TETANUS IN DOGS: CLINICAL SIGNS AND MANAGEMENT

1 . It is a potentially life-threatening condi- tion, but, with appropriate management and inten- sive supportive care, these cases have the potential for a good prognosis. This article will summa- rise the pathogenesis, typical clinical presentation and diag- nosis of this disease, before focusing on the manage- ment of tetanus in practice. Pathogenesis Tetanus occurs as a result of infection by the Gram-posi- tive anaerobic spore-form- ing bacterium Clostridium tetani. The bacillus is found ubiquitously in the environ- ment and entry into the body is most commonly via an infected external or surgical wound (with recent ovar- iohysterectomy being the most frequently reported procedure), or via the oral cavity in association with tooth root abscessation or loss of deciduous teeth in thetic dysregulation may be observed in the same patient, presenting as violent "auto- nomic storms" of bradycardia, tachycardia, hypotension or hypertension. Up to 30 per cent of humans with tetanus may show autonomic dys- function, with sympathetic overstimulation predominat- ing, and it has been associ- ated with a poorer progno- sis 2,3 . A previous case series of 38 dogs reported signs of autonomic dysfunction in 14 dogs, with bradycardias and bradyarrhythmias being most commonly observed 2 . ABSTRACT Tetanus is a potentially life-threatening disease in dogs seen following infection of a wound or surgical site by the spore-forming bacterium Clostridium tetani. Subsequent production of a potent neurotoxin results in local or generalised disinhibition of motor neurons and sustained muscle spasms. Clinical signs involving the face, such as an abnormal expression, erect ears and trismus, are often first observed, before progression to generalised stiffness and extensor rigidity of all limbs. There is no definitive diagnostic test readily available for tetanus and a diagnosis is often made on the basis of characteristic clinical signs. Management of tetanus is initially focused on identification and cleaning of any wounds, together with antibiotic administration. Metronidazole is the antibiotic of choice in both dogs and humans. Tetanus antitoxin may also be administered to neutralise circulating toxin, but its efficacy remains uncertain. Supportive care is then required until recovery can occur over four to six weeks. This may be intensive, particularly in severely affected cases, and focuses on care of a recumbent patient, nutritional support and the use of sedatives and muscle relaxants as required for managing the muscle spasms. Published survival rates for dogs with tetanus are variable, with estimates ranging from 50 per cent to 92 per cent. Severe complications, such as hyperthermia, cardiac arrhythmias and aspiration pneumonia, can be encountered and may be associated with a worse prognosis.