CHAPTER III. 

 FUNCTIONAL NERVOUS DISEASES. 



VERTIGO. 



Definition. — ^Vertigo is a symptom and not a disease. It is 

 characterized by dizziness, a disorder of the equilibrating 

 sense, causing a feeling of instability and apparent rotary 

 movement of the body or other objects. Vertigo is very 

 possibly due to a disturbance in the equilibrating center in 

 the cerebellum. 



Occurrence. — Vertigo is not common in animals, but is 

 occasionally seen in horses and dogs. As a rule, the heavier 

 breeds of horses are affected. 



Etiology. — In animals vertigo is usually secondary to brain 

 diseases, such as acute and chronic encephalitis and epilepsy. 

 It may also attend chronic diseases of the lung and heart, 

 which cause venous congestion in the brain. Compression of 

 the jugulars from the collar of the harness is a common cause. 

 Vertigo is a symptom of anemia of the brain; it can also 

 come from eating poisonous plants. An ocular vertigo is 

 occasionally seen in horses due to light effects, such as result 

 from shiny blinders or bright light shining in the face or 

 occasionally from driving the horse through an alley of trees 

 which cast their shadows across the roadway. 



Symptoms. — ^The horse is usually attacked at work. The 

 patient begins throwing and shaking its head, running back- 

 ward a few steps, swaying in the shafts, and after staggering 

 about falls to the ground, where it lies unconscious and quietly 

 for from one to five minutes. After coming out of the attack 

 the animal regains its feet and seems to be normal again. 



Diagnosis. — ^The diagnosis of vertigo is usually readily 

 made, but to determine its cause is often extremely difficult. 

 It may be distinguished from epilepsy by the absence of 

 convulsions while the animal is down. 



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