MANY parts of Victoria seem to be on the way to a good spring, but unfortunately good conditions sometimes produce the most worries, warns a leading Department of Environment and Primary Industries’ (DEPI) vet.
With abundant spring growth, livestock losses due to enterotoxaemia and bloat become a definite possibility, Dr Jeff Cave, district veterinary officer at DEPI Wodonga, said.
Enterotoxaemia is caused by a toxin produced by Clostridium bacteria, which is found in the bowel of normal cattle and sheep.
Enterotoxaemia occurs when a large amount of readily fermentable feed is present in the bowel leading to rapid multiplication of the bacteria and a lethal level of toxin production.
Due to the rapid progression of the disease, an animal affected by enterotoxaemia will usually be simply found dead in the paddock. On post-mortem rapid decomposition of the carcass is seen.
Young stock in good condition up to two years of age are most commonly affected, however deaths may occur in older stock.
Little can be done to treat an animal affected by enterotoxaemia, therefore the emphasis should be on prevention, Dr Cave said.
“The key to prevention is to ensure livestock are adequately protected through vaccination.
“As with any vaccination program adult cows and ewes should be vaccinated approximately one month prior to calving to give their calves and lambs maternal or passive immunity through the colostrum.
“Passive immunity lasts approximately six weeks after which calves and lambs need to be vaccinated to gain active immunity by two injections at least four weeks apart.”
Most vaccines give 12 months' protection, so should be then given annually. A feature of the enterotoxaemia vaccine is the duration of immunity it provides may be quite short – it may only give three or four months of protection, Dr Cave said.
“Therefore a booster dose should be given before a high-risk period, for example, at the beginning of spring,” he said.
