Dermatophilosis in sheep raised under rotational grazing systems on irrigated pastures in the Brazilian semiarid region

Abstract

ABSTRACT: Seventeen outbreaks of dermatophilosis are reported from three farms affecting Santa Inês and Santa Inês x Dorper sheep that were reared in irrigated areas with rotational grazing at a stocking rate of 50 to 100 sheep per hectare, in the Brazilian semiarid region. Most outbreaks occurred after rains and affected sheep of different ages, with morbidity rates of 0.77% to 31%. Clinical signs were dermatitis with crusts that stood out easily and left areas of alopecia. Dermatophilus congolensis was isolated in cultures in 5% sheep blood agar by means of Haalstra’s method. Histologically, the epidermis showed extensive multifocal areas of ortho and parakeratotic hyperkeratosis with intracorneal microabscesses and presence of D. congolensis. Sheep affected were isolated from the flocks and they recovered after treatment with 70,000IU of procaine penicillin G and 70mg of dihydrostreptomycin sulphate per kg of bodyweight. Dermatophilosis is a frequent endemic disease in rotational grazing systems with irrigated pastures and high stocking rates, which occurs with higher frequency after rains and can be controlled efficiently through isolation of the affected sheep, followed by application of a single dose of penicillin and streptomycin.