194 SYNOPSIS OF VETERINARY 



tain limits by the mydriatics, its sudorific action is increased by 

 ipecacuanha. 



Physiological Actions. — Opium is analgesic, hypnotic, dia- 

 phoretic, antispasmodic, narcotic ; also cardiac and respiratory 

 depressant, after primary brief stimulation. 



In Medium Doses. — It dries all the secretions, except those 

 . of the mammse and skin. The latter being increased, it produces 

 dryness of the mouth and throat, arrests gastric secretions, re- 

 tards digestion, and causes anorexia (loss of appetite) ; it stimu- 

 lates the brain by increasing the blood supply ; in man it stimu- 

 lates the mental activity, while in animals it stimulates motor 

 activity ; it does not affect the conductivity of nerves, but it pre- 

 vents the consciousness of pain by paralyzing the nerve centers ; 

 the action of the heart is increased and arterial tension is raised, 

 the pupil slightly contracted ; the mind at first stimulated, becomes 

 calm, sleep follows, disturbed by dreams and headache; constipa- 

 tion and some depression result. 



In Full Doses. — It arrests digestion, causes nausea and vom- 

 iting (in animals capable of emesis), greatly increases the sweat, 

 prevents the conductivity of nerves, depresses the heart and cir- 

 culation, impairing oxidation and lowering temperature, it con- 

 tracts the pupil by stimulating the motor oculi (in horses it di- 

 lates the pupil) and causes intense pruritus (itching), especially 

 of the nose, often retention of the urine, and soon profound sleep ; 

 in some cases coma or delirium, leaving as after effects, nausea, 

 depression, constipation, vertigo, anorexia, nasal pruritus, and 

 fetid pathological secretions. 



A Toxic Dose. — Produces cold clammy sweat, very slow 

 heart, diminished quantity of urine, abolished reflexes, coma, 

 the pupil minutely contracted, (except in the horse) spoken of as 

 pin point pupil by physicians, but dilated as the end approaches 

 and death by suspension of respiration due to direct action of 

 the poison on the respiratory centers in the medulla. 



Post-Mortem. — Shows no characteristic lesions, find wet 

 brain, congested lungs, and engorgement of the venous trunks 

 and right side of heart. 



Morphine and" Codeine as compared with the action of opium; 

 Morphine is more anodyne and hypnotic ; it causes more intense 



