Sudden death – a timely reminder about clostridial diseases

Across southern Queensland, producers are stocking winter forage crops with young, rapidly growing cattle. Although all animals can be affected by clostridial disease, young cattle are at greater risk due to marking, management and eating lush growing pasture or grain.

Clostridial diseases are caused by Clostridium bacteria. These bacteria are normally found in soil and faeces, where they form highly resistant spores that can survive for a very long time. They are also present in the gastrointestinal tract and tissues of healthy animals. All clostridia are anaerobic, which means they survive and grow in environments with no or low oxygen supply.

Although not all clostridia cause disease, those that do usually kill the animal. Disease can occur when these bacteria enter the body and conditions allow them to multiply and/or produce toxins.

This article looks at the major clostridial diseases of cattle in Australia (excluding botulism) — tetanus, malignant oedema, blackleg, pulpy kidney and black disease.

More information on botulism is available on the FutureBeef website.

Tetanus, Clostridium tetani

Animals affected by tetanus have a stiff body, with their tail and neck stretched out, nostrils flared and third eyelid showing across the eye. As the tetanus progresses the animal will develop a “sawhorse” position and “lockjaw”. The animal will begin convulsions and eventually die of respiratory failure.

Tetanus is likely to occur where there is contamination of deep wounds. This includes wounds caused by marking procedures (castration, ringing and de-horning), dog bites and grass seed punctures. Clostridium tetani multiply and produce toxins that affect the central nervous system. These toxins impact nerves and muscles, causing rigidity and muscle spasms.

Malignant oedema, Clostridium septicum

Similar to tetanus, malignant oedema enters the body via wounds contaminated by soil. Castration and calving injuries pose the greatest risk of infection to calves and breeders. Toxins are produced at the entry wound, causing extensive swelling and a bloody or clear fluid. Tissue death and gangrene follow, causing extreme pain. As the infection progresses, toxins are absorbed into the bloodstream where they induce fever, weakness and death.

Blackleg, Clostridium chauvoei

Blackleg mostly affects young, rapidly growing cattle, particularly those between 6 months and 2 years old. As such, it is often high-value cattle in forward condition that are affected. Losses can occur in adult cattle but are less common. Blackleg tends to occur where there is abundant lush green feed, and the increased carbohydrate load enhances bacteria growth. The name ‘blackleg’ comes from the dark colour of affected muscle at the infection site. The infection originates from contaminated feed or soil, with Clostridium chauvoei spores entering the bloodstream and lodging in organs and tissues throughout the body. The spores can remain there until they are stimulated by a mild injury. A lack of blood flow and oxygen to the injury area causes the spores to multiply and produce toxins. These toxins destroy the surrounding tissues and enter the bloodstream, resulting in acute sickness and rapid death.

Signs of blackleg in cattle include not grazing, lameness with muscle swelling and appearing sick or going down. These symptoms do not usually last long and typically an animal is found dead with gas under the skin. Carcasses usually appear bloated and frothy, with blood-stained discharge from the mouth, nostrils and anus.

Do not open carcasses of animals suspected to have died from blackleg as this can release bacteria that will infect other cattle. Do not drag the carcass across the ground. If possible, burn or deeply bury the carcass where it lies.

Enterotoxaemia (pulpy kidney), Clostridium perfringens

Clostridium perfringens inhabits the intestine, although usually in low numbers. Under normal conditions, these bacteria produce a small amount of toxins, which are removed by normal gut movements and inactivated by antibodies.

Pulpy kidney can affect cattle of all ages, and is also seen in sheep, goats and other ruminants. Similar to blackleg, it occurs when there is a change in diet and an increase in carbohydrates (grazing lush green pastures and cereal crops, or heavy grain feeding). This enables the bacteria to multiply faster than the body can remove or neutralise it, causing toxaemia. This acute poisoning means often there are no signs of illness in the stock. They are simply found dead, with no signs of struggle.

Treatment for acute cases of enterotoxaemia is not successful due to the rapid development of the disease and extensive damage caused by the toxin. Animals with a less acute form of the disease become dull, docile and appear to be blind. In most of these less acute cases, animals will recover within 2 to 3 days.

Black disease, Clostridium novyi

Black disease, or infectious necrotic hepatitis, is an acute infection caused by Clostridium novyi. Black disease is associated with liver damage caused by liver fluke. This damage allows the bacteria to multiply and produce alpha toxin, which causes liver necrosis. Typically, death is sudden, but clinical signs include, constipation, lethargy, recumbency and lack of appetite. There is no treatment for black disease.

Preventing clostridial diseases

Clostridial disease prevention relies on the proper use of vaccines to promote immunity and management practices that reduce animal exposure to the causes of the disease. The 5-in-1 vaccine contains antigens of the five clostridium diseases covered here but does not protect against botulism and leptospirosis.

It is important to note that in most cases, a single vaccination does not provide adequate protection to clostridial diseases. It must be followed by a second dose within 4 to 6 weeks, ideally before weaning. Previously unvaccinated stock should receive two doses 4 to 6 weeks apart. Be sure to read the label to ensure correct dosage and administration. For more information on beef cattle vaccinations, visit the Vaccinations for beef cattle and Principles of using vaccines pages on the FutureBeef website.

Hygiene practices are crucial when it comes to preventing clostridial disease, especially when dehorning or castrating cattle. It is important to ensure all equipment is clean and free of blood, hair and soil. All instruments should be washed thoroughly before being soaked in a disinfectant.

In addition to maintaining and preparing equipment, avoid castrating and dehorning cattle in wet, muddy conditions, extremely hot and dusty conditions and when fly numbers are high. Use a powder containing fly repellent if dehorning during warmer months.

More information

Diagnosing clostridial diseases requires assistance from a veterinarian. If in doubt about the cause of cattle deaths, consult your veterinarian.