The therapeutic efficacy and prophylactic activity of doramectin against Dictyocaulus viviparus in cattle.
Three groups of 8, 4-month-old male Jersey or Jersey-cross calves were infected with 2400 Dictyocaulus viviparus L3 larvae and either left untreated or injected subcutaneously with 200 micrograms/kg doramectin 5 or 25 days after infection (DAI). Lungworms were found in all untreated cattle (geometric mean = 49) at necropsy 39 or 40 DAI. None was found in any of the treated cattle. In a second experiment, groups of 6, 8-month-old calves were untreated or injected with 200 micrograms/kg doramectin 28, 21 or 14 days before each calf was challenged with 2700 D viviparus larvae. Lungworms were recovered at necropsy 32 to 34 DAI. The geometric mean worm burden in the untreated cattle was 550. This was reduced by 100%, 99.5% and 94.1% in calves treated with doramectin 14, 21 or 28 days, respectively, before infection. It was concluded that doramectin is a highly effective anthelmintic against D viviparus adult or L4 infections of cattle, and that reinfection of treated cattle will be significantly reduced for at least 28 days after treatment.
Barton
N J
NJ
Department of Agriculture, Regional Veterinary Laboratory, Bairnsdale, Victoria.
Mitchell
P J
PJ
Hooke
F G
FG
Reynolds
J
J
D000818:Animals; D000871:Anthelmintics / Q000592:standards / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000517:prevention & control; D004021:Dictyocaulus / Q000187:drug effects / Q000254:growth & development; D004022:Dictyocaulus Infections / Q000188:drug therapy* / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000469:parasitology; D005260:Female; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000592:standards / Q000627:therapeutic use; D007814:Larva / Q000187:drug effects; D008297:Male; D011897:Random Allocation
D000871:Anthelmintics; D007559:Ivermectin; C084101:doramectin