TETANUS— LOCKJAW 417 



dilated, the nostrils distended and the nasal wings trumpeted. 

 The mouth is held shut with the commissures drawn up- 

 wardly. From a spasmodic contraction of the masseter 

 muscles it may be impossible to open the mouth more than a 

 fraction of an inch (trismus). Due to a contraction of the 

 constrictors of the pharynx, dysphagia and ptyalism are 

 present. While in most cases the back is held straight and 

 rigid, occasionally it is arched downwardly (opisthotonos) or 

 still more rarely curved laterally (pleurothotonos). Locomo- 

 tion is difficult, the limbs being advanced stiffly and the feet 

 barely raised from the ground. It is almost impossible to 

 back the horse. The muscles are tense and hard, individual 

 muscles standing out prominently. Twitching of the muscles 

 is a symptom often noted. These symptoms may subside 

 temporarily provided the patient is in no way excited. How- 

 ever, any sudden noise, a flash of bright light or an unaccus- 

 tomed sight will cause the spasms to return. If the patient 

 is struck with the hand a paroxysm of muscular contraction 

 passes over the body. The mind of the patient is clear 

 although the face shows anxiety and a peculiar rigid stare. 

 Sometimes in stallions the penis is erected. The pulse is 

 small, the artery hard. In severe cases the heart beat is 

 rapid and often palpitating. The respirations are increased 

 three to five times their normal frequency. As the blood is 

 charged with CO2 a cyanosis of the mucous membranes 

 appears. The lungs are commonly congested and edematous 

 so that rales are heard on auscultation. In rare instances 

 the respirations are noisy or pronounced roaring occurs. As 

 swallowing is difficult, saliva, food or drugs may enter the 

 windpipe causing foreign-body pneumonia and gangrene of 

 the lungs. The temperature is affected only in severe cases 

 and usually just before death or if some complication has set 

 in (pneumonia, septicemia). One to two days before death 

 it may reach 110° F. As has been observed in other diseases 

 accompanied by severe muscular spasms, the temperature 

 remains high for several hours after death (postmortal tem- 

 perature). The appetite usually remains good, although 

 mastication is labored. Food is often retained in the mouth or 

 coughed out into the manger. From a decomposition of the 

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