The New Zealand Veterinary Association (NZVA) is working closely with the Ministry for Primary Industries (MPI) and Fonterra on the impact of Fonterra's whey protein contamination issue.
NZVA working group
An NZVA working group has been formed to monitor and follow the progress on this matter, and to liaise with key stakeholders. At this stage, the group is meeting daily and is in regular contact with MPI and Fonterra. We'll provide updates as necessary by ezine, twitter and on the NZVA website www.nzva.org.nz
For more information on the impact of whey protein contamination in other products, please visit the MPI website
As this issue is of national and international significance, MPI will coordinate all media activity. All media enquiries should be directed to the MPI media team on 029 894 0328.
Botulism in cattle
The focus of this message is “botulism in cattle” brought to you by the NZVA’s Society of Dairy Cattle Veterinarians.
Clostridium botulinum is an obligate spore-forming anaerobe with the spores being resistant up to 120 degrees C. The bacteria rarely cause a primary infection.
Cattle of all ages can be affected by botulism. Botulism has been reported in a number of species of birds in New Zealand and rarely in dogs. The disease is caused by a neurotoxin produced by Cl. botulinum bacteria, an intoxication rather than infection. This results from cattle consuming toxins in contaminated feed or water. Botulism occurs in cattle in Australia and many other countries where the source of neurotoxins may be:
- Ingesting toxins from carcasses or from feed or water being contaminated by rotting organic matter (eg. dead birds in grain silos or ensiled feeds) or from pica due to hypophosphataemia
- Chicken manure used as fertiliser which may contain chicken carcasses.
Different types of Cl. botulinum and clinical signs
Neurotoxins are heat-labile and are destroyed by boiling. There are seven types of Cl. botulinum classified according to the antigenicity of their toxin with different types being more important in different host species. Type C and D toxins are most common in cattle with botulism.
The latent period from time of exposure to the toxin to the development of clinical signs can be 12 hours to 14 days, or longer. Often multiple animals are affected in an outbreak.
Clinical signs result from the inhibition of the release of acetylcholine causing a flaccid paralysis.
Disease types and symptoms
- Peracute disease – where high levels of toxin are ingested: flaccid paralysis and sudden death due to respiratory failure.
- Sub-acute disease – the muscles of the head are affected initially with flaccid paralysis of the tongue resulting in the animal being unable to swallow or retract the tongue back into the mouth after it has been pulled out for examination. Flaccid eyelids and dilated pupils can also be seen. The muscles of the hindlimbs are then affected before the forelimbs, resulting in muscular weakness, incoordination, staggering gait and recumbency. Affected animals may also have bradycardia, decreased ruminal motility and constipation. Duration of the illness depends on the amount of toxin ingested and may be a few hours to days to weeks. Usually, a number of animals will be affected.
- Other clostridial causes of sudden death
- Spinal cord disease
- Organophosphate poisoning.
Cl. botulinum is ubiquitous so isolating the organism from potential sources is not diagnostic. Isolation requires anaerobic culture.
Definitive diagnosis is achieved by demonstrating the toxin in suspected feed or serum of affected animals.
Animals that are only mildly affected may recover. When large amounts of toxin have been ingested and clinical signs develop rapidly and are severe then death is inevitable.
No specific treatments are available. Mild cases may recover with intensive support, but recumbent animals should be euthanased.
Animals that die from botulism are a risk for other livestock and need to be buried with at least three metres of soil on top and in clay or plastic-lined pits and well away from water sources. Off-farm rendering may also be considered.
If you have questions about this please contact us at Otautau Vets Ltd 03 225 8134