Answers and Discussion

Answers and Discussions to the Questions:

• How is the diagnosis of tetanus made?
  
  Diagnosis is based on clinical signs and history of a previous wound.   Typical signs include generalized muscle spasms which usually begin on the head.   This results in the characteristic dorsal retraction of the ears, retraction of the lips, elevation of the upper eyelids, and prolapse of the third eyelids.  These muscle spasms can progress to dysphagia, difficulty opening the mouth ("lockjaw"), and difficulty breathing.  Fever results from the increased muscle activity.  The animal also becomes hypersensitive to external stimuli.

• Which two drugs should be given to treat the tetanus infection?
  
  An antibiotic and antitoxin should be given.  The antibiotic should be effective against anaerobes.  Penicillin G (20,000-100,000 IU/kg QID, IV or IM) is commonly used.  Before giving equine tetanus antitoxin, test for an anaphylactic reaction by injecting 0.1-0.2 ml SQ and watching the area for 30 minutes.  Then administer 100-500 IU/kg IV, usually only once.

• How would you treat the hypertonia to achieve muscle relaxation?

  Valium is commonly used as needed to control rigidity and help keep the body temperature down.   Typically 5-10 mg is given IV every 2 to 4 hours in the dog.  Barbiturates may also be used.

• What other types of supportive care are important?
  
  A dark, quiet environment with minimal handling is useful when dealing with a hyperesthetic patient.  The dog may also be sedated with acepromazine.  Fluid therapy should be instituted.  Typically, Normosol with added potassium chloride maintains the animal well.  Most dogs have a problem eating so they should be fed small frequent meals.  If they are recumbent, keep the cage padded and the dog clean to prevent decubital ulcers and urine scald.

• What is the prognosis for tetanus?
  
  The prognosis is more favorable when the condition is localized.  However, with generalized signs, the prognosis is guarded.  Animals that recover may show signs for 30 days or more before the muscle rigidity completely resolves.

• Follow-Up: "Fairlane" seemed stable when she left critical care in a few days to be monitored in the wards.  However, two days later in the early morning hours, she was found obtunded and dehydrated with a temperature of 106 degrees.  A thoracic radiograph was taken, which revealed a soft tissue density in the caudal dorsal thorax at approximately the level of the mediastinum.  While awaiting further diagnostics, "Fairlane" arrested and died.  A necropsy showed a possible gastroesophageal intussusception.  There was a hemorrhagic area in the cardia of the stomach and gastric edema.  The ovarian stumps were hemorrhagic and endocardial hemorrhage was present.

Tetanus Pearls

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Copyright 1999, Wayne E. Wingfield, DVM and Brenda McClelland, DVM, Colorado State University   
This page was last edited:  12/14/99