Prophylactic Effects of Levamisole Hydrochloride by Intermittent Medication against Dirofilaria immitis Infection in Dogs

Abstract

Prophylactic effects of levamisole hydrochloride (LH) on Dirofilaria immitis infection and itsside reaction in hematological and blood chemical findings were assessed in 9 infected dogs. Thesedogs were exposed to natural D. immitis infection throughout the infectious season in Japan (from Julyto Setpember). Additionally, they were infected with a single experimental inoculation of infectivelarvae on July 31 (8 dogs) or on August 2 (1 dog as control). The medicated group was given twocourses of LH at a dosage of 5mg/kg, t.i.d.(15mg/kg/day) for 5days, on 18th to 22nd August andon 20th to 24th October. Five medicated dogs were sacrificed on the 170th day (4 dogs) or the212th day (1 dog) of experimental infection and the other four on the 210th day (2 dogs) or the 218thday (2 dogs).
Necropsy revealed that all the medicated dogs were free from worms in their heart and bloodvessels and that 4 controls harbored D. immitis, the mean infectious being 42.6%. Hematologicaland blood chemical findings showed no substantial side effects of LH, except a moderate increaseof serum GPT. No abnormality was recognized in general clinical findings in any dog during thecourse of experiment.