Canine scabies can affect any dog regardless of age, breed, or coat type. It's rare for only one dog in a multi-pet home to exhibit clinical signs. Unlike demodectic mange that is not contagious, sarcoptic mange is so contagious that usually if one animal in a household is affected, all animals are infected.
Sarcoptic Mange Life Cycle
Sarcoptic mange, also known as canine scabies, is a parasite disease caused by Sarcoptes scabei var. canis, a circular short-legged microscopic mite that burrows into the skin.
After burrowing, the female mite forms a tunnel and lays three to five eggs daily. Larvae emerge within another three to eight days, and after hatching, those that migrate across the surface of the host animal's skin often will die. But most larvae stay in the tunnel or its extensions (called "molting pockets") where they develop into nymphs.
Some nymphs stay in the original tunnels and molting pockets, while others burrow and form new tunnels. A few wander onto the skin surface to feed and mate, where the potential for transmission to yet another host becomes possible. The next molt produces adult male and female mites. The cycle from egg to adult takes 17 to 21 days. Mites have an average life span of three to four weeks.
How Puppies Catch Canine Scabies
Mites carrying canine scabies are usually transmitted by direct dog-to-dog contact. The mite lives out its entire life cycle on the dog, but mites can survive up to 48 hours off a host. This means a puppy could pick up the mites simply by sleeping on a blanket used by an infected dog, or by sharing grooming tools like brushes.
Most dogs develop symptoms about three weeks after exposure. The mite prefers sparsely-furred areas of the body, like the hock, elbow, area surrounding the eyes and muzzle, stomach, ear flap and the root of the tail.
Signs of Sarcoptic Mange
Burrowing mites produce intense itching which prompts the infected puppy to chew, scratch, and rub the affected areas. The scratch reflex in affected pups can be easily stimulated; by merely manipulating the pinnae (ear flap) the pup will often kick a hind leg in reaction.
Excessive scratching results in skin inflammation, and red papules and sores and secondary infections often develop. Crusts form on the surface of the affected skin, and as the disease intensifies, the skin thickens.
Untreated dogs will have dry, deeply wrinkled and thick skin. Damaged skin causes loosened hair to fall out, and the sparseness of hair, in turn, provides the mite with an even better environment in which to proliferate.
Diagnosis and Treatment
Left untreated, the disease may continue for months to years. Victims with advanced mite infestation become irritable and are restless, and subsequently, begin to lose weight. Diagnosis is based on signs of disease, and on finding the mite in microscopic examination of skin scrapings.
Treating Puppies with Mange
Scabies can be difficult to diagnose because the mites can be hard to find; only about 30 percent of canine scabies cases actually locate a mite in skin scrapings. For this reason, the condition may be confused with seborrhea, flea allergy, or other skin conditions.
Treatment is often the best diagnosis. Dogs that respond favorably to therapy are deemed to have scabies. Treatment consists of medication to kill the mites and additional therapies to help with itching and secondary skin infections. There are topical, oral, and injectable miticide treatment options. If a topical medication is selected, clipping the puppy’s fur is recommended.
Several effective scabicides are available from a veterinarian. Multiple treatments over several weeks are generally needed for satisfactory results. Ivermectin, which is the active ingredient in some heartworm preventatives, is also effective against sarcoptic mange. Ivermectin should be avoided in collies, shelties, and related breeds due to risk of toxicity and adverse reaction.
Secondary infections generally respond to the medicated shampoos and elizabethan collars to prevent further self-trauma, but some cases require oral antibiotics. In severe cases of sarcoptic infection, use of concurrent therapy may be warranted. A high-quality, well-balanced puppy diet for affected pups is important as well.
Because the condition is so contagious, all dogs and cats in contact with the affected animal should be treated. Some puppies may be carriers of the mite, without ever showing clinical signs themselves.
How Puppy Mange Affects People
Canine scabies almost exclusively affects dogs, but can also cause skin disease in cats or in people. It most commonly affects owners who allow the pup to sleep in their bed or who hold the pup a great deal.
In people, the mite causes itching and inflammation, and prolonged exposure may produce sores. However, the mite does not reproduce on people and curing the puppy typically also cures the owner within seven to 28 days following treatment of the affected dog.
Once cured, dogs are not immune to reinfection. Part of the treatment should include disinfection of the dog's bedding, grooming tools, collar, and carriers, to prevent reinfestation. Reduced exposure to other dogs and vigorous treatment at the earliest warning will keep your puppy free of this disease.