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Conference abstract, 2008


Areskog, Marlene; Rydzik, Anna; von Samson-Himmelstjerna, Georg; Höglund, Johan


An experiment was carried out to study the possible interaction between immunosuppression and efficacy of anthelmintic treatment in young cattle. Two groups (A and B) each of seven calves were experimentally inoculated at the start of the experiment with an equal mixture of 30,000 infective third stage larvae of Cooperia oncophora and Ostertagia ostertagi. Blood parameters and faecal egg counts (FEC) were then monitored from day 0 until day 35. The calves in B were immunosuppressed by intramuscular injections of short and long term acting dexamethasone (Dexadreson® vet. Intervet 0.08 mg/kg and Vorenvet® vet. Boehringer Ingelheim Vetmedica 0.25 mg/kg) at days 22 And 24, respectively. Three days post patency (day 24) groups A and B were injected subcutaneously with ivermectin (Ivomec inj., Merial) at the normal dose rate (0.2 mg/kg). The faecal egg count revealed a significant difference (p<0.001) in FEC patterns between groups A and B. Although, both groups still excreted eggs (100-200 epg) 11 Days post anthelmintic treatment, there was a significant (p=0.025) difference in the reduction of eggs in groups A and B between days 23 and 35, where group A had a higher reduction. After 35 days, 10 animals from both groups were sacrificed, and established gastrointestinal worms were collected and counted. No O. ostertagi were found in the abomasums, but low numbers of C.oncophora remained in the small intestines. Overall, this experiment showed that the animals were immunosuppressed dexamethasone and also indicated that there might be a possible interaction between the efficacy of anthelmintic treatment and immunity.

Published in


XV Brasilian Congress of Veterinary Parasitology