BCSE Surgery

Wound Management – BCSE Study Guide

Wound management is a foundational skill for every veterinarian. Whether treating surgical incisions, traumatic lacerations, or chronic non-healing wounds, understanding the principles of wound classification, healing phases, closure techniques, and

Overview and Clinical Importance

Wound management is a foundational skill for every veterinarian. Whether treating surgical incisions, traumatic lacerations, or chronic non-healing wounds, understanding the principles of wound classification, healing phases, closure techniques, and bandaging is essential for optimal patient outcomes. This topic integrates anatomy, physiology, pharmacology, and surgical technique into practical clinical application.

On the BCSE, wound management questions often present clinical scenarios requiring you to select the appropriate closure method, identify factors delaying healing, or choose the correct bandaging technique. Expect questions that integrate concepts across multiple domains.

High-YieldWound management questions frequently appear in both the Surgery domain AND the Medicine domain. Understanding these principles will help you answer questions across multiple sections of the exam.
Class Description Examples SSI Risk
Class I: Clean Surgical incisions made under aseptic conditions. Does NOT enter GI, respiratory, or urogenital tracts. No inflammation present. Primary closure used. Spay/neuter, orthopedic procedures, inguinal hernia repair, thyroidectomy 1-5%
Class II: Clean-Contaminated Controlled entry into GI, respiratory, or urogenital tract without significant spillage. Minor break in technique. Cystotomy, gastrotomy, cholecystectomy, elective GI surgery 3-11%
Class III: Contaminated Fresh traumatic wounds (less than 6 hours old). Major break in aseptic technique. Gross spillage from GI tract. Acute non-purulent inflammation. Recent gunshot wounds, recent lacerations, enterotomy with spillage 10-17%
Class IV: Dirty/Infected Old traumatic wounds (greater than 12 hours). Clinical infection present. Perforated viscus. Necrotic tissue, pus, or fecal contamination. Perforated bowel, abscess drainage, bite wounds with purulent discharge Greater than 27%
Wound Type Description Clinical Considerations
Abrasion Loss of epidermis and partial dermis due to friction Painful, low infection risk, heals by epithelialization
Laceration Irregular wound from tearing force, variable depth Requires thorough exploration for underlying damage
Puncture Penetrating wound from sharp object, minimal skin damage HIGH infection risk - assess for deep tissue damage and foreign bodies
Avulsion/Degloving Tissue torn away from underlying structures Often requires delayed closure, skin grafting, or second intention healing
Incision Clean-edged wound made by sharp instrument Best prognosis for primary closure when created aseptically

Section 1: Wound Classification

The surgical wound classification system, originally developed by the National Research Council and refined by the CDC, categorizes wounds based on their bacterial contamination level. This system predicts surgical site infection (SSI) risk and guides antibiotic prophylaxis decisions.

The Four Wound Classes

Memory Aid - "Clean Contamination Can Devastate" (Classes I-IV)

Class I = Clean (1-5% risk), Class II = Clean-Contaminated (3-11%), Class III = Contaminated (10-17%), Class IV = Dirty (greater than 27%). Remember: Risk roughly DOUBLES with each class!

High-YieldThe "Golden Period" is traditionally defined as less than 6 hours post-injury when bacterial counts remain below 10^5 organisms per gram of tissue. However, this varies by wound location - head and face wounds have better blood supply and may be safely closed up to 24-48 hours post-trauma.

[Include Image: Figure 1. Wound Classification Diagram showing the four classes with representative examples]

Source: Wikimedia Commons - https://commons.wikimedia.org/wiki/Category:Wound_classification (CC BY-SA)

Open vs. Closed Wound Types

Memory Aid - "A-L-P-A-I" for Open Wound Types

Abrasion (scrape), Laceration (tear), Puncture (poke), Avulsion (rip away), Incision (cut). Remember: Punctures look small but can be DEEP - always explore!

Stage Events Key Cells/Mediators
Hemostasis (Immediate) Vasoconstriction (brief), platelet aggregation, clot formation, fibrin matrix created Platelets release PDGF, TGF-beta, thrombin
Chemotaxis (Minutes-Hours) Vasodilation, increased vascular permeability, leukocyte migration into wound Neutrophils (first 24-48 hours)
Debridement (Hours-Days) Phagocytosis of bacteria and debris, release of cytokines and growth factors Macrophages become dominant (48 hours+), ESSENTIAL for healing
Process Description Clinical Relevance
Fibroplasia (Collagen Formation) Fibroblasts migrate into wound and produce collagen (initially Type III, later replaced by Type I) Wound strength increases - collagen provides structural support
Angiogenesis (Neovascularization) New capillary growth into wound bed from existing vessels Granulation tissue is highly vascular, friable, and resistant to infection
Epithelialization Epithelial cells migrate across wound from edges, stop when contact other cells (contact inhibition) Requires healthy granulation bed. Closed incisions re-epithelialize in 48 hours
Wound Contraction Myofibroblasts cause wound edges to move centripetally at approximately 0.6-0.75 mm/day Major mechanism for open wound closure. Slows dramatically after 6 weeks

Section 2: Wound Healing Phases

Wound healing is a complex, overlapping process divided into three principal phases. Understanding these phases is essential for selecting appropriate wound management strategies and recognizing when healing is impaired.

[Include Image: Figure 2. Wound Healing Phases Timeline showing overlap of inflammatory, proliferative, and remodeling phases]

Source: Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Wound_healing_phases.png (CC BY-SA 3.0)

Phase 1: Inflammatory Phase (Days 0-5)

The inflammatory phase begins immediately after injury and is characterized by hemostasis followed by inflammation. This phase prepares the wound for repair.

Key Events in the Inflammatory Phase

Memory Aid - "STOP the Bleeding, CLEAN the Mess" for Inflammatory Phase

STOP = Hemostasis (Stop bleeding via clotting). CLEAN = Chemotaxis and debridement (Leukocytes arrive to clean up). The cardinal signs of inflammation (Rubor, Calor, Tumor, Dolor, Functio Laesa) are visible during this phase.

High-YieldMACROPHAGES are ESSENTIAL for wound healing - they secrete growth factors that recruit fibroblasts and mesenchymal cells. Neutrophils phagocytose bacteria but are NOT essential for wound strengthening.

Phase 2: Proliferative Phase (Days 3-21)

Also called the repair phase, this phase involves rebuilding the wound with new tissue. Three key processes occur simultaneously: granulation tissue formation, wound contraction, and epithelialization.

Memory Aid - "FACE" the Proliferative Phase

F = Fibroplasia (collagen production), A = Angiogenesis (new blood vessels), C = Contraction (wound shrinks), E = Epithelialization (skin coverage). All four processes work together to rebuild the wound!

[Include Image: Figure 3. Healthy granulation tissue appearance - pink, granular, bleeds easily]

Source: PubMed Central Open Access - https://pmc.ncbi.nlm.nih.gov/articles/PMC4663678/ (CC BY)

High-YieldHealthy granulation tissue is PINK, MOIST, GRANULAR, and BLEEDS EASILY. It is resistant to infection due to rich vascularization. If granulation tissue appears pale, dry, or does not bleed, the wound may have impaired blood supply.

Phase 3: Remodeling/Maturation Phase (Day 21 - Up to 2 Years)

The final phase involves reorganization and strengthening of the wound. Type III collagen is gradually replaced by Type I collagen, and the scar tissue matures.

  • Type III collagen (30% in early healing) is replaced by Type I collagen (restoring normal 80-90% composition)
  • Collagen fibers reorganize along lines of tension
  • Wound NEVER regains full strength - maximum 80% of original tissue strength
  • Vascularity decreases, scar becomes paler and flatter over time

Memory Aid - "3-1-80" Rule for Remodeling

Type 3 collagen is replaced by Type 1 collagen, and the wound reaches 80% maximum strength. Remember: A healed wound is NEVER as strong as the original tissue!

High-YieldSutures in normally healing wounds can typically be removed in 10-14 days. In areas of high tension or in patients with delayed healing, sutures may be left longer or alternate sutures removed first.
Closure Type Description Indications Timing
Primary Closure (First Intention) Immediate surgical closure of wound edges after debridement and lavage Clean wounds, clean-contaminated wounds, fresh traumatic wounds after adequate debridement Within 6 hours (Golden Period) or up to 24-48 hours for well-vascularized areas
Delayed Primary Closure (Third Intention) Wound left open for 3-5 days for management, then surgically closed BEFORE granulation tissue forms Contaminated wounds, questionable tissue viability, moderate trauma Days 2-5 post-injury
Secondary Closure Surgical closure AFTER granulation tissue has formed. Granulation tissue and epithelialized edges are excised before closure Dirty wounds converted to clean after granulation, wounds with significant tissue loss 5+ days post-injury (after healthy granulation)
Second Intention Healing Wound left open to heal by granulation, contraction, and epithelialization without surgical closure Grossly contaminated wounds, wounds with significant tissue loss, distal limb wounds where closure would cause excessive tension Weeks to months depending on wound size
Material Type Absorption Advantages Common Uses
Chromic Catgut Natural, absorbable 10-40 days (enzymatic) Good handling, inexpensive GI surgery, vessel ligation (less common now)
Polyglycolic Acid (Dexon) Synthetic, absorbable, braided 60-90 days (hydrolysis) Predictable absorption, good knot security Subcutaneous, fascia
Polyglactin 910 (Vicryl) Synthetic, absorbable, braided 56-70 days (hydrolysis) Good tensile strength, minimal tissue reaction Subcutaneous, linea alba, vessel ligation
Poliglecaprone (Monocryl) Synthetic, absorbable, monofilament 91-119 days (hydrolysis) Smooth passage, minimal tissue reaction Intradermal, subcuticular
Polydioxanone (PDS) Synthetic, absorbable, monofilament 180+ days (hydrolysis) Long-lasting support, excellent for slow-healing tissues Fascia, tendon, bladder
Nylon (Ethilon) Synthetic, non-absorbable, monofilament Non-absorbable Smooth, minimal tissue reaction, good knot security Skin closure
Polypropylene (Prolene) Synthetic, non-absorbable, monofilament Non-absorbable Inert, maintains strength, slides easily for pull-out sutures Cardiovascular, skin
Silk Natural, non-absorbable, braided Loses strength by 1 year, may be absorbed eventually Excellent handling and knot security GI surgery, vessel ligation (avoid in contaminated wounds)
Stainless Steel Metal, non-absorbable, monofilament Non-absorbable Strongest, inert, maintains strength indefinitely Orthopedic, sternal closure

Section 3: Wound Closure Techniques

Selecting the appropriate wound closure method is critical for successful healing. The choice depends on wound classification, contamination level, tissue viability, location, and time since injury.

Types of Wound Closure

Memory Aid - "1-3-2-2" for Closure Types

First intention (1) = Primary closure, Third intention (3) = Delayed primary closure, Secondary = Close AFTER granulation (2nd chance), Second intention = Let it heal on its own (2). The numbers help you remember which comes when!

High-YieldAlmost ANY wound can be considered for primary closure IF adequate debridement, lavage, and cleansing have been performed. However, just because you CAN close a wound does not mean you SHOULD - always assess contamination level, tissue viability, and tension.

[Include Image: Figure 4. Comparison of healing by first intention vs second intention showing different tissue organization]

Source: Wikimedia Commons - https://commons.wikimedia.org/wiki/Category:Wound_healing (CC BY-SA)

Suture Material Selection

Memory Aid - "Natural = Enzyme, Synthetic = Water" for Absorption

Natural sutures (catgut, silk) are broken down by ENZYMES (phagocytosis/proteolysis). Synthetic sutures (Vicryl, PDS, Monocryl) are broken down by WATER (hydrolysis). Hydrolysis is more predictable!

Memory Aid - "Mono = Smooth, Braided = Grip" for Suture Structure

Monofilament sutures (PDS, Monocryl, Nylon, Prolene) pass smoothly through tissue but have more memory. Braided sutures (Vicryl, Silk) have better handling and knot security but more tissue drag and potential for bacterial wicking.

High-YieldAVOID braided sutures (silk, Vicryl) in contaminated wounds - the interstices can harbor bacteria. Use monofilament sutures instead.

Common Suture Patterns

[Include Image: Figure 5. Suture pattern diagrams showing simple interrupted, continuous, horizontal and vertical mattress patterns]

Source: Wikimedia Commons - https://commons.wikimedia.org/wiki/Category:Suture_patterns (CC BY-SA)

Memory Aid - "APPOSITIONAL vs. EVERTING vs. INVERTING"

Appositional patterns (simple interrupted, simple continuous) bring edges together evenly. Everting patterns (mattress sutures) turn edges outward - good for skin under tension. Inverting patterns (Lembert, Cushing) turn edges inward - REQUIRED for hollow organs to create watertight seal.

High-YieldFor GI surgery, use a two-layer closure: Inner layer (simple continuous through all layers) + Outer layer (Lembert or Cushing inverting pattern). The submucosa is the holding layer of the GI tract.

Memory Aid - Suture Spacing Rule

Place sutures 3-5mm from wound edge, spaced 6-10mm apart (approximately twice the bite distance). Sutures placed too close together can compromise blood supply and delay healing.

Pattern Characteristics Advantages Common Uses
Simple Interrupted Individual sutures, each tied separately. Appositional pattern. Tension adjustable per suture, if one fails others hold, versatile Skin, most tissues, gold standard
Simple Continuous Single strand, knotted only at beginning and end. Appositional pattern. Faster, less suture material, even tension distribution Subcutaneous, fascia, linea alba
Ford Interlocking Continuous pattern with each loop locked. Appositional pattern. More secure than simple continuous, easier to keep neat Skin closure in large animals
Horizontal Mattress Sutures parallel to wound edge. Everting pattern. Tension-relieving. Good for tension, provides eversion of wound edges Areas of tension, fascia, skin under tension
Vertical Mattress Sutures perpendicular to wound edge (far-far, near-near). Everting pattern. Excellent skin edge apposition, tension relief Skin closure under tension
Cruciate (Cross) X-shaped interrupted pattern More efficient than simple interrupted, good for non-linear wounds Skin, large animal skin closure
Subcuticular/Intradermal Continuous pattern within dermis, no external suture visible Cosmetic, no suture removal needed if absorbable Skin closure when cosmesis important
Lembert Inverting pattern, does not penetrate lumen. Bites perpendicular to incision. Creates watertight seal, inverts tissue Hollow organ closure (stomach, intestine, bladder)
Cushing Continuous inverting pattern, bites parallel to incision Rapid, inverting, does not penetrate lumen Second layer of GI closure, uterus
Layer Function Materials Application Tips
PRIMARY (Contact Layer) Direct contact with wound. Debridement (adherent) or protection (non-adherent). May deliver topical medications. Non-adherent: Telfa pads, petroleum gauze. Adherent: wet-to-dry gauze, saline-soaked gauze. Specialized: silver alginate, hydrogels, foams Apply STERILE for open wounds. Choose based on wound needs (debridement vs protection). Always place over wound FIRST.
SECONDARY (Absorbent Layer) Absorbs exudate. Provides padding and comfort. Supports primary layer. Adds compression. Cast padding, rolled cotton, Webril. Conforming gauze (Kling, Kerlix) applied over padding. Apply with 50% overlap. Work distal to proximal. DO NOT apply too tight - padding should rip before compressing.
TERTIARY (Outer Layer) Protects inner layers from environment. Holds bandage in place. Provides final compression. Vetrap, Elastikon, Coban, elastic adhesive tape Apply with 50% overlap. Avoid excessive tension. Leave toes visible to monitor for swelling.

Section 4: Bandaging and Wound Care

Proper bandaging protects wounds from contamination, absorbs exudate, provides compression, and creates an optimal healing environment. Understanding the three-layer bandaging system and proper application technique is essential for veterinary practice.

The Three-Layer Bandaging System

Memory Aid - "PST" for Bandage Layers (Primary-Secondary-Tertiary)

P = Primary touches Patient (wound contact). S = Secondary Sucks up fluid (absorption). T = Tertiary Ties it all together (protection). Remember inside to outside: PST!

High-YieldWet-to-dry bandages are a form of MECHANICAL DEBRIDEMENT - the gauze adheres to necrotic tissue and removes it when the bandage is changed. Do NOT rehydrate the bandage before removal if debridement is desired. This technique is now considered less ideal than moist wound healing for most situations.

Modified Robert Jones Bandage

The modified Robert Jones (MRJ) bandage is the most commonly used bandage in small animal practice for limb wounds. It provides moderate support, compression, and wound protection.

[Include Image: Figure 6. Step-by-step application of Modified Robert Jones bandage showing stirrup placement, padding, and final wrapping]

Source: Open Educational Resources - https://oercommons.org/courseware/lesson/114360/overview (CC BY)

MRJ Application Steps

  • Place patient in lateral recumbency with affected limb up
  • Apply TAPE STIRRUPS to lateral and medial aspects of limb, extending beyond digits. Attach to tongue depressor.
  • Apply PRIMARY LAYER sterile dressing over wound if present
  • Apply CAST PADDING (secondary layer) from distal to proximal with 50% overlap. Leave middle toes visible. 4-8 layers depending on support needed.
  • Apply CONFORMING GAUZE over padding with mild compression, distal to proximal
  • Twist tape stirrups 180 degrees and adhere to outside of gauze layer
  • Apply TERTIARY LAYER (Vetrap or elastic tape) with 50% overlap. Leave toes exposed for monitoring.

Memory Aid - "STIR-PAD-WRAP" for MRJ Application

STIR = Stirrups first (anchor the bandage), PAD = Padding goes next (cast padding + gauze), WRAP = Wrap it up (tertiary layer). Always work DISTAL to PROXIMAL to encourage venous return!

High-YieldThe middle two toes (digits 3 and 4) should ALWAYS be visible at the distal end of a limb bandage. This allows monitoring for swelling, coldness, or discharge that indicates the bandage is too tight or infection is present.

Tie-Over Bandage

Tie-over bandages are used for wounds in locations that cannot be easily wrapped (axilla, inguinal region, hip, head, trunk). Stay sutures are placed around the wound periphery, and umbilical tape is woven through to secure bandage materials.

[Include Image: Figure 7. Tie-over bandage showing stay sutures placed circumferentially around wound with umbilical tape securing dressing]

Source: PubMed Central - https://pmc.ncbi.nlm.nih.gov/articles/PMC4663678/ (CC BY)

Bandage Monitoring and Complications

Memory Aid - "STS" for Bandage Emergencies

Swelling = Too tight, must remove immediately. Too wet (strike-Through) = Bacteria can enter, change now. Slippage = Reapply correctly. STS reminds you of the 3 main reasons to change a bandage ASAP!

High-YieldA bandage that becomes WET must be changed immediately. Wet bandages lose their absorptive capacity, promote bacterial growth, and can cause maceration of underlying tissue. Instruct clients to use waterproof covers when pets go outside.
Complication Signs Management
Too Tight Toe swelling, divergence of toes, coldness, pain, decreased capillary refill IMMEDIATELY remove and replace. Can cause ischemic necrosis, digit loss
Slippage Gap visible between bandage and skin, bandage migrates distally Replace bandage, ensure adequate stirrup placement, consider different technique
Strike-through Fluid visible on outer layer of bandage Change bandage immediately - strike-through allows bacterial migration INTO wound
Pressure Sores Tissue damage over bony prominences (carpus, hock, elbow) Add donut padding over prominences, avoid wrinkles, check bandage daily
Self-Trauma Patient chewing or scratching at bandage Apply Elizabethan collar, use bitter spray, address underlying pain or pruritus
Factor Effect on Healing Management
Infection (greater than 10^5 organisms/g tissue) Prolongs inflammatory phase, disrupts clotting, impairs fibroblast function, degrades collagen Debridement, lavage, culture and sensitivity, appropriate antibiotics
Foreign Material Perpetuates inflammation, provides nidus for bacteria, prevents closure Thorough exploration, debridement, radiography to identify
Necrotic Tissue Provides medium for bacterial growth, prevents granulation Surgical or autolytic debridement until healthy tissue reached
Poor Blood Supply Impairs delivery of oxygen, nutrients, and immune cells to wound bed Minimize tension, avoid tight bandages, consider location when planning closure
Excessive Tension Compromises blood flow, increases risk of dehiscence Tension-relieving suture patterns, undermining, walking sutures, skin flaps
Movement/Motion Disrupts granulation tissue formation, prevents epithelialization Appropriate immobilization, bandaging, activity restriction
Desiccation (drying) Causes cell death, impairs epithelial migration Moist wound healing with appropriate dressings
Wound Location Distal limb wounds heal slower than head/trunk due to poor blood supply Plan for longer healing times, consider second intention healing for distal limb

Section 5: Factors Affecting Wound Healing

Multiple local and systemic factors can impair wound healing. Identifying and addressing these factors is essential for managing non-healing or delayed-healing wounds.

Local Factors

Memory Aid - "IN FM DBM" for Local Factors

I = Infection, N = Necrotic tissue, F = Foreign material, M = Movement, D = Desiccation, B = Blood supply (poor), M = Motion/mechanical forces. These are the local enemies of wound healing!

Systemic Factors

Drug Effects on Wound Healing

Memory Aid - "MAUD-CO" for Systemic Healing Factors

M = Malnutrition, A = Anemia, U = Uremia, D = Diabetes, CO = Corticosteroids (drugs). These systemic factors all DELAY healing - think of "maudlin" (sad/depressed) as in your wound will be "sad" and not heal!

High-YieldCORTICOSTEROIDS have the MOST significant drug effect on wound healing. They inhibit virtually every phase of healing. Vitamin A (topically or systemically) can partially counteract corticosteroid effects on wound healing.

Nutritional Requirements for Healing

Memory Aid - "Wounds CRAVE Good Nutrition" for Nutrients

C = Vitamin C (collagen hydroxylation), R = (iron) for RBCs and oxygen transport, A = Vitamin A (epithelialization), V = (copper) for cross-linking (Validation of collagen), E = Energy from glucose. Plus Protein and Zinc for cell proliferation!

High-YieldBoth DEFICIENCY and EXCESS of zinc impair wound healing. Zinc deficiency delays epithelialization. Excess zinc inhibits macrophage function and interferes with collagen cross-linking.
Factor Effect on Healing Management
Malnutrition/Hypoproteinemia (TP less than 2 g/dL) Decreased collagen synthesis, impaired fibroplasia, prolonged healing, decreased wound strength, edema Nutritional support, increase protein and calorie intake, address underlying cause
Diabetes Mellitus/Hyperglycemia Impaired leukocyte function, poor tissue perfusion, delayed healing Glycemic control, careful monitoring for infection
Advanced Age Reduced skin elasticity, slower collagen replacement, decreased immune function Allow longer healing times, nutritional support, careful monitoring
Anemia Decreased tissue oxygenation impairs all phases of healing Identify and treat underlying cause, transfusion if severe
Uremia Slows granulation tissue formation, produces poor quality collagen Manage underlying renal disease, fluid therapy
Obesity Decreased blood supply to adipose tissue, poor suture holding in fat Minimize dead space, use appropriate closure techniques for fat
Immunocompromise Impaired inflammatory response, increased infection risk Address underlying cause, strict aseptic technique, antimicrobial prophylaxis
Drug Class Effect on Healing Clinical Consideration
Corticosteroids INHIBIT capillary budding, fibroblast proliferation, epithelialization, and collagen synthesis. Strongly impair healing. Vitamin A may partially counteract effects. Avoid if possible during critical healing period.
NSAIDs May slow healing by inhibiting inflammation (controversy exists) Benefits of analgesia often outweigh risks. Short-term use unlikely to significantly impair healing.
Chemotherapeutics Inhibit cell division and collagen synthesis Delay elective procedures during chemotherapy if possible.
Vitamin E (excess) Slows collagen production Avoid excessive supplementation during healing.
Nutrient Role in Healing Deficiency Effect
Protein Collagen synthesis, immune function, fibroblast proliferation Decreased wound strength, prolonged healing, edema
Glucose Primary energy source for leukocytes and fibroblasts, component of ground substance Impaired collagen formation and wound strength
Vitamin C (Ascorbic Acid) Required for hydroxylation of proline and lysine in collagen synthesis Impaired collagen synthesis, poor wound strength (scurvy)
Vitamin A Epithelialization, collagen synthesis, immune function Impaired epithelialization, increased infection risk. Can counteract steroid effects.
Zinc Epithelial and fibroblast proliferation, enzyme cofactor Delayed epithelialization, weak granulation tissue. EXCESS zinc also impairs healing!
Iron Oxygen transport (hemoglobin), collagen synthesis Anemia, poor tissue oxygenation, impaired collagen formation
Copper Collagen cross-linking, elastin formation Weak collagen, reduced wound strength

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