Two of the oldest recorded conditions in cattle are clostridial diseases such as blackleg and parasites.
I was chatting to a colleague last week about castrating weanlings as I had a big number to do that day on two farms.
He asked me was I going to treat them with penicillin in case they got blackleg.
I, conscious of the recent legislation to minimise prophylactic antibiotic use, said “no but I will give them painkiller. They are vaccinated for blackleg”.
One farm certainly had but the second farm had not.
Two nights later, I got a call from the second farm and my heart sank – a weanling was down. I arrived shortly after to find he had just died.
I examined him but could not find any evidence of blackleg.
A second weanling died the next day; he appeared to have scour.
The lab report shocked me – Type II Ostertagia.
Type II Ostertagia is where a portion of worm larvae enters the wall of the stomach in autumn and hibernates.
When a stress occurs in winter/spring, these larvae all emerge together causing rapid disease with sudden death common.
The era of Ivermectin had all but consigned this to history.
Resistance
However, recently with antiparasitic resistance, we are seeing treatment failure with all these groups of wormers.
Because the larvae were hibernating, the faecal samples from this farm came back negative after housing.
Obviously, the stress of castration had brought on the army of worm larvae.
Blackleg is straightforward to prevent with a multivalent clostridial vaccine.
The antiparasitic resistance on this farm will prove more difficult and will require a lot of time, FEC testing and pasture management.
Conor Geraghty MVB, XL Vets, Farmgate Veterinary Group, Galway
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