Diagnosis. 603 



out any sensory disturbance. Pronounced improvement may 

 be observed in protracted cases. The animal may improve to 

 such an extent that it may return to work, but after a time the 

 disease may reappear and possibly in a more severe form, death 

 occurring shortly after. Such relapses may be due to great 

 heat or to some external stimulus. 



Complications are of frequent occurrence, the most common 

 of which are h3^postatic pneumonia or pneumonia due to foreign 

 bodies, septicemia or pyemia. 



Diagnosis. In well-marked cases diagnosis is not, as a rule, 

 attended with any difficulty, especially if the history of the case 

 affords any information as to the nature and the manner of the 

 infection. In this connection the following points are of im- 

 portance : suddenly occurring disturbances of consciousness, 

 squinting due to disease of the nerves controlling the muscles 

 of the eyes, contraction or unequal dilatation of the pupils, 

 spasms of the muscles of the neck, trismus, active congestion of 

 the papilla of the optic nerve, paralysis of the cranial nerves 

 which is present in some cases, vomition in the dog and pig, and 

 painfulness of the top of the cranium. If the disease is not 

 fully developed and only symptoms of a general nature are to 

 be observed diagnosis presents considerable difficulty and may 

 be impossible. 



Dullness and stupor are observed in a number of infectious 

 diseases, but in these cases the symptoms of brain disturbance 

 are not pronounced and there is an absence of impulsive move- 

 ments. In malignant catarrh the disease of the eyes (opacity 

 of the cornea and fibrinous iritis) and the nose supplies a satis- 

 factory explanation of the direct cause of the dullness. The 

 differential diagnosis of rabies, suspicion of which may be 

 roused by the attacks of mania, is based principally upon the 

 absence of muscular spasms and the fact that rabies terminates 

 fatally in eight or nine days at the most. Simple acute cerebral 

 hyperemia may sometimes cause symptoms of excitement and 

 dullness to a slight extent. Differential diagnosis in this in- 

 stance is based upon the rapid and f avoral)le course run by the 

 disease. In the absence of a complete series of characteristic 

 symptoms it is scarcely possible to distinguish between simple, 

 acute meningitis and purulent meningitis. In the case of the 

 horse acute relapses of chronic dropsy of the ventricles have 

 to be taken into consideration. The primary meningitis occur- 

 ring in cows at calving differs from parturient paralysis in 

 that there is fever, the pupils are contracted and in some 

 cases there are general convulsions. 



Certain poisons (lead, santonin and bacterial toxins) some- 

 times cause meningitis which is so similar in its characters that 

 a diagnosis can be made only by a postmortem examination. 

 In the dog pentastomatosis and helminthiasis must be taken 

 into consideration, and in the ox and sheep staggers. Deep- 



