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→Clinical Signs
===Clinical Signs===
===Clinical Signs===
In sheep, fasciolosis may present as acute or chronic manifestations. Acute fasciolosis usually occurs between September and December and is caused by large numbers of immature ''[[Fasciola hepatica]]'' migrating through the liver parenchyma and causing massive damage. If sheep are not exposed to at-risk pasture until later in the year, acute fasciolosis may occur as late as the following Feburary. Hepatic damage caused by migration of fluke larvae gives clinical signs including lethargy, pallor, dyspnoea and death in both young and adult animals. Handling of sheep may cause liver rupture and sudden death, and sudden death may also occur due to Black's disease (''Clostridium novyi'' type B) or bacillary haemoglobinuria (''Clostridium novyi'' type D) in unvaccinated sheep. This is a result of larval migrationg facilitiating the activation of clostridial spores. A more subtle, sub-acute presentation is also possible, which is characterised by significant weight loss over one to two weeks, a normochromic anaemia and an enlarged, haemorrhagic liver.
In sheep, fasciolosis may present as acute, chronic, or infrequently sub-acute manifestations. Acute fasciolosis usually occurs between September and December and is caused by large numbers of immature ''[[Fasciola hepatica]]'' migrating through the liver parenchyma and causing massive damage. If sheep are not exposed to at-risk pasture until later in the year, acute fasciolosis may occur as late as the following Feburary. Hepatic damage caused by migration of fluke larvae gives clinical signs including lethargy, pallor, dyspnoea and death in both young and adult animals. Handling of sheep may cause liver rupture and sudden death, and sudden death may also occur due to Black's disease (''Clostridium novyi'' type B) or bacillary haemoglobinuria (''Clostridium novyi'' type D) in unvaccinated sheep. This is a result of larval migrationg facilitiating the activation of clostridial spores.
Chronic fasciolosis in sheep is caused by adult flukes in the bile ducts and is usually seen in February and March. However, cases may present in early summer if snails become infected during the winter. Progressive weight loss over weeks to months results in poor body condition, and anorexia is often seen. Other features include anaemia, and ascites and/or submandibular oedema due to hypoalbuminaemia.
In some cases, sub-acute fasciolosis may occur if infections has occured over a prolonged period. In these instances, disease is caused by both adult flukes and larvae and ill thrift, lethargy, dyspnoea is seen from around December to March.
'''Sub-clinical effects'''
'''Sub-clinical effects'''