Scabies (Sarcoptic Mange)
Scabies, also known as sarcoptic mange, is sudden, localized, very intense itching (pruritis) caused by Sarcoptes mites. The mite burrows into the skin to lay its eggs. After hatching, the nymphs and larvae feed on the skin. Intense pruritis is caused by the burrowing and hypersensitivity (allergic) reaction to the secretions of the mites. Scabies is highly contagious among dogs and cats and can be transmitted to humans.
Areas commonly affected include the abdomen, chest, legs, and ears. Symptoms include the following:
- Ear margin lesions
- Intense pruritis (itching)
- Papules (raised bumps) with thick yellow crusts
Scabies is difficult to diagnose based on microscopic examination of skin scrapings (these are positive in only 20 percent of cases). A diagnostic test known as the pinnal-pedal reflex is more helpful (a 75–90 percent accuracy rate). This test involves rubbing the ear between the thumb and forefinger causing the dog to scratch with the hind leg on that same side of the body.
The feces may contain mites or mite eggs. Sometimes, the easiest way to diagnose scabies is to try a prescribed scabicide (something that kills the scabies mites) and see if it reduces symptoms.
Treatment may include a scabicidal dip. The entire animal is rinsed with an amatraz (Mitaban), lime sulfur (LymDip), or organophosphate (Paramite) solution.
Amitraz is applied every 1 to 2 weeks for three treatments. Amitraz dips can be toxic and are usually administered by a trained veterinary technician; pet owners should be aware of all safety precautions. Amitraz kills ticks and mites by affecting the nervous system.
Lime sulfur should be applied weekly until 2 weeks after all clinical signs of infestation have disappeared; most cases require 6 weeks of treatment, though it may take longer. This is considered the safest treatment for very young or debilitated pets.
A paramite dip is applied every 2 weeks for at least three treatments; most cases require more than three dips. The pet should not get wet between treatments.
Other treatments include ivermectin and selamectrin. Ivermectin is highly effective and may be injected every 2 weeks for two to three treatments. Ivermectin should not be used in collies, shelties, other herding breeds, dogs with heartworm, or puppies younger than 6 months of age. Selamectrin may be applied topically two times, 1 month apart (some animals may be cured with the first application).
The animal's environment should be thoroughly cleaned and treated; Sarcopes mites can survive in the environment for as long as 3 weeks.
All dogs that come in contact with the infected dog should be treated. Animals that don't show signs of scabies may be asymptomatic carriers and could cause recurring infestations.