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.
Fever results from the increased muscle activity.
The animal also becomes hypersensitive to external stimuli. An antibiotic and antitoxin should be given. The antibiotic should be effective against anaerobes. 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. Valium is commonly used as needed to control rigidity and help keep the body temperature down.