The efficacy of two anthelmintics against ascarids and hookworms in naturally infected cats

Abstract

A trial was conducted to establish the comparative efficacy of two different products (A: pyrantel embonate plus praziquantel, B: milbemycin oxime plus praziquantel), against natural infestations of ascarids and hookworms in cats. Young cats (about 6 – 36 months of age) were obtained from feral colonies. The infection was confirmed by fecal egg count. The products were used at the recommended dosage rates, where specifically product A’s dose was tailored to the exact weight of each animal by fractionating the tablets. In the case of product B, the recommended dosage rate was strictly applied relative to the size of tablet or half tablet. Feces were collected daily after treatment and all excreted worms - recovered and identified. Seven days after treatment, the cats were euthanased and processed for worm recovery. Efficacy was calculated by the critical method for each individual animal. The majority of feral cats captured were infected with hookworm alone and a relatively low number were found to be infected with ascarids. Most cats infected with ascarids were also infested with hookworms. A relatively low percentage were infested with tapeworms. The percent efficacy was calculated as a mean of eight cats per group, and showed 100% efficacy of both products against Toxocara spp.. Against Ancylostoma spp. pyrantel/praziquantel was 99.1% effective, while the efficacy of milbemycin/praziquantel was 93.5%. Some of the results obtained indicate that if the dosage rate of milbemycin/praziquantel is on the lower margin (mg/kg) of the weigh class the efficacy may be reduced in those individual animals.