Abstract :
Sheep are parasitised by a diverse range of internal and external parasites. The majority of
adult helminths and many of the ectoparasites affecting sheep, are grossly visible to the
naked eye due to their size. With internal parasites, however, observation and detection
of adult stages is generally only possible on post-mortem examination of the appropriate
organs and viscera. More often, the presence of parasites in the gastrointestinal tract,
lungs and liver can be detected by parasitological examinations of appropriate samples,
usually faeces, for the presence of their eggs, cysts or larval stages. This review focuses on
the clinical and laboratory diagnostic approaches to a number of important parasitic diseases
of sheep, in particular, parasitic gastroenteritis and the detection of species showing
the presence of anthelmintic resistance, as well as other diseases, such as liver fluke and
coccidiosis. The diagnosis of ectoparasite infections is generally much more straightforward,
because of their size and location on the skin. However, misidentification can occur
without appropriate experience in parasite identification. Accurate and correct diagnosis is
fundamental to good parasite control, otherwise inappropriate or consequential, apparent
treatment failures may occur.
