A Complete Guide to Botulism in Cattle

Botulism is a severe, often fatal disease of cattle caused by toxins produced by the bacterium Clostridium botulinum. Unlike many other clostridial diseases, botulism does not usually result from bacteria multiplying inside the animal’s tissues. Instead, cattle develop the condition after ingesting pre-formed toxins present in contaminated feed, water, or soil.

Although relatively rare in the UK, botulism can occur under certain conditions and may result in significant herd losses. This guide provides everything cattle farmers need to know about botulism: its causes, symptoms, diagnosis, treatment, and, most importantly, prevention.

What is Botulism?

Botulism is caused by toxins produced by Clostridium botulinum, a spore-forming bacterium that:

• Is widely present in soil, faeces, and decaying matter.
• Survives for years as hardy spores.
• Produces toxins under anaerobic (oxygen-free) conditions, such as in decomposing carcasses, spoiled silage, or rotting vegetation.

Cattle are not infected directly with the bacteria. Instead, they ingest the pre-formed botulinum toxin, one of the most potent naturally occurring toxins known.

Once absorbed into the bloodstream, the toxin interferes with the transmission of signals between nerves and muscles. This results in paralysis, which progresses to respiratory failure and death.

Causes and Risk Factors

Botulism outbreaks in cattle are usually associated with ingestion of toxins from contaminated feed or environment:

• Spoiled silage or haylage: poorly fermented or inadequately stored silage may harbour toxin.
• Carcass contamination: dead animals (e.g. birds, rodents, or small mammals) accidentally baled into silage or contaminating feed and water.
• Poultry litter: in some countries, poultry litter used as cattle feed or fertiliser is a well-recognised source of toxin.
• Decaying vegetation: rotting organic matter in feed troughs, bale wraps, or storage areas.
• Water sources: stagnant ponds or troughs contaminated with decaying matter.

Risk increases in intensive or housed systems where silage or haylage is a major feed source.

Symptoms of Botulism in Cattle

The onset and severity of disease depend on the amount of toxin ingested. Symptoms typically appear within hours to several days.

Common signs include:

• Weakness and progressive paralysis.
• Difficulty swallowing.
• Loss of tongue strength – cattle may be unable to retract their tongue when pulled out.
• Drooling and reduced ability to eat or drink.
• Poor coordination, staggering, and eventual recumbency (lying down and unable to rise).
• Flaccid paralysis of limbs.
• Death due to respiratory failure.

In mild cases, recovery may occur over several weeks, but most affected animals die within a short time.

Diagnosis

Diagnosis of botulism can be challenging because clinical signs resemble other neurological diseases.

• History: recent feeding of silage, haylage, or potentially contaminated feed.
• Clinical signs: flaccid paralysis, loss of tongue tone, drooling.
• Laboratory confirmation: toxin detection in feed, water, or serum samples, though this is technically difficult and not always available.

Because post-mortem findings are usually non-specific, diagnosis is often based on history and signs rather than laboratory tests.

Treatment

There is no specific cure for botulism once signs develop.

• Antitoxin may neutralise circulating toxin if administered very early, but it is not widely available for cattle in the UK.
• Supportive care: nursing, fluids, and careful feeding may help mildly affected animals, though recovery is slow.
• Severely affected cattle usually die or must be euthanised for welfare reasons.

As treatment is rarely successful, prevention is the only reliable strategy.

Prevention

Feed and Forage Management

• Ensure silage and haylage are well-fermented, properly sealed, and free from spoilage.
• Do not feed visibly mouldy or spoiled silage.
• Inspect feed for carcass contamination and dispose of suspect material.
• Avoid feeding silage from poorly wrapped bales or clamps exposed to air.

Carcass Management

• Remove dead animals promptly from pastures, sheds, and feed stores.
• Prevent access of cattle to decaying carcasses in fields or water sources.

Environmental Hygiene

• Keep water troughs clean and free from debris.
• Avoid using poultry litter as fertiliser or feed unless thoroughly treated and safe.
• Maintain clean housing and feed storage areas.

Vaccination

• In the UK, botulism vaccination is not routinely practised because the disease is uncommon.
• In areas where poultry litter is widely used, or where botulism is endemic, vaccination may be recommended.
• Farmers should consult their vet about whether vaccination is appropriate in their region or system.

Economic and Welfare Impact

• Welfare: Botulism causes progressive paralysis, inability to eat or drink, and eventual respiratory failure – making it a major welfare concern.
• Economic: Outbreaks can result in the sudden loss of multiple cattle, disposal costs, and reduced productivity.
• Prevention vs cost: Careful feed management and hygiene are far more cost-effective than dealing with an outbreak.

When to Seek Veterinary Help

Contact a vet immediately if:

• Multiple cattle show weakness, drooling, or paralysis.
• Deaths occur suddenly after feeding silage, haylage, or other feed.
• You suspect feed contamination.
• You need guidance on botulism vaccination or prevention.

Conclusion

Botulism in cattle is a rare but devastating clostridial disease caused by ingestion of pre-formed toxins from Clostridium botulinum. It results in paralysis and rapid death, and once signs appear, treatment is almost always unsuccessful.

For UK farmers, prevention is key. Maintaining strict feed and silage hygiene, removing carcasses promptly, and working with a vet to assess risks are essential steps. With good management and vigilance, the risk of botulism can be greatly reduced, protecting both animal welfare and farm profitability.