Changes

==Description==

==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.  

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 anerobic conditions provided by damamged and necrotic tissues. 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 persistent rigidity of striated muscle. Because of their high natural resistance to tetanospasmin (compared to the horse and man), affected dogs may have a longer incubation period and clinical signs may be more mild. The localised form tetanus that develops in dogs ma be difficult to diagnose, particularly if there is no history of trauma.  

==Signalment==

==Signalment==

===Clinical Signs===

===Clinical Signs===

The localised form of tetanus seen in dogs may cause differing clinical signs to those seen in other species. Unlike the generalised spastic paralysis seen in horses, dogs may present with an obvious wound and stiffness or rigidity in a single limb. The rigidity may spread to the contralateral limb and then begin to advance cranially. Dogs may often display hypersensitivity to even minimal amounts of stimulation. Affected cases have been reported to display caudal displacement of the ears, lateral canthi and commissures of the eyes. Dogs may also display prolapse of the nictating membranes.

The localised form of tetanus seen in dogs may cause differing clinical signs to those seen in other species. Unlike the generalised spastic paralysis described in horses, dogs may present with a wound to a single limb and unyielding stiffness or rigidity in the surrounding area. The rigidity may spread to the contralateral limb and then begin to advance cranially, and the disease usually becomes generalised at this stage. Dogs may often display hypersensitivity to even minimal amounts of stimulation. Affected cases have been reported to display caudal displacement of the ears, lateral canthi and commissures of the eyes. Prolapse of the nictating membranes, trismus (excess jaw tone) and retracted lips (risus sardonicus) are other reported clinical features.