AS A final-year veterinary student on rotation with the district veterinarians on the NSW North Coast, I found it interesting that there was a recent increase in the number of cases of blackleg in the region and that they were being reported on farms that previously had not been affected.
Why did this occurr and what can be done to prevent it?
Blackleg is a common bacterial disease on the Mid- and North Coast. It usually affects fast-growing, young cattle, between four months to two years of age.
It is commonly seen in winter and spring; however, the increase in the number of cases and abnormal distribution of disease currently being reported is most likely due to the recent floods, which bring the bacteria to the surface of the soil and move it to new areas where, previously, it had not been found.
The blackleg bacteria can remain in the soil for years and are taken up by the cattle grazing on the pasture.
When the animal gets a bruise to an area - perhaps from yarding or play fighting - the bacteria stop in this area and produce gas and a toxin that damages the surrounding muscle and makes the animal sick.
In the early stages, an affected animal becomes lame with swelling of a muscle, stops grazing or appears sick and quickly goes down.
However, these signs are usually of such short duration they may be missed and more frequently the animal is found dead - typically on their side with the affected limb extended.
The good news for cattle producers is that blackleg can be easily and effectively prevented by vaccination, such as 5in1 or 7in1. Vaccinated pregnant cows can provide protection to calves up to 8-10 weeks of age. Calves should then be vaccinated from two months of age in two doses, four to six weeks apart. Boosters every 12 months maintain protection.
On another issue, it is also important to think about fluke control at this time of year. The most crucial time to drench for fluke is now: the April/May drench is essential.
It is important the drench used at this time targets immature fluke, usually an oral drench containing triclabendazole or something similar.
Liver fluke infections vary from district to district. If you are unsure if you have fluke on your property, contact your district veterinarian who can perform blood tests to determine if your cattle have been exposed to liver fluke, which will avoid unnecessarily drenching cattle for fluke.
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