Effect of treatment with levamisole or fenbendazole on primary experimental Dictyocaulus viviparus infection and on resistance in calves

Abstract

Based on faecal larval counts, respiratory rates and live-weight gains, the anthelmintics levamisole and fenbendazole were equally efficacious against primary infection with Dictyocaulus viviparus in calves. Calves that were treated with levamisole or fenbendazole resisted the live-weight depressing impact of reinfection. Treatment somewhat impaired resistance to establishment of the secondary challenge as determined at necropsy. However, compared with previously uninfected controls, the treated animals harboured significantly fewer D viviparus, showing that they still strongly resisted reinfecting worms becoming established. The animal responses measured did not demonstrate any difference between levamisole and fenbendazole in relation to efficacy or to effect on resistance.

The Response of Lactating Cows and Growing Heifers to Treatment for Parasites

“…The active ingredient in Tramisol (levamisole phosphate), because of its broad spectrum characteristics (Coles et al 1919), was expected to be the anthelmintic most likely to be effective with low-level infestations. The proven efficacy of Tramisol against Dictyocaulus viviparus in calves (Downey 1980) (1977) and was certainly found to be below the average level of parasitic infestation identified by the survey of Barker (1979, pers. commun For personal use only.…”

Lungworm in cattle: treatment and control

“…Although both benzimidazoles and levamisole seem to be equally effective in treating clinical cases (Downey, 1980), there are reports, based on studies conducted in the 70s and 80s (Table 2), of different mortality rates in calves following treatment (Jarrett et al, 1980;McEwan et al, 1979). Some of the histopathology described in these cases is identical to what has been observed in fatal cases of PB in animals that had not been treated (Jarrett et al, 1954(Jarrett et al, , 1957b.…”