Impact of shampooing or water immersion on the effectiveness of Effipro^® Duo against the further development of flea eggs: a randomised, blinded, controlled study in dogs

Introduction

This study was intended to identify any possible impact that water immersion and/or shampooing may have had on the effectiveness of a fipronil-pyriproxyfen spot-on formulation (Effipro^® Duo, Virbac, Carros, France) against the further development of flea eggs collected from dogs experimentally infested with fleas (Ctenocephalides felis).

Materials and Method

Animals and groups: 30 healthy dogs (>6 months, 5.46 kg to 18.29 kg) randomly allocated to either
- Group 1: shampooed 2 hours prior to placebo administration and 30 and 58 days post administration,
- Group 2: shampooed 2 hours prior to product administration,
- Group 3: shampooed 30 and 58 days post product administration,
- Group 4: water immersed 30 and 58 days post product administration
- Group 5: product administration only
No treatment with an acaricide/insecticide for 12 weeks or with an insect growth regulator within 6 months. Pre-treatment flea egg hatch had to be >25%.
Treatment: Groups 2 to 5 received one 0.67 ml pipette (Effipro^® duo S) for a dog weighing ≥2.1 kg to 10.0 kg or one 1.34 ml pipette (Effipro^® duo M) for a dog weighing ≥10.1 kg to 20.0 kg on day 0.

Exposure and measurements: Each dog was first infested with 100 fleas 11 days before treatment, for egg collection for inclusion and randomization purposes. Dogs were further
infested with at least 50 gravid fleas (from donor dogs) on days 1, 28, 56, 70 and 84. Flea eggs were collected for two consecutive nights following infestations and incubated for approximately
35 days to allow adult flea emergence.

Analysis: The proportion of emerged adult fleas (relative to the number of eggs collected and incubated) were used to calculate the percentage inhibition of the emergence with the following formula:Efficacy (%) = 100 x (Mc – Mt)/Mc, using arithmetic mean of the proportion of emerged adult fleas in the control group (group 1,
Mc) and the treated group (group 2, 3, 4 or 5, Mt).

The groups were compared at each time point usinf a one-way ANOVA with a treatment effect on the arithmetic mean emerged adult fleas. 
 

Results 

Conclusion

Effipro^® Duo spot-on formulation was effective for 3 months after application to prevent the multiplication of fleas (Ctenocephalides felis) in dogs. Water immersion and shampooing had no significant impact on its efficacy against the further development of flea eggs.