672 CANTHARIDES 



sometimes appear on the skin, depending on the excretion 

 of cantharidin cutaneously. 



EXTERNAL APPLICATIONS. Cantharides, in small amount 

 and diluted, stimulates the capillaries and trophic nerves of 

 the part to which it is applied, and thus increases the blood 

 supply and functional activity of the skin and hair bulbs. 

 It hence induces a healthier condition of the dermis in 

 some chronic scaly diseases, and promotes growth of hair ; 

 ulcers and tardily-healing wounds are stimulated, and their 

 repair encouraged. Inflammatory products are liquefied and 

 absorbed an effect familiarly illustrated by the action of a 

 blister on the swelling remaining around a bruise, or on the 

 fulness and thickening resulting from a strain. The bene- 

 ficial effects of a cantharides blister in arresting inflam- 

 mation and removing effusion were often exhibited when 

 blood-letting was the rule, and phlebitis of the jugular vein 

 of the horse was not infrequent. Blistering ointment, well 

 rubbed in along the course of the vessel, removed the tense, 

 corded, inflammatory swelling. 



Cantharides blister is usefully applied in cases of open 

 joint or bursa, where the wound is small, to prevent escape 

 of synovia. It is also applied in umbilical hernia in foals 

 and calves ; and while the consecutive swelling mechanically 

 prevents the descent of the intestine, the opening in the 

 abdominal wall is gradually obliterated. Similar effects 

 are sometimes obtained by moistening the adjacent skin 

 with sulphuric acid. 



Cantharides is much used as a counter-irritant. The 

 external irritation reflexly relieves tension, inflammation, 

 and pain of adjacent or deep-seated parts. Blisters applied 

 experimentally to the chest or loins of dogs and rabbits, 

 while producing external congestion, cause anaemia of the 

 pleura and lungs, or of the deeper-seated muscles of the 

 back. In pleuritic and other cases a blister notably modifies 

 morbid action, and relieves painful tension ; the temperature 

 is reduced 2 to 3 Fahr., and the pulse ten beats per minute. 

 Some prefer cantharides to mustard, believing it to cause 

 less irritation and pain, and to produce more permanent 

 curative effects. Others, however, maintain that can- 

 tharides and other blisters unnecessarily irritate most 



