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SARCOPTIC MANGE (SCABIES)

Note for Pet Owners:

This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Sarcoptes scabiei mange mite is transmissible to humans, and so this disease is a Zoonosis. Care needs to be taken when handling animals suspected of having this disease and protective clothing should be worn, for example plastic gloves, during handling. Humans known to have poor immune function or patients being treated with immune-suppressants as well as young children should not be exposed to infected animals.

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Description
Sarcoptic mange (or scabies) is an important skin disease which can affect a variety of species including humans, dogs,  goats,  horses and ponies, pigs, rabbits, sheep, and less commonly cats (rare)

Cause
The cause of this disease is a small (200-400mm) white arthropod mite called Sarcoptes scabiei. Several variants exist including canis which affects dogs primarily. It is a non-seasonal disease in dogs, but the disease occurs most frequently in late winter and early spring in farm animals.

This mite lives permanently in the superficial layers of the skin. It causes intense irritation and itching, although some individuals may not show any signs at all. The female mite lays her eggs in tunnels under the skin. They hatch in 3-8 days and then develop into larvae, nymphs and finally adults. The whole of the lifecycle takes 17-21 days and is completed on the host animal.

The disease is highly contagious and the mite is transmitted most frequently by direct contact with infected animals. However the mites are quite hardy and can survive off the host animal - in a home environment at room temperature for 1-6 days.

Disease occurs as a result of the irritation caused by the presence of the  parasite in the skin, or, most often, due an allergic (hypersensitivity) reaction in the host.

Canine Sarcoptes mites can live on humans for over a week and propagation of the mite on humans has been reported, however most infections clear spontaneously once the infected dog is removed/treated.

Breed Occurrence
There is no breed-specific predilection to develop Sarcoptic mange. Animals that are immune-suppressed are most likely to show evidence of severe disease.

Signs

Clinical signs do not occur for 3-6 weeks after infection with the mite. The primary signs of sarcoptic mange are similar for all species as follows :

  • Intense pruritus (itchiness) with self-trauma - scratching, biting
  • Hairloss
  • Papules
  • Crusts
  • Grazes on the surface of the skin
  • Secondary bacterial infection
  • Thickening of the skin (in chronic cases)
  • Location of skin lesions is widespread  - including
    • Cattle - the neck and sacral region
    • Dogs -  the  abdomen, chest, ears and legs - especially the elbows and hocks.
    • Horses and ponies - the head and neck
    • Pigs - the back
    • Rabbits - the face and ears
    • Sheep and goats - the face and ears
  • Weight loss
  • Enlarged lymph nodes
  • General debilitation
  • Humans
    • Papules - especially on the arms or midriff (trunk)
    • Itchiness

Complications
Bacterial infection may occur as a secondary consequence of Sarcoptic mange.

Diagnosis
Diagnosis is made by examination of deep skin scrapings and identifying mites, eggs or mite feces. Numerous samples are required to be sure to obtain a positive sample and false negative findings are frequently reported because of the "hit-or-miss" nature of sampling. Sometimes mites or their eggs may be found in fecal samples as well.

Histopathology  of skin - best if take an undisturbed papule to section - mites, eggs or mite feces may be found, along with  infiltrations of eosinophils, macrophages, neutrophils, and perivascular aggregates of lymphoid cells.

 

Treatment
Several treatments are available for the treatment of Sarcoptic mange including 

  • The following acaricides which kill the mites:
    • Amitraz
    • Benzyl benzoate
    • Bromocyclen
    • Fipronil
    • Ivermectin
    • Milbemycin
    • Monosulfiram
    • Phosmet
    • Rotenone

Some of these do not have product licenses for use in all species, and some can be toxic eg ivermectin is toxic to Collies. Animals with long haircoats may have to be clipped .

The environment should also be treated in case mites have dropped off into bedding or floor coverings.

  • The itchy pruritus can be controlled using anti-inflammatory drugs eg corticosteroids.
  • Antibiotics may be needed if secondary bacterial infection is present
  • Antiseborrhoeic shampoos are also helpful to cleanse the skin

All animals in a household, stables or farm should be treated.

Prognosis
Good, although thorough treatment of all in-contact animals is necessary to avoid re-infection

 

Updated October 2013