Liver fluke control in cattle: why, when and how?

The liver fluke is a common helminth parasite of cattle and sheep and can also infect a variety of other domestic animals and wildlife species such as hares and rabbits; it is also zoonotic. The impact of infection and the expression of disease differs somewhat between cattle and sheep and this has implications in terms of control in both species. The consequences of fasciolosis in cattle can be considered under three broad headings: anaemia directly caused by adult parasites feeding on blood; liver damage with manifestations including metabolic and endocrine dysfunction; and immunomodulation that can alter the host responses to other pathogens, notably bovine tuberculosis. The life cycle and epidemiology of Fasciola hepatica are well understood, but practical control options other than anthelmintics, are generally limited by topographical and management constraints. There is a relatively small choice of flukicidal products and several have meat or milk withdrawal times that render them difficult and/or uneconomic to incorporate into routine farm health management practices. This paper reviews and summarises some of the key aspects of the pathology, impact and epidemiology of liver fluke in cattle in order to provide veterinary clinicians with a rational basis for control so that they can tailor their advice appropriately.