Farmer loses five cows to botulism veterinary laboratory investigation concludes
Late last year Sligo Regional Veterinary Laboratory (RVL) received two cows for autopsy with a history of recumbency, frothing and paralysis.
The animals had been euthanased as there was no response to treatment.
There were three further dead cows with similar clinical history on the farm.
On autopsy, both animals presented similarly with watery, haemorrhagic (blood) contents in the small intestines and stomach.
According to the RVL report, there were no other significant lesions. Both cows presented with a heavy rumenfluke egg burden.
As both animals were freshly euthanased before submission, ruminal and intestinal contents were sampled and used for Clostridium botulinum testing.
In consideration of the history, nature of the outbreak, gross findings and histopathological lesions the RVL said it is likely that botulism is responsible for disease and death in these animals.
It said the presence of the toxin was not proven so this conclusion is based on the history, clinical signs and absence of an alternative diagnosis.
"In many cases, for various reasons, toxin is not detected.
"It should be remembered that very small amounts of toxin are fatal in ruminants and that identification of a potential toxin source, together with classic clinical signs of progressive flaccid paralysis, are often crucial to achieving a diagnosis," he said.
Botulism is a frequently fatal disease caused by ingesting C botulinum toxin and has been described in most animal species including humans.
There are seven types of botulinum toxin recognised (types A, B, C1, D, E, F and G), which are produced by the bacterium under certain environmental conditions. Exposure to poultry litter is a risk for the botulism in cattle, as is access to decaying wildlife carcasses.
Very small quantities of risk material (as little as a gram) may cause botulism because the toxic dose for animals is minute.
Clinical signs of botulism in cattle include: progressive weakness, posterior ataxia, progressive flaccid paralysis, tail flaccidity, protrusion or weakness of the tongue, drooling, prostration and death.
Death may be acute or sudden and clinically affected animals are generally bright and alert.