An evaluation of the efficacy, clinical safety, blood levels and milk concentrations of flumethrin and cypermethrin formulations used for tick control in cattle

Abstract

Introduction - Ticks and tick-borne diseases are a global problem. Cypermethrin and flumethrin are synthetic pyrethroid acaricides widely used for tick control in cattle. As is the case for all families of acaricides, pyrethroid resistance in ticks is one of the most important problems in cattle husbandry by causing major health problems and economic losses. Therefore, continuing studies of the susceptibility to resistance of currently used acaricides is essential for effective tick control programs. In addition, measuring blood and milk concentrations of applied acaricides is essential for the evaluation of their efficacy against ticks and potential toxicity to animals and humans. Aim - In this study, the effectiveness of flumethrin and cypermethrin formulations against ticks infesting cattle was determined. Furthermore, the relationship between their blood and milk levels and their clinical effects on cattle were investigated. Materials and methods - Forty eight cattle naturally infested by ticks were divided into two experimental groups and flumethrin (group I, n=37, 1 mg/kg) and cypermethrin (group II, n=11, 5 mg/kg) were dermally applied. Clinical examinations were performed and live ticks on the animals were counted on days 0, 2, 7, 14, 21 and 28. Blood and milk samples were collected on day 2 and 28 and acaricide levels were determined with High Performance Liquid Chromatography; milk was only collected from Group I because the use of cypermethrin is not recommended in lactating cattle. Results - A number of tick species were collected. However, mainly two species, Rhipicephalus turanicus and Rhipicephalus (Boophilus) annulatus, which are common in Turkey, were identified. The decrease in the number of live ticks over time was significant in both experimental groups (p<0.01) and no new tick infestations were observed. There was no significant difference in the efficacy of the two acaricides (p>0.05). No adverse clinical effects were observed during the 28 days. The mean blood concentrations of flumethrin and cypermethrin were 0.29 +/- 0.057 and 1.55 +/- 0.28 mu g/mL, respectively, on day 2, and increased to 0.47 +/- 0.22 and 4.77 +/- 1.86 mu g/mL, respectively, on day 28. Flumethrin was not detected in milk samples and, as per the manufacturer's recommendation, cypermethrin was not applied to lactating animals. Conclusions - Flumethrin and cypermethrin were very effective against ticks for 28 days. Their concentrations in the blood were higher on day 28, which probably explains their effectiveness for 4 weeks. The absence of flumethrin in milk samples was a positive finding for the safety of calves and for public health. No adverse clinical effects were observed in the subject cattle during the study. However, further studies should be performed, using negative control groups and different doses, for a more detailed evaluation.