Changes

In young lambs, the only change observable on post-mortem examination may be the presence of a few hyperaemic areas on the intestine and a fluid-filled pericardial sac^merck. Intestinal lesions may even be absent^ivis. Animals, particularly older ones, may have myocardial haemorrhages as well as petechiation of visceral surfaces and abdominal muscles^{vet path, merck, ivis}. Pulmonary oedema and congestion is often present and there may be pleural, peritoneal or pericardial effusions^{merk, ivis}.. The fluid is variable in volume and can be straw or red coloured, sometimes containing fibrin clots^ivis. The kidneys often rapidly autolyse, as suggested by the name "pulpy kidney", but this is not a pathognomic finding.  

In young lambs, the only change observable on post-mortem examination may be the presence of a few hyperaemic areas on the intestine and a fluid-filled pericardial sac^merck. Intestinal lesions may even be absent^ivis. Animals, particularly older ones, may have myocardial haemorrhages as well as petechiation of visceral surfaces and abdominal muscles^{vet path, merck, ivis}. Pulmonary oedema and congestion is often present and there may be pleural, peritoneal or pericardial effusions^{merk, ivis}.. The fluid is variable in volume and can be straw or red coloured, sometimes containing fibrin clots^ivis. The kidneys often rapidly autolyse, as suggested by the name "pulpy kidney", but this is not a pathognomic finding.  

Neurologic signs are explained by lesions in the central nervous system, which are most specific and diagnostic for the disease. These consist of bilatterally symmetrical focal malacia of the basal ganglia, substantia nigra and thalamus and bilaterally symmetrical demyelination in the internal capsule, subcortical white matter and cerebellar peduncles. The harmful effect of the toxin on endothelium is particularly obvious in the brain. Damaged endothelial cells develop pyknotic nucelei and the vessels become surrounded by oedema. Ultrastructurally, the perivascular astrocyte end-feet are markedly swollen.

Lesions of the central nervous system account for the neurologic signs sometimes seen. There is a bilaterally symmetrical focal malacia of the basal ganglia and thalamus, with demyelination occuring in the internal capsule, subcortical white matter and cerebellar peduncles^{vet path}. Histological examination of the brain is often used to confirm a diagnosis of pulpy kidney^dos. eriaxonal and intramyelinic oedema in cerebellar white matter and swelling of axon terminals and dendrites in grey matter adjacent to lateral ventricles. Swelling of mitochondria is also an early feature. Occlusion of capillaries by aggregated platelets, accompanied by petechiae in relation to the malacia, suggests that changes in vascular endothelium may be the primary effect of the toxin.The harmful effect of the toxin on endothelium is particularly obvious in the brain. Damaged endothelial cells develop pyknotic nucelei and the vessels become surrounded by oedema. Ultrastructurally, the perivascular astrocyte end-feet are markedly swollen.

 

The ultrastructural changes on experimental disease consist of periaxonal and intramyelinic oedema in cerebellar white matter and swelling of axon terminals and dendrites in grey matter adjacent to lateral ventricles. Swelling of mitochondria is also an early feature. Occlusion of capillaries by aggregated platelets, accompanied by petechiae in relation to the malacia, suggests that changes in vascular endothelium may be the primary effect of the toxin. This concept is supported by eveidence that the capillaries in affected parts of the brain leak consipcuously within 90 minutes after administration of ''C. perfringens'' type D toxin.

 

diseases of sheep: a diagnosis can be established by histology of the brain, in which a characteristic focal symmetric encephalomalacia is seen.

==Treatment and Control==

==Treatment and Control==