242 THEORY AND PRACTICE 



with occasional epileptic fits until the disease terminates in coma, 

 then convulsions and death. 



Pathology. — In autopsy, on opening the cranial cavity we no- 

 tice that the brain is altered in form ; the fissure between the 

 hemispheres is almost obliterated. In cutting down through the 

 corpus callosum you find water in the ventricles, varying in 

 quantity from 1 to 8 ounces. Upon emptying the water out we 

 find the septum lucidum broken down, making one cavity. The 

 arachnoid is thickened and opaque, particularly over the cere- 

 bellum and it is often studded with spots of inflammation. The 

 fluid in the ventricles is usually pale, thin and watery, but some- 

 times quite turbid. Effusion may take place into the lateral ven- 

 tricles, or into the subarachnoid space. A horse so affected in 

 the chronic form is a dummy. 



The treatment is not very satisfactory. In mild cases the 

 disease may give way to iodide of potash, iron, vegetable bitters, 

 and mild counter-irritants externally. Keep the animal quiet; 

 give soft diet and rest. 



TABES DORSALIS. 



Tabes dorsalis or locomotor ataxia, is the same as sclerosis 

 of the cord. It is sometimes called "crick back." In the do- 

 mestic animals the disease affects the white matter of the cord. 

 In the human the gray matter may also become involved. This 

 condition is a contraction and hardening of the columns of the 

 cord. In the horse it is usually the supralateral columns. The 

 inferolateral may also become affected. The loins are about the 

 first to become affected, but the disease may start in the cere- 

 bellum and travel down the cord. The motor columns are 

 affected more than the sensory. 



Etiology. — ^The disease usually develops as the result of ex- 

 posure to cold and storms, especially if the horse is not in 

 good condition. It may occur in old horses and debilitated 

 ones. The minute vessels of the cord are diminished in size and 

 the gray matter can be easily ruptured. In cases of syphilis in 

 horses this condition is always present. 



Semeiology. — Tabes dorsalis comes on slowly. We notice 



