Persistent efficacy of doramectin pour-on against artificially induced infections of nematodes in cattle

• Published in: Veterinary parasitology Vol. 82; no. 4; pp. 297 - 303
• Main Authors: Molento, M.B., Trudeau, C., Prichard, R.K., Zimmerman, G.L., Johnson, E.G., Marley, S., Conder, G.A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.1999
• Subjects: Abomasum - parasitology; Administration, Topical; Animals; Anthelmintics - administration & dosage; Anthelmintics - standards; Anthelmintics - therapeutic use; Cattle; Cattle Diseases - drug therapy; Cattle Diseases - parasitology; Cattle-nematode; Dictyocaulus - drug effects; Doramectin; Endectocide; Female; Haemonchus - drug effects; Intestine, Large - parasitology; Intestine, Small - parasitology; Ivermectin - administration & dosage; Ivermectin - analogs & derivatives; Ivermectin - standards; Ivermectin - therapeutic use; Lung - parasitology; Male; Nematoda - drug effects; Nematode Infections - drug therapy; Nematode Infections - parasitology; Nematode Infections - prevention & control; Nematode Infections - veterinary; Oesophagostomum - drug effects; Ostertagia - drug effects; Persistent efficacy; Pour-on; Random Allocation; Trichostrongyloidea - drug effects; Pour-on; Endectocide; Cattle-nematode; Doramectin; Persistent efficacy
• ISSN: 0304-4017; 1873-2550
• DOI: 10.1016/S0304-4017(99)00030-8

Two studies were conducted to determine the persistent efficacy of doramectin pour-on against an artificial, trickle challenge of mixed nematodes in calves. In each study, 42, 4–8 months old calves were randomly assigned into four groups of 10 animals each (T1–T4), plus two larval-viability monitor animals. All animals were treated with fenbendazole (10 mg kg −1) 14 days prior to the start of the study to clear any existing infection. Doramectin pour-on at 500 μg kg −1 was used on each animal in Groups T2, T3, and T4 with intervals of 1 week (Day 0, 7, and 14, respectively). Calves in Group T1 were treated with saline solution on Day 0 and at the same volumetric rate (1 ml 10 kg −1) as the doramectin treated animals. All treatments were applied in a single passage along the midline of the back, from the withers to the tailhead. Subsequently, trickle inoculations with infective larvae were administered to all calves for 22 consecutive days (Days 14–35). Doramectin pour-on provided ≥91.9% efficacy against challenge with Dictyocaulus viviparus, Haemonchus spp., and Ostertagia ostertagi for up to 35 days post-treatment and against challenge with Cooperia oncophora, Cooperia punctata, and Oesophagostomum radiatum for up to 28 days post-treatment.