6,502
edits
Changes
Jump to navigation
Jump to search
→Description
==Description==
==Description==
[[Image:clostridium perfringens.jpg|thumb|right|200px|Clostridium Perfingens. Source: Wikimedia Commons; Author:Don Stalons (1974)]]
[[Image:clostridium perfringens.jpg|thumb|right|200px|Clostridium Perfingens. Source: Wikimedia Commons; Author:Don Stalons (1974)]]
Pulpy kidney is a common, peracute and usually fatal enterotoxaemia of sheep of all ages, caused by the ε toxin of ''Clostridium perfringens'' type D. ''C. perfringens'' is a large, gram positive, anaerobic bacillus that is ubiquitous in the environment and commensalises the gastrointestinal tract of most mammals<sup>1</sup>. Five genotypes of ''Clostridium perfringens'' exist, named A-E, and all genotypes produce potent exotoxins. There are 12 exotoxins in total, some of which are lethal and others which are of minor significance<sup>2</sup>. These are produced as pro-toxins, and are converted to their toxic froms by digestive enzymes. The enterotoxaemias are a group of diseases caused by proliferation of ''C. perfringens'' in the lumen of the gastrointestinal tract and excessive production of exotoxin.
In healthy animals, there is a balance between multiplication of ''Clostridium perfringens'' and its passage in the faeces. This ensures that infection is maintained at a low level. However, ''C. perfringens'' is saccharolytic and is therefore able to multiply rapidly when large quantities of fermentable carbohydrate are introduced to the anaerobic conditions of the abomasum and small intestine, leading to build-up of exotoxin. Gut statis, for example due to insufficient dietray fibre or a high gastrointestinal parasite burden, can also contribute to the accumulation of toxins.
In healthy animals, there is a balance between multiplication of ''Clostridium perfringens'' and its passage in the faeces. This ensures that infection is maintained at a low level. However, ''C. perfringens'' is saccharolytic and is therefore able to multiply rapidly when large quantities of fermentable carbohydrate are introduced to the anaerobic conditions of the abomasum and small intestine, leading to build-up of exotoxin. Gut statis, for example due to insufficient dietray fibre or a high gastrointestinal parasite burden, can also contribute to the accumulation of toxins.
In extreme cases, losses of 10-15% have been reported.
Enterotoxaemia due to ''Clostridium perfringens'' type B causes severe enteritis and dysentery with a high mortality in young lambs (lamb dysentery), but also affects calves, pigs, and foals. The β toxin it produces is highly necrotising and is responsible for severe intestinal damage. ε toxin also plays a part in pathogenesis. The incidence of lamb dysentery declined over the past 20 years or so, due to the widespread use of clostridial vaccines<sup>3</sup>, but the condition is now becoming a problem again as complacency reduces the use of vaccination. Outbreaks of lamb dysentery typically occur during cold, wet lambing periods when lambing ewes are confined to small areas of shelter which rapidly become unhygienic. Most cases are seen in stronger, single lambs<sup>3</sup> because these animals consume the largest quantities of milk, which functions as a growth medium for ''C. perfringens''.
Enterotoxaemia due to ''Clostridium perfringens'' type D causes sudden death in well-grown lambs of between 4 and 10 weeks of age, and in fattening lambs of 6 months to one year old. The condition is associated with a change in diet, which causes rapid multiplication of the bacterium and excessive production of its ε toxin. The incidence of pulpy kidney declined over the past 20 years or so, due to the widespread use of clostridial vaccines<sup>3</sup>, but the condition is now becoming a problem again as complacency reduces the use of vaccination. Outbreaks of lamb dysentery typically occur during cold, wet lambing periods when lambing ewes are confined to small areas of shelter which rapidly become unhygienic. Most cases are seen in stronger, single lambs<sup>3</sup> because these animals consume the largest quantities of milk, which functions as a growth medium for ''C. perfringens''.
Pulpy kidney disease, which is caused by C perfringens
Pulpy kidney disease, which is caused by C perfringens