The lips may become diseased from a variety of causes. In some instances the disease may be of constitutional origin, in others of a purely local character. Besides common ailments, these organs are also now and again the seat of specific eruptions arising in the course of contagious diseases. In addition to abrasions and other injuries, they are liable to suffer by exposure to such substances as lime or blistering material, used on the limbs and other parts without adequate precaution having been taken to prevent the animal from rubbing them with his muzzle. Vesicles or blisters and erosions may in this way be produced on the outer skin, making contact with dry food painful and chewing difficult.
Vesicles produced in this way generally run into one another, causing the skin to crack and ulcerate and the tissues of the lips to become swollen, and in this condition their mobility is more or less impaired and food is gathered with difficulty.
Old wooden mangers, splintered by animals affected with the vice of crib-biting, are sometimes responsible for sore lips, which are also induced by improper removal of warts and by indiscriminate use of caustics so much in favour with old-world farriers. On the muzzle and lips of colts at pasture warts will sometimes form in countless numbers, and their proper treatment will come under consideration when speaking of diseases of the skin generally.
The angles of the mouth are also sometimes observed to be cracked, ulcerated, and inflamed, as a result of the use of sharp bits and the cruel and foolish practice adopted by breakers of the more ignorant class of placing blistering material upon them with a view to obviating "hard mouths ". No method more calculated to defeat its object could be devised, as the ultimate result is thickening of a permanent nature and reduction of the sensibility of the parts. Oil of vitriol and sugar smeared upon the bit, with the object of producing a glossy coat, is another device of ignorant carters, resulting in sore lips.
The mucous membrane covering the inner side of the lips is liable to become injured from without by blows forcing it against the teeth, or from extension of inflammation from the corners of the mouth.
In certain forms of inflammation of the mouth, as well as in horse-pox, these organs are the seat of eruptions which may occur on one side or the other or both.
In this connection no great difficulty need be anticipated. Of the troubles we have been speaking, most can be successfully combated by remedies with which the patient himself will assist us. We refer, of course, to the use of warm, sloppy food, as bran mashes, boiled meal, pulped roots, scalded bread, and like emollients, which must necessarily be brought into contact with the parts affected and produce a good effect before the patient can swallow them. To guard against irritation of the injured surface, hay, corn, and chaff should be scalded and rendered soft and easy of mastication. Nature alone will sometimes effect repair with these simple precautions and the rest which they afford to the inflamed parts. Medicaments of the simplest kind should be chosen if any are needed. In alum solution we have almost a specific for sore places of this kind, though more active agents may be requisite where ulceration and indolent wounds require to be treated. It may be necessary to stimulate a pale, languid sore by touching it with a solution of nitrate of silver, or sulphate of copper (blue stone), or some other agent of a similar character, to induce the healing process.
A liberal dressing of vaseline or lard, to soften the skin, will afford the patient comfort, and should not be omitted in dealing with a delicate horse which is easily deterred from feeding. The old-fashioned remedy known as Friar's-Balsam has an excellent healing effect, and is a most suitable application to lip wounds. It should he applied by means of a camel-hair brush morning and evening.