Sarcoptes scabiei

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Sarcoptes scabiei (Linnaeus, 1758) Latreille, 1802

(Figure 5-33)

Sarcoptesscabiei is not commonly reported from cats. The adults of Sarcoptes are larger than those of Notoedres, and te female has large triangular spines on the surface of its body (Fig. 5-33) Work by Arlian et al. (1988) has reinforced the long-held belief that the isolates of this species from different hosts tend to be host specific. Others have suggested that hosts that are natural hosts to a species of Notoedres tend to be refractory to infection with species of Sarcoptes. There have been three reports of sarcoptic mange in cats.

Linquist and Cash (1973) reported that an 8- to 10-week-old kitten had extensive hair loss over the ears, head, neck, abdomen, and tail with the skin on the abdomen being thickened, scaly, and wrinkled. The kitten had been owned by two families. The first family (husband, wife, and two visiting daughters) kept the kitten a week and then gave it to a second family (a father and daughter). The second family noticed the hair loss and brought the kitten to the veterinary clinic. Four of the six family members in contact with the cats developed lesions. The father isn the second family developed scabby lesions on his back and on the bridge of his nose; the kitten would sometimes curl up on his bare back while he was sleeping on the sofa. He treated himself with an over-the counter ectoparasiticid preparation (pyrethrins and piperonyl butoxide). The daughter developed similar lesions on her abdomen (where the kitten would sometimes rest while she read), and she also was treated with the same over-the-counter product. The two daughters in the first family also developed skin lesions two weeks after having the kitten; the lesions were treated with either 1% benzene hexachloride or a pyrethrin and piperonyl butoxide preparation. Infections with Sarcoptes scabie were never actually identified in any family member and the two dogs owned by the first family showed no evidence of scabies.

Bussieras (1984) reportred on skin lesions in a 15-month-old Persian cat with a history of pruriginous dermatitis. Examination of the cat revealed Microsporum canis and numerous mites identified as Sarcoptes scabiei. Again, lesions were also noted on the owner. The cat was treated by the weekly application of 0.025% amitraz for five weeks and with griseofulvin and enilconazole for the Microsporumcanis. It was suspected that the cat had an underlying abnormal susceptibility to dermatologic pathogens which remained undiagnosed.

Hawkins et al. (1987) reported on a case of Sarcoptesscabiei infestation in an adult cat that had lived in a household for six years after being taken in as a stray. The owner had seven other cats, several of which had been diagnosed as positive for feline leukemia virus. The cat when admitted for examination was recumbent, unresponsive, 8% to 10% dehydrated, and emaciated. The lesions consisted of a 1 cm thick, tightly adhering, yellowish gray, exudative crust on the tail, caudal aspect of the thighs, and on all feet. Paronychia and dystrophic nails were also observed. The lesions had worsened over a twelve month period, but the depression was of acute onset. This cat was found to be negative feline leukemia virus, and no mites were discovered in an examination of a single skin scraping. The was then placed on a regimen of oral prednisolone (2 mg/.kg of body weight every 12 hours). Within a few days of the cats discharge, a veterinary student and a technician who had handled the cat developed pruritic cutaneous papules that lasted for 10 to 14 days. The owner was then questioned, and it was found that he also had had pruritic skin lesions for an extended period. The cat was then readmitted, and additional skin scrapings revealed numerous mites identified as Sarcoptesscabiei. A skin biopsy taken at this time revealed orthokeratotic and parakeratotic hyperkeratosis and irregular epidermal hyperplasia., and mites were observed in the biopsy. The administration of prednisolone was discontinued, however, after a second traumatic lime-sulfur dip, the cat awas readmitted again severely distressed and unfortunately this time it did not respond to supportive therapy and died.

Currently, ivermectin (200 g per kg body weight) would probably be the treatment of choice for sarcoptic mange in cats. There is every reason to believe that the success of this compound in treating scabies in other hosts and in treating notoedric mange that it would be highly efficacious in the treatment of feline scabies. It is important to note that in all three cases of feline infestations with Sarcoptesscabiei, there was apparent transmission of the mite to humans who came in contact with the infested cat. Thus, it appears much more important to confine cats that are infested with Sarcoptesscabiei after treatment than would be needed in cases of notoedric mange. It would also suggest that when cases of suspected notoedric mange are found transmitted to owners or others individuals that have handled the cats that the identification of the species of mite involved is important because of the much greater risk of contamination that accompanies infestation with Sarcoptesscabiei in the feline host.

REFERENCES:

Arlian LG, Vyszenski-Mohert DL, Cordova D. 19889. Host specificity of S. scabiei var. canis (Acari: Sarcoptidae) and the role of host odor. J Med Ent 25:52-56.

Hawkins JA, McDonald RK, Woody BJ. 1987. Sarcoptesscabiei infestation in a cat. JAVMA 190:1572-1573.

Linquist WD, Cash WC. 1973. Sarcoptic mange in a cat. JAVMA162:639-640.

Bussieras J. 1984. Un cas exceptionnel de gale sarcoptique chez le chat. Prat Med Chir Anim Comp 19:375-377.

Figure 5-33.Sarcoptesscabei. Dorsal view of an adult female showing the large triangular spines that appear on the body.

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