Wound management

Chapter 6
Wound management

Patients come to the veterinary hospital with a huge variety of wounds. They range from simple scrapes to burns and huge gaping contaminated injuries. While basic wound management starts the same for any injury, the extent of care varies greatly. A Labrador Retriever with a pad laceration from stepping on a piece of glass needs far different care than a Chihuahua attacked by a Mastiff causing bite wounds and internal abdominal damage or a cat caught in a house fire. Postoperatively and sometime preoperatively, patients require wound and surgical incision care that may include drains, bandages, and external coaptation. The veterinary technician is an integral part of the team in daily (or more frequent) assessment of patients’ wounds. A wound is damage to the skin and underlying structures (Hosgood 2012). There are many types of injuries.

Types of wounds

  • Abrasion: Although painful, abrasions are less than full skin thickness deep, have a minimal amount of bleeding, and heal quickly with little intervention
  • Puncture: Full penetrating injury, punctures go deep into the tissues through a small opening resulting in contamination and destruction – examples include stick penetration, bite, and gunshot wounds
  • Laceration: Sharp skin edges characterize lacerations although the edges may be ragged, they may be deep or superficial, and include surgical incisions
  • Degloving: Much skin and underlying tissue is lost or torn away thus severing the blood supply, most often found on distal limbs
  • Burn: Resulting from a heat source near or directly on the skin, burns vary in severity: superficial partial (epithelial), deep partial (epithelial and partial dermal), and full thickness, burns may worsen in severity over time due to delayed microvascular damage
  • Decubital ulcer: A compression injury, decubital ulcers form when skin and soft tissues are compacted between a bony prominence (e.g., elbow, hock, and hip) and a hard surface (e.g., deficiently padded bed), tissue damage can be extensive and is most common in recumbent patients

Phases of wound healing (Cornell 2012)

Wounds follow a specific pattern of healing. (Table 6.1)

Table 6.1 Wound healing chronology.

Time Wound
1–3 d Cellular debridement, inflammation in minimally traumatized (ideal) wound
3–5 d Granulation bed forming and visible
7 d Collagen deposition increases, minimal increase in wound strength
7–14 d Rapid increase in wound strength
14 d Wound begins to strengthen
6 wk Full contracture of properly managed wound
Months to years Scar maturation; gradual strengthening

Jonathan McAnulty, University of Wisconsin-Madison, Madison, WI. Reproduced with permission from Jonathon McAnulty.

  1. Inflammation: When a wound occurs, inflammation begins. Endothelin protein is produced along with other mediators; it initially causes vasoconstriction. The coagulation cascade begins to create hemostasis. Thrombin and growth factors attract cells to the site to begin wound healing. Neutrophils and macrophages travel to the wound within 24–48 hours to remove bacteria. These cells die as they ingest material and produce fluid. This is the purulent material seen in wounds. (Figure 6.1) Soon after, prostaglandins, histamine, and other factors initiate vasodilation and increased blood flow to the area. This creates the characteristic inflammatory signs of redness, heat, and swelling.
  2. Proliferation: This constructive phase begins after wound debridement and from about day four through day twelve following injury. It is delayed when foreign material, infection, necrotic debris, or a hematoma is present. The scope of the wound, its location, and patient condition influences the duration of this period. Capillaries grow into the wound from surrounding vasculature, collagen is produced and the wound contracts and eventually closes. A network of small blood vessels within the wound provides oxygen and nutrients and eventually develops into granulation tissue, which is very resistant to infection (Figure 6.2).
  3. Maturation: The remodeling and strengthening phase is the longest; primarily it begins in 5–9 days and lasts 4–5 weeks but can extend to eighteen months. During this time, the initial type of collagen changes and becomes stiffer, stronger, and thicker collagen. If continual bending occurs at the wound site, such as over a joint, this phase of healing is prolonged. The initial collagen continues production and abnormal healing may occur by contracture causing decreased function of the joint (Figure 6.3).

Figure 6.1 Phase 1 of wound healing is characterized by inflammation, redness and purulent material accumulating within the wound from cell death.

(Robert Hardie, University of Wisconsin Veterinary Care. Madison, WI. Reproduced with permission from Robert Hardie.)


Figure 6.2 Phase 2 of wound healing includes proliferation of tissue and granulation bed formation.

(Robert Hardie, University of Wisconsin Veterinary Care. Madison, WI. Reproduced with permission from Robert Hardie.)


Figure 6.3 Phase 3 of wound healing is the maturation of the cells as collagen forms and strengthens while the wound continues to shrink in size.

(Robert Hardie, University of Wisconsin Veterinary Care. Madison, WI. Reproduced with permission from Robert Hardie.)

Delays in wound healing

In addition to contamination with foreign material, infection, and necrotic tissue, other factors can affect wound healing. Patients’ general conditions can delay injury healing. Systemic disorders such as diabetes, Cushing’s disease, chronic steroid use, renal and liver disease, cancer, starvation, chemotherapy, and so on all affect a patient’s ability to heal. Wounds must be well perfused to provide oxygen critical to healing. Systemic antibiotics cannot reach the injury without sufficient blood flow. Shock and hypotension as well as arterial and venous impairment limit hemoglobin (oxygen) delivery to the wound. Hematomas and seromas impair healing by physical disruption, increased pressure on the wound bed, increasing dead space and providing an ideal environment for bacterial growth. Large wounds heal slower due to the greater affected surface area than smaller wounds. Partial wound closure, where appropriate, reduces this factor.

Good surgical techniques can decrease delays in healing. These include minimizing tissue trauma, minimizing debris, maintaining moist tissues, minimizing surgical time, avoiding tension on the wound (incision), and providing drainage as needed. Factors that can increase surgical wound infection are many.

  1. Bacterial contamination: Surgeries are classified according to their likelihood of infection, (Mangram et al 1999) higher classifications have a much-increased chance of postoperative complications. Wounds are classified as:

    1. Clean: no trauma, infection or inflammation and respiratory, gastrointestinal, genitourinary, and oropharyngeal cavities are not entered – infection rate: 2–4.8%
    2. Clean-Contaminated: respiratory, gastrointestinal, genitourinary, and oropharyngeal cavities are entered under controlled conditions – infection rate: 3.5–5%
    3. Contaminated: open, fresh, accidental wounds, operations with major breaks in sterile technique or gross spillage from gastrointestinal tract – infection rate: 4.6–12%
    4. Dirty-Infected: old traumatic wounds with devitalized tissue, existing clinical infection, foreign bodies, perforated colon, infective organism present prior to surgical procedure – infection rate: 6.7–18.1% (National Research Council Wound Classification System 2012).

  2. Propofol use (Brown 2012a): Lipid-based emulsions may support microbial growth. Prompt use of prepared syringes of propofol and avoiding the use of the same syringe on multiple patients decreases this source of infection.
  3. Operating room personnel: Inadequate aseptic technique and increased number of personnel in the surgical suite increases the source of contamination.
  4. Patient’s sex: Intact males produce androgenic hormones leading to immunomodulation (Brown 2012b).

Despite best surgical practices, surgical wound infection remains a concern in small animal hospitals. The United States Centers for Disease Control created guidelines defining surgical site infection (SSI) (Table 6.2).

Table 6.2 Centers for Disease Control criteria for defining a surgical site infection (SSI).

Type of infection Timing Infected tissue Signs – at least one present
Superficial incisional SSI Within 30 d of surgery Skin or subcutaneous

  1. Superficial purulent discharge
  2. Positive culture
  3. Pain, tenderness, swelling, redness or heat
Deep incisional SSI Within 30 d of surgery or 1 year if implant in place and infection related to procedure Deep soft tissue of incision: fascia or muscle

  1. Deep purulent discharge
  2. Incision spontaneously dehisces
  3. Abscess present in deep tissue
Organ/space SSI Within 30 d of surgery or 1 year if implant in place and infection related to procedure Any part of anatomy opened or manipulated during surgery excluding incision

  1. Purulent drainage from drain placed into organ or space
  2. Positive culture
  3. Abscess present in organ/space

Data from Mangram et al. (1999).

General wound care

Upon admittance, along with evaluating the entire patient, an assessment is made of the patients’ wounds for degree and duration of injury. Patient’s life-threatening injuries are always addressed first including the ABCs – Airway, Breathing and Circulation. Despite the initial reaction to want to manage huge gaping wounds, even these do not generally require immediate attention unless the patient is hemorrhaging.

The facilitation of healing without infection is the goal of wound management. Contamination is the presence of bacteria on the surface of a wound. If unattended, this leads to colonization where the microbes are increasing. If still not addressed, colonization becomes infections where the bacteria and other organisms invade the tissues. Class 1 wounds are less than 6 hours old with minimum contamination and trauma. These first 6 hours are the golden period where there are an insufficient number of microbes to cause infection. Class 2 wounds, 6–12 hours old, show organism replication but they may not have reached the critical level (105 colony forming units(CFU) per gram of tissue) to create infection. Class 3 wounds of greater than 12 hours show great bacterial and other organism growth and develop infection.

First intention healing occurs when the surgeon primarily closes

Dec 15, 2022 | Posted by in NURSING & ANIMAL CARE | Comments Off on Wound management
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