Canine Demodicosis: Welfare Implications of a Common Skin Disease

Demodicosis is a skin disease in dogs caused by proliferation of Demodex mites. It ranges from localised, self-limiting cases to severe, generalised disease requiring intensive treatment.

Key Facts

Demodex canis mites are normal commensals of dog skin, present in small numbers in most healthy dogs.
Disease occurs when mites proliferate beyond normal levels, typically due to immune suppression or genetic predisposition.
Juvenile-onset demodicosis occurs in dogs under 18 months, often resolving spontaneously; adult-onset disease typically indicates underlying immunosuppression.
Generalised demodicosis causes extensive hair loss, crusting, pustules, secondary bacterial infections, and severe pruritus.
Treatment includes isoxazoline class parasiticides (afoxolaner, fluralaner, sarolaner) which have transformed treatment outcomes.
Secondary pyoderma must be treated concurrently with antiparasitic therapy for effective management.
Adult-onset demodicosis warrants investigation for underlying causes: hypothyroidism, hyperadrenocorticism, malignancy, or immunosuppressive therapy.
Breed predispositions include Bulldogs, Boxers, Shar Peis, and Staffordshire Bull Terriers.

Welfare Considerations

Generalised demodicosis is one of the most uncomfortable skin conditions a dog can experience. Secondary bacterial infection causes painful, itchy skin lesions; the extensive hair loss exposes skin to UV radiation and environmental irritants; and without effective treatment, the disease is progressive and debilitating. Historically, demodicosis was extremely difficult to treat and required prolonged, labour-intensive treatments (weekly amitraz dips) with significant side effects. The introduction of isoxazoline antiparasitic drugs has dramatically improved treatment outcomes, making resolution of even severe cases achievable within a few months. Welfare is maximised by early recognition, prompt treatment, concurrent management of secondary infections, and investigation of predisposing causes in adult-onset cases.

What You Can Do

Seek veterinary assessment promptly if your dog develops hair loss, crusting, or skin thickening.
Complete the full course of treatment for demodicosis even if improvement is rapid.
Investigate underlying immunosuppressive conditions in dogs over 18 months that develop demodicosis.
Support breeding organisations that discourage breeding from dogs with hereditary immunosuppression.
Be aware that dogs with a history of juvenile demodicosis may have a genetic predisposition to discuss with your vet before breeding.
Maintain regular veterinary health checks for all dogs to detect skin conditions early.