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[[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 mammals¹. 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 significance². These are produced as pro-toxins, and are converted to their toxic forms by digestive enzymes such as trypsin. 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.

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 mammals¹, although type D is found less abundantly in healthy animals than the other genotypes^ivis. 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 significance². These are produced as pro-toxins, and are converted to their toxic forms by digestive enzymes such as trypsin. 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.  

Enterotoxaemia due to ''Clostridium  perfringens''  type D causes sudden death in sheep of any age, particularly well-grown lambs of between 4 and 10 weeks of age and fattening lambs of 6 months to 1 year old^lewis. Rams are also susceptible when they are subjected to an incraesed plane of nutrition prior to mating. The condition is associated with a change in diet, for example to include lush grass or high proportions of concentrate. This leads to rapid multiplication of the bacterium and excessive production of its ε toxin. ε toxin causes vascular damage, particularly of the capillaries in the brain^merck. The incidence of pulpy kidney declined over the past 25 years or so, due to the widespread use of clostridial vaccines³, but the condition is now becoming a problem again as complacency reduces the use of vaccination. At its most extreme, pulpy kidney can cause losses of 10-15% of the lamb crop. The disease can also occur in cattle, but this is rare^{ref 2?}.

Enterotoxaemia due to ''Clostridium  perfringens''  type D causes sudden death in sheep of any age, particularly well-grown lambs of between 4 and 10 weeks of age and fattening lambs of 6 months to 1 year old^lewis. Rams are also susceptible when they are subjected to an incraesed plane of nutrition prior to mating. The condition is associated with a change in diet, for example to include lush grass or high proportions of concentrate. This leads to rapid multiplication of the bacterium and excessive production of its ε toxin. ε toxin causes vascular damage, particularly of the capillaries in the brain^merck. The incidence of pulpy kidney declined over the past 25 years or so, due to the widespread use of clostridial vaccines³, but the condition is now becoming a problem again as complacency reduces the use of vaccination. At its most extreme, pulpy kidney can cause losses of 10-15% of the lamb crop. The disease can also occur in cattle, but this is rare^ivis.