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EVOLUTION

ANIMAL BREEDS

DISEASES

MEDICATIONS

FOOD/FEED

BEHAVIOUR

EXOTIC ANIMALS

SPECIAL SECTION

Bacterial Disease - Botulism

Synonyms

Equine grass tetany, Equine dysautonomia, Limber neck and Shaker foal syndrome.

Etiology

Clostridium botulinum is a spore (oval, sub terminal endospores) forming, gram positive organism, appears as single/paired/short chain.

Epidemiology

Prevalence of infection Spores survive in the environment for long period. The disease is distributed worldwide, including India.

Predisposing factors Heat and moisture favors the germination of spores.

Source of infection

The proliferation of organism occurs in decaying vegetable or animal matters. The toxin is stable particularly in bones. In sheep, due to dietary deficiency of protein or net energy.

Transmission

The spread of infection by ingestion of contaminated material or birds or blow flies are possible.

Spread of infection through injury.

Host affected

Cattle and sheep are susceptible for type C and D while horses are susceptible for type B toxin.

Pigs, dogs and cats found to be resistant.

Human is also susceptible for bolutinum toxins.

Pathogenesis

Botulism toxins are neurotoxins absorbed by the intestinal tract or the wound and traverse through the blood stream to peripheral cholinergic nerve terminals and neuromuscular junction, post ganglionic parasympathetic nerve endings and peripheral ganglia.

The toxin has heavy chain bind to the receptors and translocated into the cells and the light chain of the toxin blocks the release of acetylcholine at the neuromuscular junction/motor nerve endings.

Toxins produce functional flaccid paralysis.

Animal dies due to respiratory paralysis.

Clinical findings

Early muscle tremor,

progressive symmetrical weakness,

motor paralysis leading to recumbency.

Mydriasis,

ptosis,

weak tongue retraction

sensation and consciousness retained until death

Necropsy findings

None specific

Diagnostic confirmation

Demonstration of toxin in serum or feed. Demonstration of organisms in feed, intestinal contents or wounds

Differential diagnosis

Ruminants

  • » Parturient paresis in cattle.
  • » Hypocalcaemia in sheep.
  • » Tick paralysis.
  • » Rabies.
  • » Organophosphate or carbomate poisoning.
  • » Louping ill.

Horses

  • » Equine protozoan myelitis.
  • » Equine encephalomyelitis.
  • » Hepatic encephalopathy.
  • » Rabies.

Treatment

Type-specific antiserum and supportive treatment

Control

Avoidance of exposure by feed management and Vaccination.

Zoonotic implications

Botulinum toxin is identified as a possible agent for bioterrorism. The meat and milk from cattle that have botulism should not be used for human consumption.


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