Histology of the skin and determination of blood and serum parameters during the recovery phase of sarcoptic manage in cattle after avermectin (Ivomec) treatment.

Calves experimentally infested with Sarcoptes bovis were treated 14 weeks post infectionem with an avermectin pour-on preparation (Ivomec). On day 0 before and 14, 28 and 56 days after treatment mite count, scabies lesion score, histological sections of the skin, blood- (number of erythrocytes, PCV, Haemoglobin, MCV, MCH, MCHC, number of leukocytes, differential blood picture) and serum parameter (GOT/AST, GGT, GLDH, glucose, calcium, magnesium, phosphate, sodium, potassium and chloride) and Sarcoptes specific immunoglobulin G and immunoglobulin M were determined. 14 days after treatment no mites could be found in skin scrapings and the mange lesions were in recovery stage. 28 days after treatment the skin mostly was macroscopically unchanged. On all examination days in skin biopsies hyperkeratosis, mostly accompanied by epidermal hyperplasia and perivascular infiltration with eosinophil granulocytes and mononuclear cells was observed. The dominance of eosinophil granulocytes in the tissue decreased after treatment, while mononuclear cells increased and dominated in most cases on day 28 over eosinophil granulocytes. The differential blood count in most cases showed elevated lymphocytes on all examination days, increase of neutrophil granulocytes and decrease of eosinophil granulocytes between day 0 and 14. Monocytes on day 28 showed a marked decrease, thereafter on day 56 a marked elevation. Slightly increased serum enzyme activities were seen with GLDH and GOT on day 0 before treatment and with GLDH on day 56 after treatment. The specific antibody titer against Sarcoptes antigen showed decreasing immunoglobulin G titre and increasing immunoglobulin M titre during the investigation.