Efficacy of 1% Permethrin and 2% Permethrin Combined with 1% Piperonyl Butoxide against Rhipicephalus sanguineus Ticks in Naturally Infested Dogs

The aim of the present study was to compare the ixodicide efficacy of 1% permethrin applied as a shampoo-bath in single treatment and a combined formulation of 2% permethrin + 1% piperonyl butoxide applied as powder in a single treatment against Rhipicephalus sanguineus ticks, in naturally infested dogs. Eighteen adult cross-mixed dogs, harboring to at least 20 ticks/animal, were selected on pre-treatment live tick counts. On day 0, the dogs were then divided in 3 groups of 6 animals each, for treatment: Group 1 (G1) received 1% permethrin applied as shampoo-bath (approximately 10 ml/kg bw), according to label instructions. G2 was treated with 2% permethrin + 1% piperonyl butoxide applied as powder, and rubbed as massage on the body, as recommended by the producer. G3 served as a non-treated control. After the treatment, the dogs were checked out for live ticks counting on days 0, 1, 7, and 14. The ixodicide efficacy was assessed based on the percentage reductions of ticks on the days analyzed post-treatment, with respect to the untreated control. Results showed that permethrin alone removed ticks on 81%, 93.1% and 89.6% for days 1, 7 and 14, respectively. The combined formulation of 2% permethrin + 1% piperonyl butoxide exerted a better efficacy of 98.8, 97.7 and 97.0%, respectively. It is concluded that this combined formulation was highly effective at rapidly repelling and killing Riphicephalus sanguineus ticks on naturally infected dogs, showing a significant effect on days 1, 7 and 14 after tick exposure. The sustained high and quick level of efficacy of this combination may well interfere with the transmission of Riphicephalus sanguineus ticks. It is concluded that the sustained high level of efficacy of the permethrin + piperonyl butoxide combination may well exert an additive effect and could interfere with the transmission of Riphicephalus sanguineus ticks.

Comparison of Two Pour-On Formulations of Ivermectin against Gastrointestinal Worms, Fleas and Lice in Naturally Infected Stray Dogs

The aim of the present study was to evaluate the efficacy of two commercial pour-on ivermectin formulations against intestinal parasites (IP), fleas and lice in naturally infested stray dogs. Eighteen crossbreed dogs with eggs of IP as well as adult fleas and lice were included in the trial. On day 0, the dogs were randomly divided into 3 groups of 6 animals each: a group receiving a single pour-on treatment with 0.5% ivermectin (500 mcg/kg), a group treated similarly with 0.2% iver-mectin (200 mg/kg), and a control group. Fecal and skin analyses were carried out on days 0, 7, 14, 21 and 28 to determine the reduction of eggs and the number of fleas and lice. Weight gain was also measured on day 28. On day 30, the dogs were humanely sacrificed in order to count adult IP. Efficacy was measured as the percentage of the reduction of eggs per gram fecal mass (EPGF), of adult IP, fleas and lice relative to the control group. For the eggs of IP, ivermectin at 0.5% showed an efficacy of 100% against ascarids and 79% against Ancylostoma caninum. ivermectin at 0.2% removed 90.2% of the ascarids and 50.4% of A. caninum. For adult IP, the efficacy of 0.5% iver-mectin against Toxocara canis and A. caninum was 100%, and for 0.2% ivermectin it was 62.4% and 76.4% for T. canis and A. caninum, respectively. Both compounds were 100% effective against lice and 96% and 71.1% efficacious against fleas, respectively. However, neither treatment was effective against Dypilidium caninum. Weight gain in treated dogs was statistically different from that of the controls (p < 0.05). We concluded that 0.5% pour-on ivermectin showed better efficacy than 0.2% pour-on ivermectin in the reduction of eggs and adult intestinal parasites and fleas;it was similarly efficacious against lice.