DISEASES OF THE NERVOUS SYSTEM. 315 



Pathology. — No absolutely characteristic post-niortem 

 appearances are known. Evidently the changes are func- 

 tional modifications of the brain-cells chiefly. 



Symptoms. — These are principally expressed in the 

 behavior and appearance of the dog. At first he may be 

 very quiet, shy, sullen, inclined to hide away in corners ; 

 but sooner or later he is likely to show more or less ex- 

 citement. The dog is profoundly altered in his psychic 

 nature, and this is most evident to those who are accus- 

 tomed to observe dogs, though in well-marked cases obvi- 

 ous to any one. He may seem more affectionate than 

 usual, or the reverse. If a bitch, she may be sexually 

 excitable, inclined to solicit attention from dogs of the 

 opposite sex. Much stress must be laid on perverted ap- 

 petite, the animal swallovring all sorts of foreign material 

 — as sticks, stones, straw, even its own fseces and urine. 

 The voice is altered to a short bark, often ending in a sort 

 of howl or moan which is characteristic. 



At this early stage the animal may or may not snap at 

 objects or champ the jaws. 



During the excitable stage, which may be well-marked 

 or the reverse, the dog is prone to roam over wide tracts 

 of country at a jog-trot, head down, tongue out, but not 

 usually frothing at the mouth, with a dejected look and in- 

 different to what is about him, yet snapping at any animals 

 that happen to come in his way. He may return to his 

 home if not interfered with. The biting and snapping 

 should not be regarded as deliberate, but as a sort of reflex 

 action, or at all events as more or less unconscious. It is 

 then the dog is most dangerous to other animals. A sort 

 of bluish tinge to the mucous membrane of the mouth may 



