Abstract
Mite infestations in laying hens can cause losses to producers due to stress, reduced egg production and even death of birds. A new species of mite, Allopsoroptoides galli (A. galli), Analgoidea: Psoroptoididae, was recently identified in commercial laying farms in Brazil, causing damage due to its highly aggressive infestation that results in a sharp drop in egg production and culling. The present study evaluated the acaricidal action of a formulation containing fluralaner (Exzolt) against A. galli. Thirty-four laying hens naturally infested with A. galli were equally divided into a fluralaner-treated group and an untreated control group. The fluralaner-treated group received Exzolt in drinking water at a dose of 0.05 mL/kg body weight (equivalent to 0.5 mg fluralaner/kg body weight), twice, 7 d apart. Both groups were followed for 70 d evaluating the level of infestation by counting mites in skin scrapings and assessment of skin lesions. The average mite count of the treated group decreased significantly, dropping from 61.6 to 3.8 mites (D+7 to D+70). The efficacy progressively increased on subsequent days, reaching 98.8% on d +56 post-treatment and 96.9% on d +70. Recovery of skin lesions was observed after administration of Exzolt, showing a marked remission in the degree of lesions (2.5 on d -14 to 0.2 on d +70). The mean number of mites in the untreated control group ranged from 79.3 to 124.1 and the lesion score from 2.6 to 2.9, thus remaining stable throughout the study. The results obtained in the present study demonstrated that Exzolt administered at a dose of 0.05 mL of product/kg body weight (equivalent to 0.5 mg of fluralaner/kg body weight), twice at a 7-d interval, in drinking water was effective in the treatment of the mite Allopsoroptoides galli in naturally infested laying hens.