Demodicosis in Dogs: Localised vs. Generalised, Signs & Treatment

Demodicosis (demodectic mange / "follicular mange") is a skin disease caused by the overgrowth of Demodex canis — a microscopic mite that naturally lives in the hair follicles of all dogs. It is not transmitted to people or healthy dogs through ordinary contact.

What Is Demodex canis?: Demodex canis inhabits the hair follicles and sebaceous glands of dogs from birth. Most dogs control mite numbers naturally with no symptoms. When immune function is weakened or abnormal, however, the mites may multiply excessively and trigger disease.

Two Types of Demodicosis

Localised: Most common in dogs under 18 months; presents as five or fewer small areas of hair loss, typically on the face or forelegs. Most cases resolve on their own under veterinary supervision.

Generalised: More than five lesions, or widespread involvement across the body — requires active treatment. Can occur in young or adult dogs. In adult-onset cases, an underlying systemic disease causing immune suppression should be investigated.

Signs to Watch For

• Patchy hair loss, typically starting on the face or forelegs
• Redness, scaling, or comedones (blackheads)
• In severe cases: pain, pustules, or bleeding (with deep infection)

Diagnosis: The primary tool is deep skin scraping — examining the sample under a microscope to find mites, developmental stages, and quantities, which helps assess treatment response. Regular follow-up appointments with repeat scraping are therefore essential. Your vet will also check for concurrent bacterial infection, as deep pyoderma commonly accompanies severe demodicosis.

Treatment: Your vet will select the appropriate anti-mite medication based on age, weight, and health status. Mild localised cases may need monitoring only. Any secondary bacterial infection must be treated separately. Continue medication until your vet advises stopping — regrowth of coat does not mean the mites are under control. Inform your vet of any history of seizures and all current medications before starting treatment.

Home Care: Continue all prescribed medications without stopping on your own; attend every scheduled follow-up for repeat skin scraping; avoid applying any unprescribed insecticides.

Prognosis: Most dogs recover fully, though severe cases may require months of ongoing management. Demodicosis is not contagious to people or healthy dogs through everyday contact.

Contact Thonglor Pet Hospital

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