426 Nervous Disturbances. 



conditions indicated disturbances of the blood circulation arise, 

 as compresison of the large veins before opening into the rigid 

 walled sinuses, with resultant stasis, interference with the escape 

 of venous blood and cerebro-spinal fluid, and the production of 

 increased pressure upon the brain substance ; that, further, in 

 the conditions mentioned increased formation of this fluid and 

 special tissue changes in the brain may obtain, and perhaps, too, 

 toxic influences (bacterial toxines^ autotoxines). 



Psychical excitement has its causative factors in hypersemia 

 of the brain, cerebral inflammatory changes, heat or toxic influ- 

 ences, and occurs in a number of difl^erent degrees of severity. 

 The main symptoms are manifested as attacks of insanity 

 {mania, delirium fnribundum). The animals in these attacks 

 suddenl}^ lose their docility, try to free themselves from their 

 fastenings, bite their owm bodies, make attacks in whatever way 

 is natural to them (strike out, kick, try to bite), run into obstacles 

 and violently knock them over, stand up on their hind legs and 

 throw themselves about with shrill cries, grit their teeth and 

 froth at the mouth ; the eyes become staring and wild, the con- 

 junctivae injected; and finally the animals collapse and go into 

 spasms and convulsions. Especially in dogs of usually aitec- 

 tionate and lively disposition, well-trained and possessed of 

 special intelligence we meet with the widest range of mental 

 disturbances, from melancholia to hallucinations (fancied per- 

 ceptions), marked confusion and insane outbursts, as in rabies 

 (depressed stupid condition, snapping at the air, purposeless 

 wandering about, sudden attacks of desire to bite, tearing of the 

 animal's own flesh), or in poisoning with deadly night-shade or in 

 sunstroke. Similar symptoms of excitement are seen in dogs 

 in the autointoxication produced by the portal blood, that is, the 

 absorbed products of albuminous decomposition in the intes- 

 tine, in Eck's fistula [fistula made between the portal vein and 

 vena cava with diversion of the portal blood from the liver]. 

 Special nervous excitement and reflex psychic conditions occur 

 in some of the diseases of the genital organs (ovarian cysts, 

 ovarian tuberculosis, uterine affections, undescended testicle), 

 the ' affected animals manifesting (uterine, ovarian, orchitic 

 psychoses) an exaggerated sexual desire (nymphomania, satyriasis, 

 erotomania, rutting, sexual insanity). 



There are, too, a number of vague nervous conditions which 

 l^ad to perversions of taste (perversions of appetite) manifested 



