Efficacy of ivermectin against the swine kidney worm, Stephanurus dentatus.

Ivermectin in solution was given subcutaneously (in the neck) at the rate of 0.5 mg/kg of body weight to 5 sows naturally infected with kidney worm (Stephanurus dentatus). Six similar sows were used as nontreated controls. A total of 114 kidney worms were recovered from daily urine samples of 4 of the 5 treated sows (the 5th sow's samples were negative) during the first 4 days after treatment. Ten kidney worms were recovered from daily urine samples of 1 control sow on the 2nd and 3rd days of the post-treatment period. Examination of urine samples from treated sows for kidney worm eggs showed a precipitous numerical decrease. Treated animals became negative between the 5th and 12th days after treatment, and remained negative until necropsy on the 61st day. Compared with control sows, hatchability of eggs and survival of larvae from treated sows was reduced by 9% and 7%, respectively. Kidney worms were not recovered at necropsy from the treated sows, and a total of 392 kidney worms were recovered from the control sows (av 65).