CIVETAN   23983
CENTRO DE INVESTIGACION VETERINARIA DE TANDIL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Eprinomectin concentrations in plasma and in Rhipicephalus (Boophilus) microplus: relationship with its efficacy in cattle.
Autor/es:
A. LIFSCHITZ, S. NAVA, A. MANGOLD, F. IMPERIALE, M. BALLENT, J. CANEVARI, C. LANUSSE
Lugar:
Gramado
Reunión:
Congreso; XVIII Congreso Brasilero de Parasitología Veterinaria,; 2014
Resumen:
Eprinomectin (EPM) is a macrocyclic lactone used against endo-ectoparasites without withdrawal time in milk and meat after its pour-on administration at 0.5 mg/kg. Previous experiments evaluated the efficacy of EPM against Rhipicephalus (Boophilus) microplus in cattle. The aim of the current work was to study the relationship between the systemic availability and the tick concentrations of EPM as well as the efficacy of EPM against R. (B.) microplus after its administration at two different dose rates. A standardized pharmaco-parasitology study was performed. Eighteen Braford cattle naturally infected with R. (B.) microplus were divided in three experimental groups with a similar level of infestation (Kruskal-Wallis test, P > 0.05): control group and treated groups with EPM pour-on (1 and 1.5 mg/kg). Samples of blood and tick with different stage life were taken between 0 and 21 days post-administration to measure EPM concentrations by HPLC. Female ticks (4,5-8 mm) on the cattle were counted between 1 and 21 days post-treatment to evaluate the efficacy of EPM. Plasma concentrations of EPM have shown a linear relationship related to the level of dose rate administered. The peak plasma concentrations were in a range between 13.8 and 90 ng/ml that guarantee the milk drug concentrations below the maximum residues level. High concentrations of EPM were detected in ticks. EPM concentrations in R. (B.) microplus reflect the plasma concentrations from the hour 30 post-treatment (r 0.84; P 0.0002). The EPM efficacy calculated with the Henderson-Tilton formula were 71 % and 81 % (3 days post-administration) and 92.9 % and 98.9 % (21 days post-administration) after EPM treatment at 1 and 1.5 mg/kg, respectively. Therefore EPM may be a valid tool to tick control in cattle, particularly in dairy production systems.