VPT 421: Veterinary Toxicology (2+0)

Clinical Symptoms

CLINICAL SIGNS

• Tetany, the predominant clinical sign of tetanus, is characterized by sustained tonic contractions of muscle without twitching.
• Signs include hyperesthesia, tetany and convulsions with eventual rigidity of the muscles of respiration, asphyxia, and death.
• Clinical signs may include a sawhorse stance, protrusion of the third eyelid, rigidity of the generalized musculature, ‘sardonic grin’ and secondary postural effects which diminish defecation and urination.
• Rigidity with extension of the tail has been described for cats ‘pump-handle tail’.

• Opisthotonus and persistent rigid extension of all four limbs.
• Stiff gait.
• Horses, spasms of the masseter muscles occur early in the disease, ‘lock jaw’ results.
• If paralysis of laryngeal and pharyngeal musculature occurs, aspiration pneumonia may develop.
• Excitation or loud noises may elicit convulsions in hyperesthetic animals.
• Excess stimulation of sympathetic nervous system can occur with sweating, tachycardia, arrhythmias, vasoconstriction, colic.
• Complications due to recumbency occur.
• As the dose of toxin is increased, paralysis can result.
• Localized tetanus involving only the muscle groups closest to the site of injury is relatively uncommon.
• Characteristic ‘saw horse’ stance of a dog with generalized tetanus showing stiff, outstretched tail and contracted facial musculature.