Sarcoptic Mange (Scabies)
This very contagious disease is spread by direct contact or indirectly by fomites. The causative mite, Sarcoptes scabiei var bovis, can be transmitted to humans and is a reportable disease. Lesions start on the head, neck, and shoulders and can spread to other parts of the body; pruritus is intense. Papules develop into crusts, and the skin thickens and forms large folds. The whole body may be involved in 6 wk. Diagnosis is made by deep skin scrapings, skin biopsy, or response to therapy. Treatment is as for psoroptic mange (see below).
This reportable disease, caused by Psoroptes ovis, does not spread to humans. It is seen in range and feedlot beef cattle from the central and western states of the USA, with the largest numbers of outbreaks reported from Texas, New Mexico, Oklahoma, Kansas, Colorado, and Nebraska. Intense pruritus usually begins on the shoulders and rump; papules, crusts, excoriation, and lichenification are seen. Lesions may cover almost the entire body; secondary bacterial infections are common in severe cases. Death in untreated calves, weight loss, decreased milk production, and increased susceptibility to other diseases can occur.
Treatment can be done by spray dipping or vat dipping; topical application of nonsystemic acaricides; and oral, topical, or injectable formulations of systemic drugs. Spray dipping is time consuming but useful for small herds, whereas vat dipping is efficient but fairly expensive and difficult to manage (use of large volumes of water, disposal of wash solution). In the USA, 0.5–0.6% toxaphene spray (28-day withdrawal time); 0.3% coumaphos, 2 dippings (no withdrawal time); 0.20–0.25% phosmet, 2 dippings (21-day withdrawal time); or 2% hot lime-sulfur dip, 3 dippings (no withdrawal time) can be used for dipping. Outside the USA, other treatments are available, eg, 0.1% phoxim, 0.075% diazinon, and 0.025–0.050% amitraz. Dippings should be repeated at 10- to 14-day intervals. Only hot lime-sulfur is registered for use on lactating dairy cows. The topical application of flumethrin (2 mg/kg, twice at a 10-day interval) is also available in many countries outside the USA. Injectable formulations of avermectins (ivermectin and doramectin) and milbemycins (moxidectin) are approved for control of psoroptic and sarcoptic mange at 200 μg/kg (not in lactating dairy cattle). Although one treatment is effective, cattle should be isolated for 2 wk after treatment. Eprinomectin is available as a pour-on formulation at 500 μg/kg. It is approved for the control of sarcoptic mange (no withdrawal time). More recently, a long-acting formulation of moxidectin was introduced. The drug is administered at the ear base at a dosage of 1 mg/kg, but is not for use in lactating dairy cattle. This formulation is also approved for the control of sarcoptic mange and helps control chorioptic mange.
Chorioptic Mange (Leg Mange)
This reportable disease, caused by Chorioptes bovis, does not affect humans. It is the most common type of mange in cattle in the USA; it is more prevalent during the winter and often spontaneously regresses in summer. The pastern areas of the legs are preferred sites for the mites. A high proportion of cattle can be infested without showing clinical signs. Lesions start as papules, crusts, and ulcerations on the legs and can spread to the udder, scrotum, tail, and perineal area. Cattle can be treated with 0.25% crotoxyfos spray at high pressure to completely wet the animal; the other dips used for bovine psoroptic scabies are also effective against Chorioptes. They should be done twice at 10- to 14-day intervals. Lime-sulfur dip weekly for 4–6 dips is effective. Ivermectin, doramectin, eprinomectin, and moxidectin applied topically as a pour-on at 500 μg/kg are effective against chorioptic mange. The injectable formulations of these drugs at 200 μg/kg are considered an aid in the control of Chorioptes. With the exception of eprinomectin, these drugs are not approved in lactating dairy cattle.
Demodex bovis is transferred from cow to calf while nursing and may cause considerable damage to hides. Pruritus is absent. Lesions consist of follicular papules and nodules, especially over the withers, neck, back, and flanks. Ulceration, abscesses, and fistulae can develop due to follicular rupture or secondary infection. Diagnosis is made by deep skin scrapings. Bovine demodicosis usually is benign, although the course may extend for many months. Recovery is usually spontaneous; consequently, treatment is rarely done. Trichlorfon dips (2%) every other day for 3 treatments have been reported to be curative.
Psorergatic Mange (Itch Mite)
Psorergates bos has been reported in cattle in the USA, Canada, and South Africa. Affected animals show mild, patchy alopecia and pruritus. The disease does not cause significant economic losses; thus, animals are usually not treated. Several dips and injectable ivermectins and milbemycins are effective in controlling this infestation.
Last full review/revision July 2011 by Bertrand J. Losson, DVM, PhD, DEVPC; Bernard Mignon, DVM, PhD, DEVPC