sarcoptic mange (scabies), demodicosis is not considered highly contagious between adult dogs. Instead, it is caused by an overpopulation of microscopic mites that are actually normal, healthy residents of your dog's skin.
The primary mite responsible for this condition is Demodex canis, a microscopic, cigar-shaped organism that lives inside the pilosebaceous unit—the anatomical structure consisting of the hair follicle, the sebaceous duct, and the sebaceous gland. Under normal circumstances, these mites live in harmony with the dog's immune system, causing no harm or clinical signs. In fact, they are transmitted from the mother to her puppies during the very first two to three days of nursing.
As noted in a leading veterinary dermatology reference:
"canis , a normal resident of the canine pilosebaceous unit (hair follicle, sebaceous duct, and sebaceous gland), is primarily transmitted from mother to neonate during the first 2 to 3 days of nursing, but adult-to-adult transmission may rarely occur. D. injai , a recently described, large, long-bodied Demodex mite, is also found in the pilosebaceous unit, but its mode of transmission is unknown."
Other mites involved can include Demodex injai, which is a larger, longer-bodied mite, or an unnamed short-bodied Demodex mite that resides in the outermost layer of the skin (the stratum corneum). When the dog's immune system is compromised or fails to keep the mite population in check, the mites multiply rapidly. This massive overpopulation triggers inflammation, leading to hair loss, skin infections, and other dermatological issues.
Veterinarians classify demodicosis in two main ways:
Why does a normal resident mite suddenly become a pathogen? The answer lies in the dog's immune system. In healthy dogs, the immune system naturally limits the reproduction of Demodex mites. However, if the immune system is suppressed or stressed, the mites seize the opportunity to multiply.
In young dogs, localized demodicosis is often triggered by temporary dips in immune function. As a leading veterinary textbook explains:
"Skin lesions occur when there is a localized overpopulation of Demodex canis , a normal commensal inhabitant of canine skin. Demodectic overgrowth is often associated with a predisposing factor such as endoparasitism, poor nutrition, immunosuppressive drug therapy, or transient stress (e. g. , estrus, pregnancy, surgery, boarding)."
In adult dogs, the sudden onset of generalized demodicosis is a major red flag. It usually indicates a serious underlying medical condition that is suppressing the immune system. Common culprits include hormonal disorders (such as Cushing's disease or hypothyroidism), underlying cancers, or the administration of immunosuppressive drugs (like steroids or chemotherapy).
Additionally, genetics play a significant role. Certain breeds are genetically predisposed to developing demodicosis, suggesting an inherited immune defect that prevents them from controlling the mite population. These breeds include the Rat Terrier, English Bulldog, and Chinese Shar-Pei.
The clinical signs of demodicosis can vary widely depending on whether the disease is localized or generalized, and whether secondary bacterial infections have developed.
As noted in veterinary literature:
"Usually, patchy, regional, multifocal, or diffuse alopecia is observed with variable erythema, silvery grayish scaling, papules, or pruritus. Affected skin may become lichenified, hyperpigmented, pustular, eroded, crusted, or ulcerated from secondary superficial or deep pyoderma. Lesions can be anywhere on the body, including the feet. Pododemodicosis is characterized by any combination of interdigital lesions."
Pododemodicosis (demodicosis of the feet) is particularly challenging. It can cause severe swelling, pain, limping, and deep, draining tracts between the toes that are highly resistant to treatment.
Patchy hair loss (alopecia) around the eyes and face is a classic clinical sign of demodicosis.
If your dog is showing signs of hair loss or skin irritation, your veterinarian will perform specific diagnostic tests to confirm the presence of Demodex mites and rule out other skin conditions like ringworm or sarcoptic mange.
As explained in a clinical guide:
"This ensures that the material collected comes from deep enough within the skin to allow the collection of follicular Demodex mites. Most people also squeeze (pinch) the skin to express mites from deep within the follicles into a more superficial area, so that they may be collected more easily. If scraping fails to provide a small amount of blood, then the mites may have been left in the follicle..."
The collected material is then mixed with mineral oil and examined under a microscope to look for the characteristic cigar-shaped mites, their eggs, and larvae.
A deep skin scrape, performed by gently pinching the skin and scraping until capillary bleeding occurs, is the gold standard for diagnosing demodicosis.
Treating demodicosis depends heavily on whether the disease is localized or generalized.
Localized Demodicosis: Many cases of localized juvenile-onset demodicosis are self-limiting and resolve on their own within several weeks as the puppy's immune system matures. Your vet may choose to monitor the lesions or prescribe a mild topical treatment. It is crucial to address any underlying predisposing factors, such as treating internal parasites (endoparasitism), improving nutrition, or reducing stress.
Generalized Demodicosis: Generalized demodicosis is a serious condition that requires aggressive, long-term therapy. Treatment typically involves a combination of antiparasitic medications to kill the mites and antibiotics to treat any secondary bacterial infections.
The Golden Rule of Treatment Duration: Regardless of the medication used, treatment for generalized demodicosis is a marathon, not a sprint. It can take up to six months to completely clear the infection. A common and costly mistake owners make is stopping treatment as soon as the dog's hair grows back and the skin looks healthy. Premature discontinuation of treatment is the leading cause of relapse. Your vet will perform regular skin scrapes every 2 to 4 weeks. Treatment must continue past clinical resolution and should only be stopped after obtaining at least two consecutive negative skin scrapes spaced several weeks apart.
The prognosis for dogs with demodicosis is generally good, provided the owner is committed to aggressive and consistent treatment.
For localized juvenile-onset demodicosis, the prognosis is excellent, with the vast majority of puppies recovering fully and never experiencing a recurrence.
For generalized juvenile-onset demodicosis, the prognosis is also good to excellent with modern antiparasitic therapies, though it requires up to six months of diligent treatment and regular veterinary follow-ups.
For adult-onset generalized demodicosis, the prognosis is more guarded and depends heavily on the underlying cause. If the primary disease suppressing the immune system (such as Cushing's disease or cancer) can be identified and successfully managed, the demodicosis can usually be cleared. However, if the underlying immune suppression cannot be resolved, the dog may require lifelong management to keep the mite population under control.
Because Demodex mites are normal, commensal inhabitants of canine skin passed from mother to puppy during the first days of life, you cannot prevent your dog from carrying the mites. However, you can take steps to prevent the mites from overpopulating and causing disease:
You should schedule a veterinary appointment if you notice any signs of hair loss, scaling, or redness on your dog's skin. Early intervention is key to preventing localized demodicosis from progressing to a more severe, generalized form.
You must seek immediate veterinary attention if your dog exhibits any of the following red-flag signs of a severe, systemic infection:
If you own a Rat Terrier, English Bulldog, or Chinese Shar-Pei, you should be extra vigilant. These breeds are genetically predisposed to demodicosis.
In the Chinese Shar-Pei, the breed's characteristic thick, folded skin can make diagnosing demodicosis particularly challenging. The mites can hide deep within the thick dermal layers, meaning standard skin scrapes may occasionally yield false-negative results. If your Shar-Pei is showing signs of skin disease but skin scrapes are negative, your vet may recommend a skin biopsy to accurately locate the mites and begin appropriate treatment.
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
Demodicosis, also known as demodectic mange, is a common canine skin disease caused by an overpopulation of microscopic Demodex mites. Learn how to recognize the signs—such as hair loss and skin redness—how veterinarians diagnose it using deep skin scrapes, and the treatment steps needed to clear the infection.
Alopecia、Erythema、Scaling、Comedones、Greasy seborrhea、Hyperpigmentation、Lichenification、Papules
Deep skin scrape、Hair-plucks、Skin biopsy
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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