Course: Diseases and pests in cattle | Last Updates: 7th October 2015
During 2006 the average numbers of deadstock per farm registered with the fallen stock scheme was five young cattle and six sheep. A further 207,000 adult cattle were screened for BSE after having been collected as fallen stock. It's a sad truth that where there's livestock there will always be deadstock, but it would be wrong to assume nothing can be done to reduce these losses.
A massively underestimated cause of sudden deaths is one of the oldest bacteria of them all – clostridia. They are spread throughout the world and take the lives of cattle, sheep and most other farm livestock on a daily basis.
The life cycle
Clostridia are a family of bacteria that have a rather unusual method of surviving when conditions don't suit them. They form protective spores to survive in soil and within body tissues and only emerge when conditions are right for their rapid growth.
Clostridia are closely related to another spore forming family of bacteria that include the deadly cause of Anthrax. Spores of Bacillus anthracis have been shown to survive for several decades in soil.
To emerge from their spores and start multiplying, most forms of clostridial bacteria prefer a reduction in oxygen supply. This sometimes occurs when cattle are bruised or injured and when clostridia are present in the region of bruised tissue they rapidly multiply, producing potent and dangerous toxins.
But it is the toxins that cause real damage by destroying muscle tissues. These potent neurotoxins cause the animal's muscles to become paralysed and stiff. In cattle the tail is usually raised a little and often the animal can't feed itself due to the classic lock-jaw effect on the cheek muscles.
There are lots of different diseases caused by the various combinations of clostridial toxins – braxy, blackleg, and botulism. Anyone who has been unfortunate enough to have heard these disease names before is also likely to know they all kill quickly.
One of the mysteries of the clostridial family remains how to predict when a problem might occur. Certainly when animals are grazing tightly they are likely to consume some soil, so risk increases. Deep wounds in poorly oxygenated areas and internal damage such as ulcers in the gut can also allow clostridia to multiply and cause further damage.
Clearly not many of these risk factors can be controlled. However, it is worth bearing in mind that common procedures such as disbudding, castration and vasectomising bulls or tups can open up an animal to the threat of infection with clostridia. Also sudden feed changes that may lead to rumen acidosis could also be a problem.
Control of clostridial diseases
Wherever livestock are farmed it's important to consider the risk of clostridial infection and disease. With replacement animals being a costly consequence, deaths of any productive animal will significantly affect farm profits. Nowadays there is the additional hassle and cost of disposal of carcasses.
Any risk associated with surgery can be reduced through the use of antibiotics. A quick dose of long-acting penicillin after any surgery that breaches the skin adds a small amount to the cost of a castration or vasectomising job, but could be a sensible investment in the long run. Longer term control involves the use of one of the range of clostridial vaccines.
Almost all clostridial vaccines contain a mixture of several components, sometimes including elements of the toxins themselves. Multicomponent vaccines are common use in breeding sheep, but uptake of vaccination for cattle is much less common. Only a small percentage of our farmers think about the importance of clostridal vaccines. Yet every year several lose stock to blackleg in particular.
Recent developments in vaccine technology have led to the introduction of a new 10-way vaccine that delivers potent protection in an exceptionally small dose. For cattle producers this product represents a reliable risk control strategy and seems to make good commercial sense. You have to look at the cost of regular vaccination and compare that with how many cattle may be lost through time.
Saving one finished beast will pay for 500 courses of vaccine and that's not including the hassle and cost of disposal of deadstock.
So next time an animal is unexpectedly found lying dead appearing to have blown up quickly or started to decompose rather fast, then consider if clostridia could be involved. In New Zealand the grass-based systems make clostridial vaccination just as common in cattle as in sheep and with the value of cattle rising steadily in this country it must surely be time to consider investing just a little more time and money to secure herds for the future.
A recent survey of 521 UK dairy and beef farmers, commissioned by SPAH, revealed:
- 58% of the respondents experienced calves or cattle dying for no apparent reason
- 49% of cattle dying for no apparent reason have had a case in the past 12 months
- The number of animals lost by those surveyed is 2.6 animals
- Each animal death cost an estimated £958 (ranging from £505 to £1243).
Of those farmers who have had an animal die as a result of a clostridial disease, the following diseases/pathogens were implicated:
- Blackleg – 59%
- Unidentified clostridial disease – 21%
- Tetanus – 9%
- Botulism – 3%
- Gas gangrene – 3%
- Haemorrhagic scour – 2%
- Bacterial Redwater – 0%
- Black Disease – 0%
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