Tetanus is a highly fatal disease of all animal species caused by the neurotoxin of Clostridium tetani. The bacterial spores are deposited in tissue, usually by traumatic injury, retained placenta or endometrial injury and under anaerobic conditions vegetate. Clinical features of the disease are remarkably similar in all species but there are differences in susceptibility to the disease. The muscle spasms cause a stiff gait, rigid posture (sometimes called 'sawhorse stance'), extension or elevation of the tail, protrusion of the third eyelid and trismus (lockjaw). Horses show flaring of the nostrils. In dogs, spasms of facial muscles cause abnormally erect ears and retraction of the lips that resembles the 'risus sardonicus' seen in humans with tetanus. Stimulation precipitates generalized muscle contractions and tetanic spasms or convulsions. The disease can be prevented by immunization with tetanus toxoid or the use of antitoxin, but this is done routinely only in humans and…