DERMATITIS.
Under this head may be included a class of inflammations of the skin, due mainly or entirely to external causes, not essentially parasitic, and attended by distinct eruptions (papular, vesicular, pustular, etc.). Many of these are but an advance beyond the simple erythematous inflammation, and coincide with it, the one condition being present at one part of the diseased area, and the more advanced and severe lesions at another part. Bearing in mind the frequency of this connection, it will be unnecessary to dwell at length on this class of affections.
Dermatitis Traumatica. Dermatitis from Mechanical Injury. Besides the veritant factors already named as causing traumatic erythema, we must here recognize contusions, over-reaching, treads, interfering, bruising and chafing by harness, girths, circingles, hobbles, ropes, traces, twists, and blows with whip, club, chain or rope. Here the source of injury must be removed, by attention to shoeing, harness, etc., and the lesions treated according to their gravity as simple wounds.
Dermatitis Venenata: Dermatitis Calorica. These, like the corresponding erythema, come from contact with irritant plants or animals or their products, from excessive heat or cold, and may show any grade of eruption or even gangrene and sloughing. Apart from the washing off of the irritant or venomous matter and the application of alkalies or permanganates in the case of the latter, these must be treated like ordinary sores. In burns, especial value attaches to solutions of sodium bicarbonate, and preparations that will exclude the air. Vesicles may be emptied by puncture and the part covered with cotton soaked in carbolated sweet oil and lime water, or carron oil (linseed oil and lime water) may be freely applied, or a resorcin solution (2:100 water), or a thick varnish of linseed oil and litharge, equal parts, with 5 per cent. of salicylic acid, melted and painted over the surface. A layer of surgeon’s cotton covered by a rubber bandage where admissible, will complete the dressing. In the process of healing, skin grafting may be required. Thin slices of cuticle are placed in the center of the granulating surface, or at intervals and carefully bound in place.
When a part has been frozen the usual method is to recover circulation slowly by rubbing with cold water or snow. The parts are then treated by astringent and antiseptic dressings. If the skin sloughs use antiseptics until it separates, and then treat like an ordinary sore.
Chillblains may be treated with a mixture of sweet oil, 5 ozs., oil of turpentine ½ oz., Aqua Ammonia ½ oz., oil of peppermint 1 dr., or powdered camphor 10 grs., Peru balsam 20 drops, linseed oil 2 ozs. Nourishing food and a course of iron should be given.
Dermatitis Medicamentosa. Medicines given by the mouth sometimes cause inveterate skin eruptions. Among these are arsenic, belladonna, bromides, iodides, mercurials, salicylates, tansy, turpentine, tar, and the carminative seeds and oils. The latter are chargeable with many eruptions in live stock fed on patent foods. In cattle treated with iodides for actinomycosis, an universal eruption and desquamation is a common condition. In all such cases the drug must be withheld, the bowels cleared out by a purgative and the elimination of any remaining irritant products favored by gentle diuretics.