Persistent activity of doramectin and ivermectin against Ascaris suum in experimentally infected pigs

• Published in: Veterinary parasitology Vol. 82; no. 3; pp. 235 - 241
• Main Authors: Lichtensteiger, C.A, DiPietro, J.A, Paul, A.J, Neumann, E.J, Thompson, L
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 12.04.1999
• Subjects: Animals; ANTHELMINTHIQUE; Anthelmintic; ANTHELMINTICS; Anthelmintics - pharmacology; Anthelmintics - therapeutic use; ANTIHELMINTICOS; Ascariasis - drug therapy; Ascariasis - prevention & control; Ascariasis - veterinary; Ascarids; ASCARIS SUUM; Ascaris suum - drug effects; Avermectin; CERDO; CONTROL DE NEMATODOS; Doramectin; EXPERIMENTAL INFECTION; INFECCION EXPERIMENTAL; INFECTION EXPERIMENTALE; Intestine, Small - parasitology; IVERMECTIN; Ivermectin - analogs & derivatives; Ivermectin - pharmacology; Ivermectin - therapeutic use; IVERMECTINA; IVERMECTINE; Linear Models; LUTTE ANTINEMATODE; NEMATODE CONTROL; PORCIN; Random Allocation; Stomach - parasitology; SWINE; Swine Diseases - drug therapy; Swine Diseases - prevention & control; Anthelmintic; Ascarids; Swine; Doramectin; Ascaris suum; Avermectin; Ivermectin
• ISSN: 0304-4017; 1873-2550
• DOI: 10.1016/S0304-4017(99)00018-7

A study was conducted to investigate the persistent nematocidal activity of two avermectins against experimentally-induced infections of Ascaris suum in swine. Seventy-two nematode-free cross-bred pigs of similar bodyweight were randomly allotted to nine treatment groups of eight pigs each. Eight of the groups were treated with injectable solutions containing 300 μg of doramectin/kg (IM) or 300 μg of ivermectin/kg (SC) either 0 (same day), 7, 14, or 21 days prior to an oral challenge of 50 000 embryonated A. suum eggs. The ninth group (control) was challenged in parallel without any avermectin treatment. At 41 or 42 days after challenge, pigs were euthanatized and adult and larval stages of A. suum were collected from the gastrointestinal tract of each pig and counted. Both avermectins significantly ( P < 0.0002) reduced nematode counts when given on the day of challenge (0 days prior), and the efficacy was 100% and 97.5% for doramectin and ivermectin, respectively. Doramectin given 7 days prior to challenge significantly ( P < 0.0001) reduced nematode counts, and the efficacy was 98.4%. For all other avermectin-treatment groups, nematode counts were not significantly reduced compared to those in control pigs. These data indicated that anthelmintic activity of ivermectin against A. suum persisted for less than 7 days and the activity of doramectin persisted for more than 7, but less than 14 days.