WOUND CARE AND HEALING
A. Types of tissue and structures
Outer surface made up of several layers, sweat glands and hair follicles. Skin is nourished by blood vessels and nerves that run below the skin surface radiating out from the heart and spinal cord.
A loose layer of fibrous tissue that connects the skin from the underlying structures. It is an important layer to lend strength when suturing skin. It is also an area for some types of injections.
A strong white fibrous layer that holds muscle bundles together. It is also important in suturing damaged muscle, because muscle fibers themselves do not hold sutures well.
Bundles of fibers called myofilaments which are contractile protein fibers called "actin" and "myosin". These work together to cause all movement in the body.
Strong bundles of fibers which attach muscles to bone.
The same fibers as tendons, but they connect bone to bone.
Where tendons run over bones they are incased in synovial sheaths to allow smooth wear free transfer of action.Penetrating injuries into these structures can be devastating if they result in infection.
These are complex structures where bones are held together by ligaments, the bone ends are covered with cartilage, the whole is incased in a capsule which is lined with synovial tissue. This tissue produces synovial fluid which is a thick, yellow consistency and lubricates the joints. A penetrating injury to a joint may release this fluid, but can also cause an infection in the joint which can spell disaster to the patient.
B. Types of injuries
Abrasions, scrapes or scratches: Superficial injuries that do not penetrate through the skin.
Blunt trauma causing the disruption of capillaries and deeper tissue damage without breaking the skin.
Deep penetrating wounds which often close over after the offending object is removed.
Laceration: A cut through the skin into deeper tissues.
Damage to the tissue from heat, friction or a caustic substance.
A break in the bone may be a hairline or complete disruption of the bone. Can be comminuted where the bone is broken into many pieces or compound which means that the bone breaks through the skin.
C. Terms describing the condition of wounds
The five signs of inflammation are: Heat, Swelling, Redness, Pain and Loss of function.
A wound that has been exposed to infective agents.
The infective agents have started to grow.
A fresh wound with minimal contamination.
Applies only to autoclaved or disinfected surfaces or implements.
D. Types of discharge
Contains all the red and white cells, protein, fibrin and serum. Blood clots when exposed to the air or damaged tissue.
Clear fluid with a yellow tinge from which the cells and fibrin are removed leaving only protein and water.
Pus: Discharge with a large number of white cells present which are fighting infection.
II. CARE OF WOUNDS
A. Type of wounds
Clean gently to remove contamination and debris and apply antibacterial ointment. If flies are an issue, use an antiseptic fly repellent. Repeat as needed.
Apply cold via water or pack and use an anti inflammatory agent per your vet. Continue for five days, then change to hot packs until resolved.
The most important treatment of punctures involves getting them open and draining. If you are able to flush them out with clean water that may be enough, if not your vet needs to open it and if necessary place a drain. These can usually not be closed and need to heal from the inside out. Antibiotics may be indicated to treat trapped infection.
If the cut is clean, cover it to keep it from drying out and call your vet to try to close it. The window of opportunity to close a wound by primary intention is four hours. If the wound is badly contaminated or swollen, it may need to be allowed to heal by itself, or be freshened up and closed after five days by your vet by second intention closure.
Cool off any burn as quickly as possible and then apply antibacterial ointment. Even if the area is not open initially, it may slough off damaged tissue later.
If you suspect a fracture, stabilize the area with a lot of padding and splints and keep the horse quiet until your vet can get there. Many fractures can be repaired; so don't make any drastic decisions until a professional has evaluated the injury.
B. Control of infection
Whenever a wound exists there will be bacteria to populate it. In most cases the body can fight off the infection with its own defenses. Occasionally we have to help out with the use of antibiotics. Each bacterium has some drugs that it is susceptible to and others to which it is resistant. It is very important to determine the susceptibility of a bug before you start using the drug. If you do not you risk creating more resistant bacteria, that will make it harder to treat the animal the next time. Be sure always to use a specific proper drug, at adequate doses, for a long enough time. This can only be done by doing cultures and sensitivities on any infection.
III. WOUND HEALING
A. Factors effecting wound healing
In order for tissue to heal it requires a good blood supply. If the injury has interrupted the blood supply to the wound there may be an area of tissue that dies. This tissue will not hold sutures and will need to be sloughed before healing can occur. This will cause a wound that has been sutured to fall apart, usually at a about a week.
In order for muscle to remain viable and useful it needs a nerve supply. Any injury can cause nerve damage and may influence the final outcome of healing.
Despite cleaning and antibiotics, sometimes a wound will become infected anyway, causing the wound to dehisce or fall apart.
If there is movement in a wound between the two sides, the wound cannot heal. There needs to be good stability across the repair, whether it is skin, muscle or bone. For example, sutures placed over a joint are often unsuccessful.
B. How wounds heal
Blood carries all the necessary materials to a wound to clean it up and heal it. At first white cells carry away any debris and contamination. Then fibrin is laid down in the wound, which binds the two sides together. As the fibrin matures, it pulls the sides closer, eventually binding them with a solid scar. At the same time, after a weeklong lag period, new blood vessels grow into the defect, further supporting the healing process. When too much healing occurs and it bubbles up over the skin edges it is called "proud flesh". This must be controlled and kept below the skin edges so that the skin can close over the wound.