Ark Veterinary Centre

Clostridial Diseases

Jan 8, 2020

1. Blacks Disease 2. Blackleg Disease 3. Tetanus 4. Botullism

1. Blacks Disease

Black disease is typically associated with migration of immature liver fluke and can affect unvaccinated cattle and sheep of all ages.

Clinical signs are rarely observed and cattle are simply found dead. There is no treatment for black disease. An appropriate fluke control plan, combined with an appropriate clostridial vaccination programme, will prevent black disease.

2. Blackleg Disease

Cases of blackleg often increase when animals are turned out or moved to new pastures, so be aware of the signs so that action can be taken to prevent further disease.

Clostridial spores can enter the body of an animal through skin wounds, and contaminated needles/injection equipment. Muscle trauma from bulling events in heifers and injuries at congested feed barriers trigger spore activation and lead to disease. Outbreaks of blackleg have been reported after earthworks such as field drainage, road construction, and exposure of earth floors during mucking out buildings, causing exposure to the highly resistant clostridial spores in the soil.

Affected cattle are often found dead. More typically, affected cattle are very dull and depressed, do not feed and have a very high rectal temperature (>41.0°). Involvement of one limb results in sudden onset severe lameness. There is obvious muscle necrosis at postmortem examination. Penicillin (44,000 iu/kg) is unlikely to be effective unless started in the very early stages.

 

Vaccination is essential where blackleg is a problem on the farm. The best protection is a two-dose course followed by annual revaccination.

3. Tetanus

Disease follows production of a powerful toxin which attacks the nervous system. Clinical signs are most frequent following puncture wounds or infection of the castration site following the application of rubber rings or contamination of the surgical site.

Affected calves show hind leg stiffness and difficulty walking. Animals stand with the legs abducted giving a "sawhorse" stance. They have an anxious startled expression with bulging eyes with the ears held back towards the poll, and flared nostrils. The animal is unable to open its mouth "lock jaw" and there is moderate bloat. Very often an infected animal will show a raised tail head. Despite treatment, in some cattle the condition progresses over two to five days such that the animal is unable to stand. Seizure activity is precipitated at first in response to loud noises then occurs spontaneously, followed by death from respiratory failure.

4. Botulism

Most sporadic cases of botulism in cattle have been associated with poultry litter spread onto pasture. The feeding of ensiled poultry manure and bakery waste has caused very serious losses in cattle on individual properties. Bird carcases in silage clamps have been implicated in some sporadic cases of botulism.

Botulism is caused by ingestion of pre-formed toxins of Clostridium botulinum where clinical disease varies from apparent sudden death to recovery after 14-21 days. Clinical signs are confined to the nervous system with muscle weakness affecting the hindlegs during the early stages with eventual recovery. More usually, weakness progresses over four to seven days to involve the forelegs, head and neck. Affected cattle have difficulty chewing and swallowing and there is paralysis of the tongue. Cattle must be euthanased at this stage for welfare reasons otherwise eventual involvement of respiratory muscles and diaphragm causes death.

 

 

 

 

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