Mange in dogs (sarcoptic and demodectic)

Symptoms an owner can spot at home

• Sarcoptic: relentless scratching that does not pause for distraction, often worse at night
• Sarcoptic: crusting and hair loss on ear margins, elbows, hocks, and belly first
• Sarcoptic: a scratch reflex when the ear margin is rubbed
• Demodectic: patchy hair loss, commonly around the eyes, muzzle, and forelimbs, with little or no itch
• Demodectic: greasy, thickened, or reddened skin, with itch appearing only once secondary infection sets in

When to see a vet

• Any sudden, severe, non-stop itch, sarcoptic mange is a same-week visit, not a wait-and-see
• Hair loss spreading over more than one body region, or affecting the whole body
• Open sores, crusting with odour, or pus, secondary pyoderma needs treatment alongside the mites
• People in the household developing itchy papular rashes on forearms or waistline
• Demodicosis appearing for the first time in an adult dog, this can flag an underlying endocrine or immune disease

What it is

Sarcoptic mange is caused by Sarcoptes scabiei var. canis, a burrowing mite that tunnels into the outer skin layer. The itch is a hypersensitivity reaction, not simple mechanical irritation, which is why a handful of mites can drive an extreme response. It transmits by direct dog-to-dog contact and via recently contaminated bedding and grooming equipment, and it is zoonotic: humans can develop a self-limiting itchy rash, though the mite cannot complete its life cycle on people.

Demodectic mange is a different problem entirely. Demodex canis lives in the hair follicles of virtually all normal dogs, transferred from the dam in the first days of life. Disease occurs only when mite numbers overgrow, which happens with an immature immune system in puppies (localised, usually self-limiting) or with immune suppression, endocrine disease, or heavy parasite burden in adults (generalised, and a marker to investigate). It is not contagious between adult dogs.

How vets diagnose it

Deep skin scrapings, squeezed to express follicular contents, are the standard test. Demodex is found readily this way. Sarcoptes is notoriously hard to find, mites are recovered in a minority of true cases, so a negative scrape does not exclude scabies. Vets often diagnose it by response to a targeted acaricidal trial, backed by the clinical picture and contact history. Trichograms and, in stubborn cases, skin biopsy fill in the remaining gaps.

The differential list matters: allergic skin disease, flea allergy dermatitis, and secondary bacterial or yeast infection all produce overlapping pictures, and more than one can run at once.

Treatment overview

This is editorial overview, not a treatment plan; your vet builds the plan. Modern management for both forms centres on prescription isoxazoline-class parasiticides, which have largely displaced older dips. Sarcoptic cases require every in-contact dog to be treated simultaneously, not just the itchy one. Generalised demodicosis is treated to two consecutive negative skin scrapings, not to the point where the coat merely looks better.

Secondary bacterial infection is treated in parallel, and adult-onset generalised demodicosis triggers a workup for the underlying cause. Over-the-counter sulphur or benzoyl peroxide products can support the skin surface but do not clear either mite; treating on your own delays the diagnosis that determines which disease you actually have.

What owners can do

• Get the diagnosis before the purchase. Sarcoptic and demodectic mange look similar from the sofa and are managed differently.
• Launder or replace soft goods during a sarcoptic case. Bedding, collars, and harness padding hold mites for a short window; hot wash and full dry, or swap them out.
• Choose washable, machine-dryable beds without deep sewn baffles, so a weekly decontamination cycle is realistic rather than aspirational.
• Use non-porous grooming tools that can be disinfected between uses, and stop sharing brushes across dogs during an active case.
• Support the skin barrier while the acaricide works: fragrance-free shampoo and vet-directed omega-3 supplementation ease surface inflammation.
• Keep every in-contact dog on the same treatment schedule; one untreated housemate reseeds the household.