Treatment of sarcoptic and chorioptic mange in an alpaca (Vicugna pacos) herd with a combination of topical amitraz and subcutaneous ivermectin

Clinical history: An outbreak of intense pruritus and weight loss in a herd of 40 alpacas (Vicugna pacos) in the south-west of France was investigated after the death of 14 adults. One alpaca was referred to a veterinary teaching hospital for diagnosis and treatment but died soon after and one of the dead alpacas was submitted for necropsy. Clinical findings: The remaining alpacas were intensely pruritic with variably severe and extensive alopecia, erythema, lichenification and crusting on the face, ventral abdomen and distal limbs. Superficial skin scrapes from five animals revealed large numbers of Sarcoptes scabiei mites, and less frequent and numerous Chorioptes bovis mites. Coproscopic examinations revealed a median of 1,350 (min 500, max 8800) strongyle epg. The alpaca admitted for treatment was anaemic and hypoalbuminaemic. Skin scrapes revealed copious S. scabiei and C. bovis mites. The two alpacas examined post-mortem had similar skin lesions to those examined on-farm and were cachexic. One had lung lesions attributed to protostrongylid infestation and its liver contained numerous Dicrocoelium spp. adults. Diagnosis: Sarcoptic and chorioptic mange with secondary superficial bacterial skin infection, associated with severe internal parasitism and underfeeding. Treatment and outcome: All 25 alpacas were treated topically with a 3% chlorhexidine shampoo followed by a 0.025% amitraz wash at the initial visit and then 1, 2, 3, 7 and 9 weeks later. A systemic treatment with S/C 500 µg/kg ivermectin was administered at the initial visit and then 2, 7 and 9 weeks later. The alpacas were treated orally with 50 mg/kg praziquantel to control dicrocoeliosis. Nutritional measures, including increased pasture area and supplemental feeding were simultaneously implemented. Pruritus was reduced 1 week after the start of treatment and had resolved after 2 weeks. After 9 weeks, skin lesions were markedly improved. Six months after the initial visit, skin lesions entirely resolved and superficial skin scrapes, taken from half of the animals, were negative for mites. Clinical relevance: This is the first report of the use of two acaricides combined with a chlorhexidine shampoo to successfully treat simultaneous sarcoptic and chorioptic mange in alpacas.