PRINCIPLES OF VETERINARY SURGERY 479 



sions may exist without any etiological analogy. Strychnized 

 rabbits killed three minutes after injection exhibit lesions of 

 the motor cells as in tetanus 



These lesions are neither characteristic of tetanus nor 

 productive of it. 



Blumenthal expresses the opinion that the lesions ob- 

 served on animals suffering from tetanus are neither specific 

 nor constant. Tetanus must be considered as a consequence 

 of anatomical alterations of the nerve cells. 



Nageotte and Ettlinger studied the medullas of cavies 

 without finding the lesions described by Marinesco. They 

 found chromatolysis, vacuoles and fissures. The lesions 

 occupied the entire medulla and therefore have not the topo- 

 graphy that corresponds to the contractions. They may 

 exist in cavies not tetanized, for example in poisoning from 

 potassium iodide. A\'riters consequently deny that there is 

 any connection between the lesions obser\'ed in animals af- 

 fected with tetanus and the contractions which characterize 

 the intoxication. In recent works Courmont, Doyon and 

 Paviot have shown that the medullary lesions seen in the 

 cavy may exist without tetanus and that tetanus may exist 

 without them. They are not pathognomonic. From all of 

 these investigations the conclusion must be drawn that the 

 actual nerve lesions of tetanus are not known. 



DIAGNOSIS. — The diagnosis of complete tetanus is ex- 

 tremely easy. The symptoms are typical. There are few 

 diseases so well characterized. General rigidity, difficulty of 

 movement, trismus, displacement of the membrana nicti- 

 tans and the position of the head, ears and tail are pathog- 

 nomonic symptoms in the horse. In the beginning, when 

 the tetanus is incomplete and local, indecision is permissible, 

 but this phase of the disease is of short duration. It rapidly 

 becomes general. Tetanus is easily differentiated in the 

 horse, from laminitis, rabies and cerebro-spinal meningitis, 



