Strange Deaths in Cattle – What’s Killing Your Herd?

As autumn is now truly underway there are some causes of sudden death in cattle to be aware of. Sudden death in cattle is always a cause for concern on a farm and can be a distressing event. Here we present some of the major causes, how to identify them and how to approach each situation in a calm manor.


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Anthrax is a notifiable disease in cattle, however it is extremely rare in the UK, with the majority of global cases seen in Central and Southern America. The last reported case of anthrax in the UK was 2006. Anthrax is a soil-borne bacteria, the infection can result in sudden death, often seen with a bloody discharge from the nose and mouth. Yet the standard treatment for anthrax, if detected early enough, is a course of antibiotics. Anthrax bacteria can stay dormant in the environment for a long time – the spores are formed when the bacteria is exposed to air.

Grass Staggers

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Magnesium deficiency in a cow can lead to grass staggers (hypomagnesaemia). This results in increased excitability, muscle spasms, seizures, collapses and sudden death. Consequently, dead animals are usually found with visible signs of trauma, often covered in mud from thrashing about prior to death. Grass staggers is most likely to occur in the spring and autumn when grass nutrient levels are low. The best course of treatment is to administer magnesium subcutaneously at multiple sites on the animal. Unfortunately if the animal is already experiencing seizures and/or thrashing about they are likely to die either before treatment is administered or shortly afterwards. Magnesium enriched salt licks are a good way to supplement diets in the spring and autumn when grass staggers is more likely to develop. This disease is most common in summer suckler cows with calves. To prevent this disease, manage your spring grazing.

Clostridial diseases

Clostridia are a class of bacteria commonly found in soil and other environmental samples. The class of bacteria is made up of multiple different species and strains. Clostridial infections are fairly common in the UK and are a cause of sudden death in cattle. Each species and strain cause a variety of diseases, some of which result in sudden death. Some common clostridial diseases are listed below:

  • Blackleg (severe lameness, marked depression)
  • Botulism (muscle tremors, weakness, paralysis)
  • Pulpy kidney (excitement, incoordination, convulsions)
  • Tetanus (stiffness, tremors, lockjaw, collapse, spasm)
  • Enterotoxaemia (rectal prolapse, flatulence, diarrhoea)
  • Black disease (clinical signs rarely seen)

Clostridial diseases are often difficult to successfully treat, therefore prevention is much more appropriate. However multiple vaccines are available for cattle that cover multiple different clostridial strains. Read more here.


Cattle that are fed too many highly digestible carbohydrates like barley and concentrates, can develop acidosis and bloat. The gas collects in the rumen and if not treated quickly can result in collapse and death due to excessive pressure on the diaphragm and lungs. The gas needs to be released quickly by either passing a stomach tube into the rumen or using a cannula to puncture a hole through the side of the rumen. Once the bloat has been removed the pH in the rumen needs to be corrected by administering oral alkaline antacids.


Both cattle and calves can suffer with pneumonia. It may cause progressive deterioration and sudden death and Signs usually include a fever, dullness, inappetence, increased respiratory rate and a ‘’snotty’’ nose. Early treatment with appropriate antibiotics can resolve clinical signs. 

Fog Fever

Fog fever typically occurs in autumn when cattle move to fresh pastures with high grass protein levels. The high protein levels result in a respiratory condition that makes it hard for them to breathe, increases coughing and/or causes frothing at the mouth. Currently there are no treatments solely for this condition but anti-inflammatories can help reduce clinical signs. 







toxins causing cattle death
Pictured is Conium Maculatum, otherwise known as Hemlock.

Cattle are naturally very inquisitive animals. This can lead to them eating compounds they shouldn’t. This includes toxic plants such as yew and hemlock, nitrate poisoning from brassicas and green cereals, and lead poisoning from batteries. All of these toxins can cause sudden death so it can be useful to check field boundaries for toxic plants and also check no one has dumped rubbish onto the pasture being grazed. Sudden death in cattle is one of the most shocking things to find when checking stock, and whilst not all causes can be prevented you should take the following steps to ensure that sudden death in cattle is avoided:

  • Regular maintenance of field borders and hedgerows
  • Good biosecurity on and off premises
  • Monitoring /restrict fresh grass and feed intake
  • Regular animal checks
  • Diet supplementation

Written by Joseph Payne.