The efficacy of ivermectin against the eyeworm, Thelazia skrjabini, in experimentally infected cattle.
The anthelmintic efficacy of ivermectin (administered subcutaneously at 200 micrograms kg-1 body weight) was assessed for control of Thelazia skrjabini in experimentally infected calves. Twenty-four uninfected male Holstein calves, 1-2 weeks old, were artificially infected with Thelazia skrjabini by placing 15 third-stage larvae under the third eyelid of calves. The challenge larvae were recovered from naturally infected face flies, Musca autumnalis. The exposed calves were randomly assigned to either an ivermectin treatment group or a control group within pairs ranked by weight. Equal numbers of calves were housed in each of four indoor fly-free rooms. The calves were treated with ivermectin or saline 35 days post-infection, then slaughtered 14 days later to determine eyeworm numbers. All eyes and associated tissues (including the lacrimal glands and ducts) were removed and examined for total number, species and viability of eyeworms. Thelazia skrjabini was found in the control group of calves only. The efficacy of ivermectin against Thelazia skrjabini was thus shown to be 100%.
Kennedy
M J
MJ
Veterinary Pathology Branch, Alberta Department of Agriculture, Edmonton, Canada.
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D007303:Insect Vectors / Q000469:parasitology; D007559:Ivermectin / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D009117:Muscidae / Q000469:parasitology; D011897:Random Allocation; D017205:Spirurida Infections / Q000188:drug therapy / Q000662:veterinary*; D017177:Spirurina / Q000187:drug effects*
D007559:Ivermectin