DISEASES FROM SEPTIC INFECTION OF WOUNDS 369 



use is boric-creolin (1 part of ci-eolin to 40 or 50 parts of boric acid), 

 naphthalin or sulphonal (1 part to 5 parts of starch), dermatol, airol, 

 aristol, bismuth subnitrate or zinc oxide. An open wound generally 

 recpires antiseptic washings daily. It frequently happens that granu- 

 lating wounds, especially when they have been subjected to exposure to 

 air or are constantly irritated by the animal, may at some period lose 

 their power of healing and become converted into ulcers. 



Ulcers or Ulcerations. — By this we understand a granulating surface 

 which does not heal on account of the purulent destruction of the granular 

 tissue. Wounds are changed into ulcers when they are continually 

 irritated by some mechanical or chemical irritant, or as a consecjuence of 

 the skin becoming inflamed or necrosed from pressure (muzzling, etc.). 

 Callous ulcers and fistulous ulcers are the most difficult to treat. The 

 former are superficial ulcers with hard, callous centre, having raised 

 edges, and a whitish, hard, bacon-like surface. This is covered with a 

 thin unhealthy secretion. They may form sinuses or canals, which very 

 often contain, at the bottom of the sinus, a foreign body or necrosed 

 tissue. They may also lead to some of the glands. These pipes are 

 called fistulse or fistular canals. 



The treatment of ulcers is, to a certain extent, the same as that of 

 wounds — that is, to follow all the antiseptic rules. The use of dermatol, 

 airol, aristol, subnitrate of bismuth, salicylic acid, naphthalin, powdered 

 camphor, or boric-acid ointment is advisable. We may also remove 

 callous ulcers by surgical means and convert them into fresh wounds by 

 taking a knife, paring the tissue at the bottom of the ulcers, and treat 

 them as indicated in cases of fresh wounds. Caustic agents produce 

 little or no good effects. If the tissue surrounding the ulcers is hard and 

 rigid, preventing contraction of the ulcerated area and the healing 

 process, we must perform circumcision of the part, as transplantation 

 is not practicable in the dog. We cut about 1 cm. from the border of the 

 ulcer over its entire thickness, keeping the wound open by means of 

 vaselin. When we treat a fistulous canal and the location of the fistulous 

 sinus admits of it, we split open the fistulous passage and convert it into 

 an open wound. When the fistulous canal is not very deep we may also 

 try to produce healthy granulations by means of actual cautery, or the 

 injection of caustic fluids or the introduction of crayons of caustic 

 (nitrate of silver or caustic potash). Always try to slit open the canal, 

 if possible, as it produces the best effects. Nitrate of silver or any of 

 the mineral acids, and in obstinate cases a small piece of corrosive sub- 

 limate, is pushed down into the bottom of the wound; these caustics 

 produce more or less irritation and consequent sloughing of the wall of 

 the canal and allow the growth of healthy granulations. 



Contusions. — In subcutaneous wounds of the soft tissues (bruises 

 24 



