MENTAL DIFFERENCE AND DISORDER. 213 



marked group of morbid mental symptoms, and this group 

 is so important in the case of rabies that the subject of the 

 insanity of rabies in the dog, for its proper treatment, would 

 require at least a chapter for itself. I have already specially 

 treated of it elsewhere. The group of mental symptoms 

 which accompanies rabies is usually considered distinctive 

 and diagnostic. But this can scarcely be correct ; because 

 the disease itself is constantly being even by veterinarians 

 mistaken for, or confounded with 



a. Various forms of insanity especially mania. 



fc. Mere transient fury, passion, or despair. 



c. The results of peripheral irritation such as the pre- 

 sence of intestinal worms or mechanical impaction the 

 results, in other words, of the presence of foreign bodies in 

 various organs. 



Various poisons animal, vegetable, or mineral produce 

 in the lower animals conjoint physical and mental symptoms 

 sometimes of the same kind as in man ; sometimes diverse 

 the difference in their action or its results, where such dif- 

 ference exists, being generally, if not always, due to the very 

 different structure and habits of the animal affected. 



Just as in man, again, all organic disease of the brain 

 congenital or traumatic, want or loss of its substance, 

 defective, arrested, or perverted brain-growth are apt to be 

 attended with, or to lead to, mental defect or disorder. 

 Functional disorders of the brain or general nervous system 

 are also accompanied by or produce the same kind of mental 

 disturbance as in man. Thus epilepsy, which is not uncom- 

 mon in the dog and other animals, is apt to beget, or to be 

 associated with, the same forms of mental degeneration as 

 in man. It has been noted as a frequent precursor of mania, 

 dementia, and death in certain animals. Apoplexy is another 

 brain disease attended with mental impairment. Brain 

 hydatids, which cause the c sturdy ' of sheep and cattle, give 

 rise to a special group of mental symptoms. Pierquin men- 

 tions brain hydatids and cerebral ramollissement as causes 

 or concomitants of idiocy in animals. Mental symptoms 

 similar to those of sturdy are produced by inflammations of 

 the brain or its meninges (Delacour), by metastasis of erysi- 



