What is mange, and how do I know if my dog has it?

Mange is a skin disease caused by microscopic mites. The word covers several different conditions, and the type matters, because they spread differently and need different treatment. This guide explains the main types so you know what to look for and when to call your vet.

What causes mange?

Mange is caused by mites, tiny relatives of spiders that live on or in the skin. Two types cause most cases in dogs: Sarcoptes scabiei, which causes sarcoptic mange, and Demodex mites, which cause demodectic mange (also called demodicosis).

Sarcoptic mange (canine scabies)

How dogs catch it

Sarcoptic mites burrow into the skin. PDSA explains that sarcoptic mange is highly contagious and most commonly caught from infected dogs and foxes. It spreads by direct contact, and can also spread through shared bedding, brushes and towels.

Signs to look for

• Intense itching that often gets worse over time
• Red, crusty skin and hair loss
• Changes that start on the ear flaps, elbows and hocks (ankles), then spread
• Sores and skin infections from scratching

Left untreated, sarcoptic mange can make a dog very unwell.

Can people catch it?

PDSA notes that people can't catch human scabies from a dog with mange. The MSD Veterinary Manual adds that people in close contact with an affected dog can get a temporary itchy rash from the dog's mites. If you develop an itchy rash while your dog has mange, speak to your GP.

Demodectic mange (demodicosis)

Why it happens

Demodex mites live in the hair follicles of most dogs in small numbers and normally cause no problems. Puppies pick them up from their mother in the first days of life. Demodicosis develops when the mites multiply out of control, usually because the immune system isn't keeping them in check.

Forms of demodectic mange

• Localised: one or a few small patches of hair loss, often on the face or legs, usually in dogs under a year old. Many of these cases clear up on their own as the dog matures, but a vet should still check them.
• Generalised: larger or many affected areas, often with redness, scaling and infection. It needs veterinary treatment.
• Adult-onset: demodicosis that starts in an adult dog can be linked to an underlying illness or medicines that affect the immune system, so your vet may look for a cause.

Demodectic mange isn't usually passed between healthy adult dogs.

Other mites that affect dogs

• Ear mites (Otodectes cynotis) cause head shaking, ear scratching and dark brown wax. They spread between cats and dogs, so all pets in the home may need treatment.
• Cheyletiella ("walking dandruff") causes heavy scaling along the back. It is very contagious and can also affect people.
• Harvest mites are seasonal larvae picked up outdoors, usually in late summer and autumn. They appear as tiny orange dots, often between the toes, and cause itching. They don't spread from dog to dog.

How vets diagnose mange

Your vet will examine your dog and usually take skin scrapings or hair samples to look for mites under a microscope. Sarcoptic mites can be hard to find, so your vet may recommend treatment based on the signs, even if a scraping is negative.

How mange is treated

Treatment depends on the type of mange, so always follow your vet's advice. PDSA explains that sarcoptic mange is usually treated with a prescribed spot-on, tablet or shampoo, often with two or three treatments a few weeks apart. All dogs in close contact need treating too. Your vet may also recommend washing bedding and grooming equipment. Dogs with infected or very sore skin may need extra medicines.

Generalised demodectic mange can take longer to treat, and your vet will usually recheck skin samples until the mites are gone.

Don't use over-the-counter or home remedies for suspected mange. They can delay the right treatment, and some products are toxic to pets.