It is the peak season for pulpy kidney in the next few months. Clostridial vaccines are good but transfer of antibodies to lambs relies on good colostrum intake. Beware the immunity gap if lambs have not received two doses of vaccine before colostral protection wanes.
Diagnosis is not always straightforward as post mortem findings and test results can vary from case to case. History and post mortem findings should be looked at in combination with any test results. You need to be confident in your diagnosis particularly if you are going to introduce vaccination or make changes to existing protocols as a result.
Post mortem findings – some of the following may be found:
- Serous effusions into body cavities - particularly an increase in pericardial fluid which may contain a fibrin clot.
- Congested/oedematous lungs with froth in the airways – you may be suspicious of pasteurellosis.
- Pulpy kidneys – this is just autolysis so unless the carcase is very fresh this finding can be very subjective. Compare the degree of kidney autolysis to other organs such as the liver.
- Cerebellar coning – swelling of the brain can cause the caudal cerebellum to be forced into the foramen magnum giving it a slightly pointed appearance.
The following testing options are available and each has pros and cons. Most are not diagnostic in their own right.
- Bacteriology – anaerobic culture of ileum for Clostridium perfringens. This is a commensal bacteria and therefore not diagnostic.
- Clostridial toxin testing – ELISAs are carried out on small intestinal contents. We cannot test tissue samples such as liver, kidney or spleen. The ileum is the best site to collect a sample and for pulpy kidney request epsilon toxin testing. Be aware that small amounts of toxin may be present in lambs that have died of other causes. It can also be produced (or disappear) after death. Confirmed cases of pulpy kidney can be either positive or negative for epsilon toxin.
- Test urine for glucose – collect urine into a red top tube using a vacutainer needle. Glucosuria can be detected in some cases of pulpy kidney. Post mortem growth of bacteria in the urine can destroy any glucose present.
- Histopathology – Kidney can be examined for changes including renal tubular degeneration. The histopathologists like to examine kidney in addition to other tissues, e.g. liver or lung, as they can then compare the degree of autolysis. The cost is the same whether 1 or 3 tissues are examined – and if it’s not pulpy kidney you might get a different diagnosis. Examination of kidney is not always diagnostic.
- Brain histopathology – The reward for making the effort to remove the brain could be a confirmed diagnosis if lesions of focal symmetrical encephalomalacia are detected.
Where geography and time permit, delivery of one or more lambs to the lab can be more cost effective and due consideration of other possible diagnoses can be made.