"The simple ulcer or the healing sore is very apt to become a weak ulcer as the result of defective blood-supply, either from too small a quantity of blood being sent to the part, as in cases where the vessels are diseased, or from deficient quality of blood, for example, during the progress of some constitutional disease. In this form of ulcer the granulations become smooth and somewhat yellowish, the secretion thin and small in amount, and very apt to scab, and the edges pale and flat. In other cases of weak ulcer the granulations become cedematous, and this is more especially the case where there is some general cause of oedema or some local interference with the circulation, such as compression of veins from the contraction of the sore, etc. Or again, we have another form of weak ulcer, where the granulations show excessive growth. This is chiefly the case where the ulceration is due to inability of the sore to contract. In such cases the granulations become prominent, vascular, soft, and bleed readily, and we have the condition which is popularly spoken of as 'proud flesh'.
"These simple ulcers again may become attacked with some septic virus which leads to what is called the phagedsenic ulcer. In the latter case the ulcer becomes covered with grayish pulpy material, which rapidly infiltrates the surrounding skin and cellular tissue, and extends both superficially and deeply at the bottom of the sore, leading to extensive and very rapid destruction of the part, and not uncommonly to the death of the patient." - Watson Cheyne.
In the treatment of ulcers, as in the treatment of wounds, it is desirable to remove all causes of irritation, and especially the septic discharge with which they are usually covered. In this connection the antiseptic method applied to wounds must be resorted to here. The hair must be removed from around the ulcer, and the skin cleansed and rendered aseptic. The ulcer must then be disinfected. This may be accomplished either by the application of a solution of chloride of zinc (40 grains to the ounce), or by touching the surface with nitrate of silver, or by scraping away the septic granulations and subsequently applying undiluted carbolic acid. Following this, the wound should be dressed every day with boracic-acid ointment, half strength, and covered with three or four layers of boracic-acid lint. In some cases of callous ulcer, gentle pressure will be found of service where bandages can be applied, or a mild blister to the edges of the wound may hasten the healing process. In long-standing cases, the actual cautery may be lightly applied to the surface of the sore with good result, followed by the application of boric-acid dressings.
Specific Infective Ulcers are the result of the action of pathogenic or disease-producing bacteria. The more common examples in the horse are seen in that form of glanders termed farcy. Recently a contagious form of lymphangitis has been introduced into this country from South Africa, in which specific ulceration of the skin is a leading feature of the affection.
Maladie du Coit, a venereal disease prevailing on the Continent and but seldom seen in this country, offers another example of this class of ulcer.
For particulars of these ailments, refer to them under their respective headings.