Efficacy of Praziquantel in the Treatment of Platynosomum fastosum in Cats with Natural Infections

Treatments for Platynosomum fastosum-the liver fluke of cats-have been developed based on fecal egg counts. Post mortem fluke counts are required to understand true efficacy. In this study, two praziquantel treatment regimens were evaluated using post mortem fluke counts: a high-dose treatment (HT) of 20 mg/kg body weight (BW) administered intramuscularly (IM) once a day for three consecutive days and a low-dose treatment (LT) of 5 mg/kg BW administered once (IM) and repeated 14 days later. A continual enrolment study design was used with 16 naturally infected cats randomly allocated in blocks of four to the HT (eight cats) or LT (eight cats) group. Treatment success, defined as absence of live flukes post mortem, was determined 10 days after the last treatment. Pre- and post-treatment fecal egg counts (centrifugation with Sheather's sugar flotation solution) and bile egg counts (obtained via percutaneous ultrasound guided cholecystocentesis) were evaluated as supportive efficacy data. Twelve cats completed the study with two cats withdrawn from each group. Neither treatment was 100% effective. In the HT group, three of six cats had live flukes, albeit low numbers, at post mortem, while all six LT group cats had live flukes. While fecal and bile egg counts were reduced in both group, they were not reflective of the true infection status of the cats post mortem.