Polioencephalomalacia (PEM, Polio)
What is Polio?
Polio occurs occasionally in young cattle and sheep. Affected animals may present with one or more of the following signs:
- Depressed, dull, lethargic
- Standing alone in the paddock and frothing at the mouth
- Down, thrashing their legs
- Some may even appear blind or press their head against objects.
Polio is a disease which affects the brain, which leads to the nervous system signs we see; blindness, head-pressing etc. The brain damage (lesions) observed is associated with thiamine deficiency or a disturbance in thiamine metabolism. This may be from a toxin that has been eaten, or from the bacteria in the gut which produce thiaminase (an enzyme which breaks down thiamine).
What can cause Polio?
- Calves in good condition that are exposed to an abrupt change in diets, leading to an increase in thiaminase production and secondary deficiency of thiamine.
- Concentrate fed animals not consuming enough roughage.
- Feeding of milk supplement which lacks adequate thiamine.
How can we treat the problem?
If the disease is identified early, there is usually a rapid response following treatment with thiamine (Vitamin B1).
It is important not to assume that this disease only affects one calf in the mob. Surveillance of the affected mob for the next 24-48 hours is necessary as others may show similar signs.
Prevention of Polio.
There are a few things we can do to prevent polio being a major problem.
- Prevent rapid changes in diet.
- Ensure adequate (>50%) roughage in diet.
Under some special circumstances you may need to consider the addition of thiamine to your supplementary feed (grain or pellets).
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