Sometimes, wounds are given special names, as gun-shot, poisoned, and open joint, depending on the nature of the cause and region involved.
Bleeding or hemorrhage is the most constant symptom. The degree of hemorrhage depends on the kind, number and size of the blood-vessels severed. In arterial hemorrhage, the blood is bright red and spurts from the mouth of the cut vessel. In venous hemorrhage, the blood is darker and flows in a continuous stream. In abrasions and superficial wounds capillary hemorrhage occurs. Death may follow severe hemorrhage. Weak pulse, general weakness, vertigo, loss of consciousness and death may result if one-third of the total quantity of blood is lost. Unthriftiness and general debility may follow the loss of a less quantity of blood.
The following symptoms may be noted in the different kinds of wounds: The sensitiveness to the pain resulting from accidental or operative wounds varies in the different individuals and species, and in the kind of tissue injured. Injuries to the foot, periosteum, skin and mucous membrane are more painful than are injuries to cartilages and tendons. The appearance of the wound varies in the different regions and the different tissues.
If the tissues are badly torn or bruised, swelling and sloughing may occur. If the wound is transverse to the muscular fibres, it gaps more than when parallel to the muscle. When infected by irritating organisms, open and punctured wounds (Fig. 58) become badly swollen, discharge pus freely and heal slowly with excessive granulations. Wounds involving tendons, bursae and closed articulations become swollen and discharge synovia. Wounds involving muscles, tendons and bursae usually cause lameness, and when involving a special organ, interfere with, or destroy, its function. Extensive or serious wounds may be followed by loss of appetite. An abnormal body temperature and other symptoms characteristic of the different forms of blood poisoning may follow infection of the injured tissues by certain germs.
[Illustration: FIG. 58.—A large hock caused by a punctured wound of the joint.]
The rapidity with which wounds heal depends upon the kind of tissue injured and the amount to be replaced, the degree of motion in the part, the kind and degree of infection and irritation and the general condition of the animal. In general, skin and muscles heal rapidly, tendons slowly, cartilages unsatisfactorily and nerve tissue very slowly. Healing is greatly interfered with by movement of the part (Fig. 59). The more nearly the part can be fixed or rested, the more quickly and satisfactorily does healing occur. Irritation by biting, nibbling, licking, bandaging, wrong methods of treatment and filth retard healing and may result in serious wound complications. An animal in poor physical condition, or one kept under unfavorable conditions for healing, cannot recover from the injury rapidly or satisfactorily.
[Illustration: FIG. 59.—A large inflammatory growth following an injury to the front of the hock.]
WOUND HEALING.—The following forms of healing commonly occur in wounds:
First and second intention; under a scab, and by abnormal granulation.
Healing by first intention occurs when the wound is clean cut and there is very little destruction of tissue, and when there is no suppuration or pus formation. The blood and wound secretions cause the edges of the wound to adhere. After a few days or a week the union becomes firm. Very little scar tissue is necessary in this form of healing.
Healing by second intention is characterized by pus formation and granulation tissue. After the first day, the surface of the wound may be more or less covered by red, granular-like tissue. Later this granular appearance is modified by an accumulation of creamy pus and swelling of the part, and finally scab formation and contraction of the new scar tissue.