Evaluation of the Prevalence and Risk Factors for Dictyocaulus viviparus Infection in First-lactation Cows:

Lungworm disease has classically been described in young calves and occasionally yearlings, with rare occurrences of a re-infestation syndrome in adults. The condition, like other nematode-induced disorders, has decreased in incidence among dairy herds with the widespread use of endectocides in replacement stock. However, in the last decade in Eastern Canada, anecdotal reports from practitioners and articles in farming journals give the impression that the incidence of lungworm disease in adult lactating cattle is higher than usual. At the same time, pasture management methods are changing in some of the dairies where grazing of replacement stock and/or lactating cows is still practiced. Bovine practitioners lack information on actual prevalence of the parasite and risk factors that predispose a herd to infection. A randomized cross-sectional survey was conducted to establish the prevalence of herds with Dictyocaulus viviparus (D.v.) infected first-lactation cows in the province of Quebec and to evaluate risk factors associated with herd infection.