Nematodes

Wounds

A wound is a break in the continuity of soft tissues caused by trauma. Wounds may be broadly classified into two categories, viz., Closed wounds and Open wounds.

Closed Wounds

A closed wound is a wound in which there is no break in the continuity of skin (or mucous membrane), but the underlying tissues are damaged to a varying degree, e.g., contusion, bruise, haematoma.

1. Contusion. A contusion is produced by blunt objects and results in damage to subcutaneous tissues without breaking the continuity of the skin surface. Contusions are classified into first, second and third degrees according to the extent or severity of the injury.

2. Bruise. A bruise is a mild degree contusion. It is characterized by rupture of capillaries in the skin giving rise to a reddish-blue or purplish colouration of skin (Ecchymosis). (The colouration of the skin, however, is not appreciable in animals with deeply pigmented skin).

3. Haematoma. A haematoma is a collection of blood in an abnormal cavity. It is usually caused by injury to a superficial vein. Haematomas are frequently seen subcutaneously or submucously. The common seats of haematoma in various species are:

Cow: (1) Mammary vein. Cause: Chance of rubbing against the hard ground, butting by the calf. (2) Vaginal mucous membrane. Cause: Injury during copulation.

Bull: Haematoma involving the penis. Cause: Injury during copulation.

Horse: Spur vein or external thoracic vein. Likely cause of injury by the rider.

Dog: (1) Earflap. (2) Vaginal mucous membrane. Cause: Injury during copulation.

Open Wounds

An open wound is a wound in which there is a break in the continuity of skin. Open wounds are classified into the following categories.

1. Incised wounds. Incised wounds are caused by sharp cutting instruments, such as knives, scalpels, fragments of glass etc. An incised wound tends to gape, the extent of gaping depending upon the elasticity and tension of the surrounding tissues. Its edges are regular and there is comparatively less injury to cells. It bleeds freely and may be painful. If the edges are in apposition and the wound is protected from infection it heals by the first intention.

2. Lacerated wounds. A lacerated wound presents torn and uneven edges. Sometimes the skin may be more or less extensively injured and it may be lifted over a wide area from underlying tissues.

3. Punctured wounds. Punctured wounds are caused by sharp pointed objects like nails. They have a relatively small opening and may be very deep. Infection or foreign particles might have been carried deep into the wound. The opening is inadequate for drainage. Example: Punctured wounds on foot due to gathered nail.

4. Penetrating wounds. These are deep wounds communicating with cavities like abdomen, thorax, joints, larynx, trachea, etc. Example: Stab wounds.

5. Perforating wounds. A perforating wound has two openings, one of entrance and the other of exit, e.g., perforating wounds of neck, leg, thorax, abdomen, head etc. _ Note: The terms "perforating wounds" and "penetrating wounds" are sometimes used synonymously.)

6. Gunshot wounds. These are produced by various types of firearms. The point of entrance of the bullet is marked by a smaller opening on the skin but the course of the bullet in deeper tissues exhibits more extensive damage.

7. Abrasions. Abrasions are wounds in which the superficial layers of skin only are removed.

8. Avulsions (Evulsions). An avulsion is a wound in which there is actual loss of tissue. Examples: evulsion of hoof, evulsion of horn.

9. Aseptic wound. It is a surgical wound made under aseptic conditions wherein the chance of bacterial contamination is practically avoided.

10. Contaminated wounds. A contaminated wound is a wound in which microorganisms are present. Strictly speaking, all wounds other than aseptic wounds are contaminated wounds. Infected wounds (Septic wounds). An infected wound is a wound in which microorganisms have invaded the tissues and have started multiplying and producing toxins. (A contaminated wound may become infected after a "lag period" of six to eight hours).

11. Granulating wounds. A granulating wound is a wound which is showing a tendency to heal.

12. Ulcerating wounds. An ulcerating wound is a wound which has no tendency to heal.