Veterinary Wound Management

Wound Management

• The first step in wound management is to control the bleeding.
• Evaluate the wound by location, size, and depth.
• Check for exudate/drainage, presence of tissue, and evidence of infection.
• Cover with a clean, dry bandage ASAP until treatment.
• Clip the hair around the area after applying sterile lube, eye ointment, or moist sterile gauze.
• Lavage at least 7 PSI using a 35-60ml syringe with an 18G needle.
• Gently scrub the outer edges of the wound with no introduction of contaminants.
• Povidone-iodine and chlorhexidine are beneficial, but alcohol should not be used.

Lavage Solutions

• Isotonic fluids are a good option.
• Hydrogen peroxide (<3%) can damage tissues due to its foaming effect, and it is not ideal.
• Chlorhexidine (0.05%) is a broad-spectrum antimicrobial with a long-lasting residue that is not inactivated by organic material.
• Povidone-iodine (1-2%) is a broad-spectrum antimicrobial that lasts 4-6 hours, but it will be inactivated by blood, exudates, and organic material.

Debridement

• Removal of foreign material and dead or damaged tissue from a wound.
• Performed to clean a dirty wound.
• Mechanical debridement involves surgical instruments, dressings, or irrigation.
• Nonmechanical debridement uses enzymatic agents or chemicals.
• Debridement should be performed aseptically.

Drainage

• Relieves buildup of fluid or air.
• Reduces formation of hematoma/seroma, tissue pockets, and dead space.
• Indicated for abscesses, probable contamination, and concerns for air or fluid buildup.
• Penrose surgical drains are made of soft, latex rubber.
• Penrose surgical drains should be removed after 3-5 days.

Acute vs. Chronic Wounds

• Acute wounds have a sudden onset and heal normally.
• Examples of acute wounds include trauma and surgical incisions.
• Chronic wounds are persistent and long-term, taking months or years to heal.
• Examples of chronic wounds include decubital ulcers, or wounds on joints or foot pads.

Wound Contamination

• All wounds are contaminated by microorganisms in the environment.
• Microorganisms are loosely attached to tissues and don't cause an immune response.
• Infection occurs when microorganisms multiply and infect surrounding tissues, triggering an immune response.
• If a wound is >12 hours old, it may be considered "infected"

Types of Wounds

• Puncture wound: Penetration by a sharp object that causes contamination, deep tissue damage, and potential bacteria.
• Laceration: Tearing of tissue resulting in irregular, jagged edges with minimal trauma.
• Abrasion: Rubbing or scraping the skin or mucous membrane.
• Avulsion: Tearing of tissue from its attachment and may create a flap.

Phases of Wound Healing

• Occurs as a series of overlapping events, and more than one phase may occur at a time.
• Inflammatory phase
• Debridement phase
• Repair phase
• Maturation phase

Inflammatory Phase

• Begins immediately after injury and lasts 3-5 days.
• Characterized by the formation of a blood clot and a scab to prevent further hemorrhage.
• Increased blood flow and transudate at the injured site cause heat, redness, and swelling.

Debridement Phase

• It begins around six hours post-injury and lasts up to 3-5 days as part of the inflammatory phase.
• Influx of WBCs to remove necrotic tissue, bacteria, and foreign bodies.
• Neutrophils arrive first, with the ability to be present for the first 6-24 hours.
• Monocytes arrive at 3-5 days and become macrophages once in the wound.
• Macrophages attract fibroblasts.
• Collagen is needed for strength.
• Formation of exudate, which is fluid & WBCs.

Repair Phase

• Starts 3-5 days after injury, lasting 2-4 weeks depending on on the debridement phase.
• Fibroblasts invade the wound.
• The 3 main events consist of angiogenesis, granulation tissue formation, and epithelialization.
• Fibroblasts produce collagen resulting in future scar tissue with strength.
• New capillaries, fibroblasts & fibrous tissue leads to granulation tissue.
• Red fleshy material is present under the scab.
• Granulation tissue is an effective barrier to minimize infection

Epithelialization

• Starts 4-5 days post-injury.
• Epithelial cells divide and migrate across granulation tissue and thickens over time.
• Wound contraction is visible starting 5-9 days post-injury.

Maturation Phase

• Begins approximately 3 weeks post-injury and may take weeks to years to complete.
• Maximum wound strength is achieved.
• Remodeling and crosslinking of collagen fibers and fibrous tissue occurs.

Wound Classification

• Determined according to the degree of contamination present.
• Clean Wound: Not created by trauma.
• Clean-contaminated Wound: Entry of contamination from a controlled environment, contamination is minimal and can be removed.
• Contaminated Wound: Results in increased bacterial contamination from trauma or aseptic surgical technique.
• Dirty/Infected Wound: Obvious signs of infection are present due to a traumatic old wound, purulent discharge, and necrotic tissues.

Wound Closure

• Selected by the nature of the wound.
• Primary closure: Closed immediately.
• Delayed primary closure: Closed several days after injury.
• Secondary closure: Formation of granulation tissue.
• Secondary intention: Not surgically closed.
• Primary closure is used when healing is uncomplicated.
• Heals recent clean wounds, as well as recent contaminated wounds.

Delayed Primary Closure

• Wound is left open for a few days, protected with dressings, and sutured closed when granulation tissue forms (~1-5 days).
• This is indicated for contaminated/infected wounds, viability of tissue in question, and marked swelling of adjacent tissues.
• Secondary closure happens when the wound is left open, and then it is sutured after approximately 5 days.
• This allows healthy wounds to heal.
• It is indicated when severely contaminated or traumatized wounds require extended wound management.
• Second-intention healing leaves the wound to heal without surgical intervention.

Second-Intention Healing

• Healing occurs from the bottom of the wound upwards.
• May result in scarring and loss of function.
• Indicated in events of severe lacerations, burns, and large amounts of tissue loss.

Factors Affecting Wound Healing

• Host, wound, and external factors.
• Host factors include age, health, nutrition, BCS, concurrent diseases, and activity level.
• Wound factors include the type of the wound, acute vs. chronic, contamination, blood supply, and location.
• External factors include current medications and treatments.
• Dehiscence is the opening of the wound after closure and it can occur if there is too much activity.