Lungworms of the Domestic Pig and Sheep

Abstract

Publisher Summary This chapter discusses lungworms infection in domestic pig and sheep. Four species of lungworms infect the domestic pig, all belonging to the genus Metastrongylus. Two species are widely known namely Metastrongylus elongatus and Metastrongylus pudendotectu. They are cosmopolitan in their distribution. Numerous surveys have been made to assess the incidence of lungworms usually in pigs sent for slaughter at bacon factories or abattoirs. The precision with which these surveys have been carried out range from a simple assessment of infection made by incising the lung and examining for the presence of lungworms without any attempt to identify or count the worms to thorough examinations in which the lungworm species have been identified and counted. The life-cycles of M. elongatus and M. pudendotectus are discussed. Light to moderate infections cause no marked clinical symptoms but heavy infections can cause pneumonia and other respiratory diseases and may cause death. At least 14 different species of lungworms are known to parasitize sheep, but only four species are widely distributed and have been the subject of extensive investigations. This review is concerned principally with these four species, namely— Dictyocaulus flaria, Muellerius capillaries, Protostrongylus rufescens, and Cystocaulus ocreatus. There are numerous records of the incidence of lungworm species from different countries. As with the pig lungworms the precision with which these records have been obtained varies from the examination of lungs, usually from healthy sheep sent to abattoirs for slaughter and the identification of any lungworms recovered to records based either on the presence of lesions in the lungs resulting from lungworm infection or on the identification of lungworm larvae in the faeces and Cystocaulus ocreatus. Various methods for the control of lungworm infection in sheep are discussed.