This is a product of the distillation of coal-tar, and is chemically known under the several names of phenic acid, phenol, and phenylic alcohol. The colourless, needle-shaped crystals of pure carbolic acid are not convenient for surgical purposes unless broken down with glycerine or some other solvent. A comparatively impure acid is equally efficacious, and in general use more economical and convenient. The preparations of value to the veterinarian are glycerine of carbolic acid, carbolic lotion, carbolic ointment, and carbolic oil.
Carbolic acid is both a disinfectant and an antiseptic, and though only mixable with or soluble in water to a small extent, it can be made more so by the addition of glycerine, and is then employed in different proportions for a great variety of purposes. Strong solutions destroy living organisms, while dilute preparations merely prevent their growth. Besides being an antiseptic, carbolic acid is also a caustic when applied undiluted to the skin, leaving a white mark as evidence of the superficial layers being destroyed. Acute pain is felt at the moment of application, but the sensibility of the integument is subsequently diminished.
It is a valuable agent in the treatment of ulcers, cracked heels, and such diseases. Ringworm and other affections having their origin in low forms of life are successfully combated with strong carbolic applications, which are mostly made in the form of an ointment. Some forms of skin irritation arc allayed by weak lotions of carbolic acid, while the mange mite and other external parasites are either immediately killed by it or caused to quit the body of their host.
Applied internally, it is a safe and useful agent in the treatment of those ulcerative conditions which affect mucous membranes, more especially those of the nostrils, mouth, throat, and other parts accessible to the surgeon.
The foetor of the breath arising from dental troubles, and referred to at some length, is subdued by a suitable mouth-wash in which carbolic acid is the active ingredient.
It is occasionally employed as an inhalation in certain forms of catarrh in which malignant sore-throat is a prominent symptom.
Carbolic acid is prescribed internally in some instances where the production of gases from fermented ingesta is a direct cause of flatulent colic and other intestinal troubles.
Sulpho-carbolate of soda, as an internal remedy, is particularly adapted to those fermentative conditions of the stomach and bowels referred to in the last paragraph. It appears to have all the antiseptic advantages of carbolic acid without its irritative effects. The sulpho-carbolate of zinc is chiefly used as a dressing for wounds. In addition to its antiseptic properties it has a beneficial action in the repression of too profuse granulations or " proud flesh ".
Resorcin, another product of fractional distillation of coal-tar, is in its action very similar to carbolic acid, but possessed of other properties not yet fully understood.
It has been used by veterinary surgeons only for a short time, but is highly spoken of by them in the treatment of wounds, and for the prevention of fermentation in the stomachs of animals which have gorged © © themselves with food.
Creasote is another, and one of the oldest, of coal-tar distillations used in medicine. Inhaled, it is quite as effectual as carbolic acid, and much safer.
As an ointment, it is destructive of parasitic life without unduly irritating the skin of the patient, and as an antiseptic dressing it is also a useful agent.