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A field trial on the efficacy of abamectin (avermectin B1a) against Ascaris suum, Trichuris suis, and Sarcoptes scabiei was performed. Ninety pigs that showed clinical manifestation of S. scabiei infestation were selected from a farm of 20,000 pigs. Clinical signs of sarcoptic mite infestation included pruritus, erythema, and papules which were observed in 89 (99%), 84(93%) and 83(92%) pigs, respectively. Upon skin scraping, the presence of S. scabieiadult warms was confirmed in 14 pigs (15.6%). Among the 90 pigs, 40 pigs were also infected with either A. suum and/or T. suis. Pigs were divided into two groups for treatment, in which abamectin (avermectin B1a, 1% w/v) was administered via the intramuscular route in a group of 45 pigs, while the rest 45 pigs received abamectin via the subcutaneous route. After treatment, sarcoptic mites were found from 4 pigs (4.5%) at 3rd week post treatment; 3(6.7%) pigs in the intramuscular injection group and 1 (2.3%) pig in the subcutaneous group. However, no pigs showed sarcoptic mites in the skin scrappings at 8 weeks post treatment. Most clinical signs of sarcoptic mite infestation disappeared by 3rd week after treatment in both groups. Eggs of A. suum and T. suis were observed in the feces of 11 pigs (12.2%) at the first week, but none at the 2nd and 3rd weeks post treatment. However, eggs of T. suis reappeared in the feces of two pigs at 6, and 8 weeks post treatment. Routes of injection did not affect the efficacy of abamectin.
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