Tetanus

Tetanus in Horses

Tetanus in Dogs

Also known as:

Lockjaw

Description

Tetanus is a rare disease in dogs. The disease pathophysiology is similar to that seen in the horse; the causal agent the neurotoxin of the gram-positive bacterium Clostridiu tetani. Infection occurs due to contamination of a wound by C. tetani and replication of the bacteria in the wound's anerobic environment. Tetanospasmin (neurotoxin) produced by the bacteria is transported to distant sites via the circulation and intraaxonally along peripheral nerves. This causes inhibition of the release of GABA and glycine from interneurons in the spinal cord and brain, resulting in tetanic spasm of striated muscle. Because of their high natural resistance to tetanospasmin, affected dogs may have a longer incubation period than that described in the horse. Dogs may often develop a localised tetanus rather than the generalised tetanus seen in other species.

Diagnosis

Clinical Signs

• Rigidity of the neck, trunk and limb muscles
• Hypersensitivity to external stimuli

The localised form of tetanus seen in dogs different clinical signs to those seen in the horse. Thh as displaying stiffness in a single limb combined with an obvious wound in the

• Cases may vary from mild signs of a short, stilted gait, to complete recumbency with spastic paralysis. Progression of the disease may lead to involvement of the pharyngeal and laryngeal muscles leading to aspiration pneumonia. Recumbency may be followed by paralysis of the respiratory muscles, leading to death due to hypoxia or respiratory arrest.

References

• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial