Moxidectin pour-on for control of natural populations of the cattle tick Boophilus microplus (Acarina: Ixodidae).

Fifty Bos taurus x Bos indicus heifers naturally infested with Boophilus microplus ticks were divided into two groups of 25 heifers each. Individuals of one group were treated with moxidectin 0.5% pour-on at a dosage of 500 microg of moxidectin/kg body weight and heifers from the other group remained as untreated controls. An efficacy higher than 95% was found on days 7-21 after treatment by using female ticks 4.5-8.0 mm long as the main infestation parameter. A lower, but significant efficacy (p < 0.05) was also found on days 1 (32.3% efficacy) and 27 (73.4% efficacy) post-treatment. Significantly (p < 0.05) lower numbers of immature ticks were also observed on heifers of the treated group from days 7 through 27 after treatment. A lower engorgement weight of female ticks from treated heifers was found on days 1 and 21 after treatment. Treatment also affected reproductive performance (oviposition, egg hatch and number of eggs laid) of female ticks collected on Day 1.

Ovicidal action of oxfendazole on sheep nematodes.

Groups of five sheep naturally infested with gastrointestinal nematodes were dosed with oxfendazole at the rates of 2.5, 3.5, or 4.5 mg per kg and a similar group of five kept as controls. Frequent observations were made on worm egg output and the hatchability of the eggs passed. The first ovicidal activity was apparent five hours after treatment. Within eight hours 99.7 per cent or more of the eggs voided were sterile and by 30 hours there was a 99.9 per cent reduction in the numbers of larvae hatching compared with the controls. Within three days of dosing the faeces of the treated sheep were negative for worm eggs.