Clostridial Diseases

Botulism

Botulism is a lethal food poisoning in cattle caused by eating material that contains Clostridium botulinum toxins. Clinical disease may be seen in individual animals or as groups during outbreaks of disease (Kelch et al., 2000; Yeruham et al., 2003). The incubation period varies from a few hours to two weeks, making it difficult to identify the source of poisoned material eaten by affected animals. The most common manifestation of the disease in cattle is a subacute disease with restlessness, incoordination and difficulty swallowing which develops into recumbency, paralysis and death within 1-7 days.

The bacteria occur world-wide. In the UK, cases are likely to arise either due to:

• Ingestion of poorly fermented silage (allowing persistence of clostridia spores)
• Silage contaminated with soil
• Contact with animal carcasses or skeletons of dead animals containing the toxin.

The use of poultry litter as a fertilizer on grazing pastures or broiler litter as bedding material for livestock has been implicated as a risk factor, though the reasons are not fully understood (Hogg et al., 2011; Otter et al., 2006; Payne et al., 2011). Outbreaks of disease on a farm may have implications to human health as the fate of botulinum toxins in the food chain is not clear, therefore, restrictions on sale of livestock and milk from affected farms will be enforced (Cobb et al., 2002).

Blackleg

Blackleg infection is caused by Clostridium chauvoei and is almost always associated with infected wounds in cattle. Most cases occur in young stock between 10 months and two years of age. Feet or legs and the tongue are often the predilection site. Within 48 hours there is a high fever and if limb muscles are involved the animal becomes stiff and unwilling to move. Skin discoloration, subcutaneous edema and gas production may be present and perineal edema is sometimes seen. Infections of the head may produce marked edema and even bleeding from the nose. Death usually follows a period of anorexia, profound depression and prostration.

The spores of C. chauvoei survive well in the soil.

Tetanus

Tetanus is caused by the toxin tetanospasmin released from the spore-forming bacillus Clostridium tetani. The disease in cattle occurs most often after surgery or difficult calving after spores gain entry to a wound. Germination of spores occurs only if the microenvironment is anaerobic. After germination of the spores within the wound the C. tetani bacilli proliferate and produce toxins.

The incubation period can  vary from 3 days to several months but most cases occur usually after about 10 days. At first the animal appears slightly stiff, becomes unwilling to move and develops a fine muscle tremor. The temperature rise is variable (39 – 42° C). The general stiffness of the limbs, head, neck and tail (raised tailhead) increases after 12 – 24 hours. The animal shows hyperaesthesia and repeated spasms. Mastication becomes difficult due to tetany of the masseter muscle (lockjaw), food is chewed with difficulty, the animal drools saliva and bloat often occurs. There is retention of the urine and constipation. The animal becomes recumbent, with the legs rigidly extended, opistotonos and the jaws become rigid. The animal usually dies due to respiratory failure 3 – 4 days after the onset of clinical signs. Milder cases, which develop more slowly, can recover over a period of weeks or even months.

Bacillary Hemoglobinuria

Bacillary hemoglobinuria is a rapidly fatal disease caused by Clostridium novyi type D (also called Clostridium hemolyticum or Clostridium edematiens). The disease is associated with liver damage such as that caused by liver fluke. The condition is fairly rare in the UK. Cows that are inspected less regularly such as young stock or dry cows can be found dead. In lactating cows, a sudden drop in milk yield associated with high fever is seen. Other clinical signs include ruminal stasis with or without apparent abdominal pain, rapid breathing, dark red urine, jaundice and death within a short time of the onset of clinical signs.

Spores of C. novyi type D can be found both in the soil and in the livers of normal cattle on farms where the disease occurs.

Malignant Edema

Malignant edema is caused by the infection of wounds with any of several bacilli of the genus Clostridium (C. oedematiens type A; C. chauvoei; C. perfringens; C. sordellii; C. septicum). The condition is sporadic and fairly rare , but outbreaks involving several animals may occur after an event that has caused bruising or wounds (e.g. penning for a short period). Clinical signs appear rapidly and at the site of infection a swelling will develop which will ‘pit’ on pressure. Gas may be detected, as the skin becomes darkened and tenser. A high fever is present and toxemia develops. The animal can die within 1 – 2 days.

Control and Prevention of Clostridial Diseases

Vaccination

Since Clostridia are common in the environment, the most effective way of controlling clostridial diseases is by vaccination. Consult your vet to determine which vaccine is most suited to your farm to ensure best disease protection. Only healthy animals should be vaccinated.

If clostridial disease has been a problem on the farm, prevention should be included as part of the Herd Health Plan. Use of vaccine can also help prevent disease in young stock by passive transfer of immunity via antibodies in colostrum from vaccinated dams.

Additional Preventive Advice for Clostridial Disease

• Control of liver-fluke infection is an important step in the prevention of bacillary hemoglobinuria. Wounds may be treated with herbal or homeopathic remedies (Elliott and Pinkus, 1993) but it is important that wounds are exposed to air, as the organisms are anaerobes
• Attempts should be made to minimize all wounds and treat (with antimicrobials if severe) all those that do occur
• Good hygiene is essential at castration and assisted calving docking
• Careful handling is important as bruising may cause blackleg
• Clean needles and a clean, dry injection site are important if the animals are to be injected as penetrating wounds may cause tetanus
• Try to avoid soil contamination of silage and ensure good fermentation to pH 4, to kill clostridia
• Avoid late surface spreading of slurry as this predisposes to poor silage fermentation (Laws et al., 2002)
• Ensure cattle feed and water are not contaminated by carcasses (such as small rodents) or feces
• Don’t use poultry litter as a surface soil conditioner on land that will be used for grazing or conservation of forage. Instead, it should be ploughed into arable land.

Treating Clostridial Diseases

Professional advice should be sought regarding whether or not clinical cases infected with clostridia species should be treated or humanely euthanized.

Treatment of bacillary haemoglobinuria with penicillin can be attempted. Treatment of clinical blackleg has met with little success. Treatment of malignant edema can also be attempted with antibiotics and local treatment of the wound with hydrogen peroxide or other oxidizing disinfectants.

Treatment of botulism carries a poor prognosis and attempts at treatment depend of the severity of clinical signs at presentation. The use of intra-venous glucose saline and administration of ruminal fluid was reported as successful in treatment of less severe cases (Braun et al., 2005).

Treatment of tetanus cases is difficult and the response is usually poor. Full doses of antibiotics such as products containing penicillin can be administered to eliminate the bacilli, but further toxin prevention can only be achieved by surgically removing the port of entry, usually a wound. . Tetanus antitoxin should also be given. Success often depends on good nursing with forced feeding (via stomach tube) if necessary. If the infected wound can be found it should debrided and treated with hydrogen peroxide. Sedation and reduction of muscle tetani, to avoid asphyxia, can also be attempted.

Clostridial Disease and Welfare

If there is a known problem with clostridial disease on the farm, the animals must be vaccinated so as not to compromise the health and welfare of the animals. In suspected cases of affected animals, veterinary advice must be immediately sought. Your vet has to decide whether or not clinical cases infected with clostridia species should be treated or humanely destroyed.

Good Practice Based on Current Knowledge

• If there is a known problem with clostridial disease on the farm, the animals must be vaccinated
• The veterinary surgeon must decide whether a case is worth treating or must be humanely destroyed to prevent further suffering
• Liver fluke must be kept under control to prevent bacillary hemoglobinuria.
• Good hygiene should be maintained during calving and castration. Any wounds should be treated with conventional and/or alternative methods
• Careful handling of the animals is important to prevent bruising.