Small Animal Wounds - Initial Approach

Again, describe the inflammation phase of wound healing…

In the first 48hrs -

• Platelet plug formation

• Cytokines release from damaged tissue cells → inflammatory response

• Initial vasoconstriction → vasodilation

  • Increased blood flow and vascular permeability at the wound

• WBCs (mainly neutrophils and macrophages) migrate into the wound

  • Attack bacteria, remove damaged tissue and foreign material

Describe the proliferative phase of wound healing…

2-5 days -

• Fibroblasts and capillaries migrate into the wound

  • Creates framework for other cells to grow on

• For a surgical wound:

  • Epithelial cells cover wound within 48hrs

• For open wound:

  • Granulation tissue fills wound

  • Acts as scaffolding for migrating epithelial cells

Describe the maturation and remodelling phase of wound healing?

Takes MONTHS to a year

• New collagen fibers organise along lines of tension

• Scar then CONTRACTS, closing in the wound on the edges

** scar is 20% weaker than normal tissue

What are the two main factors that can affect wound healing? Think of some examples of each…

Local

• Perfusion, infection (causes prolonged inflammatory phase), tension and movement at the wound

• Foreign material and fluid accumulation can also prolong inflammatory phase, acting as sites for infection

Systemic

• Stuff like age, current medications, and nutrition can slow wound healing

  • Steroids → inhibit inflamm. response, prolonging it

• Neoplasia and metabolic diseases can do the same

What are the different types of wounds you could have categorized by cleanliness? How does this affect your approach to treatment?

Categorized by:

• Clean - treated via primary closure

• Clean contaminated - can be treated via primary closure in some cases; other cases, delayed primary closure is best

• Contaminated - best treated via secondary closure; provide open wound management first day, then closure 5-10 days later

• Dirty - SECOND INTENTION healing best for these kinds of wounds

Describe the different methods for wound closure… (hint: 4)

Primary Closure:

• Immediate closure of healthy viable tissue without tension

• Good for surgical wounds, some traumatic wounds

Delayed Primary Closure:

• Used for wounds with minimal contamination, questionable viability, or tension

• Close defore granulatoin tissue starts but after bacteria and foreign material has been removed

• Manage as an open wound initially, then close by days 2-5

Secondary Closure:

• Closure once GRANULATION TISSUE has been formed

• Good for contaminated wounds

• Open wound management then closure at days 5-10 when healthy granulation tissue is present

Second Intention Healing:

• Essentially, wound is left to heal on its own

• Reserved for dirty and infected wounds, or large skin deficits that cannot be closed

What are the Halstead Principles for closure of a simple, surgical wound?

1) Gentle tissue handling

2) Accurate hemostasis

3) Preservation of local blood supply

4) Aseptic technique

5) Close tissues without tension

6) Careful approximation of tissues

7) Ensure no dead space

How do you perform open wound management?

Aim to provide optimal conditions for wound healing or prepare the wound for delayed closure… may require anesthetics, multiple dressings, and may take long. Prepare the owner for the timeline and the price

Once the patient is stable, you will want to:

• Identify and control any infection

• Remove debris and necrotic tissue

• Prevent further contamination and damage to the wound

First:

• Cover wound with sterile dressing or pack with sterile K-Y jelly, then clip a wide margin of fur around the wound

Then lavage

Then debride

Then dress

How would you lavage a wound and why?

• Reduces bacterial contamination, removes foreign material, and rehydrates necrotic tissue

  • Use saline or LRS

• Use a high volume; attach a giving set w/ a 3 way tap, attached to a 20-30mL syringe and 19g needle

  • Will generate enough pressure to remove debris, but not enough to drive bacteria into deeper tissues

How would you go about debriding a wound?

Surgically or non-surgically

Surgical:

• Remove devitalized or contaminated tissue

• Use sharp dissection with a scalpel OR

  • Scrape with blade

  • Rub with dry swab

Non-surgical:

• Used to remove debris that cannot be removed by lavage or surgical means

• Uses DRESSINGS to debride the wound

  • Moisture dilutes exudate and draws it out, hydrating necrotic tissue. Material loosens and dries into the dressing, which is then removes

• Can also cause injury to normal tissue

What are the three different layers of bandaging?

• Primary or contact layer - can be adherent or non-adherent

  • This controls the wound environment

    • Debrides infected or necrotic tissue

    • Absorbs exudate

    • Protects the wound and promotes healing

    • Can provide analgesia

• Secondary layer

  • Absorbs excess fluid, holds primary layer in place and provides structure to bandage

• Tertiary layer

  • Outer layer secures dressing in place and protects the secondary layer

What are the different kinds of adherent contact layers of bandaging, and what are they most commonly used for?

USED IN THE INITIAL STAGES OF WOUND MANAGEMENT ONLY

• Used to DEBRIDE the wound

• Should only be used initially and the dressing be changed every 24 hours

• Includes “wet to dry” dressings and “dry to dry” dressings

  • Dry to dry self explanatory -

“Wet to Dry” dressings -

• Sterile woven swabs, soaked in hartmann’s / sterile saline and squeezed dry, are placed over the wound

  • Followed by dry sterile swabs

• Fluid, exudate, and material is wicked from the contact layer as the swabs dry

  • Swab then adheres to the wound, and when removed for dressing change, layer of nastiness is stripped

  • Can also damage healthy tissue

• IS PAINFUL!!! Should be done under sedation

• Wound is then lavaged and redressed

  • Change to non-adherent dressings when all necrotic tissue is removed and granulation tissue begins to form

What is the goal of non-adherent dressings? What are the two main different kinds you could use?

AIM: To promote granulation and epithelialization of the wound

• Provites a moist wound environment

• Doesn’t cause trauma to the surface of the wound

Types of non-adherent dressings:

• Foam dressing

  • Absorbent

  • Provides a semi-permeable membrane to allow O2 exchange and controlled evaporation

  • Keeps wound moist but not wet

• Hydrogels

  • Maintain moisture; donate and traps water to absorb wound exudate and rehydrate wound

  • Encourages natural debridement and sloughing

  • Good for dry wounds

** Hydrogels can be used WITH foam dressings for debridement; painless to remove, so may be useful for an animal where repeated sedation isn’t the best

• Change every 24-72hrs

• Lavage out at each dressing change

What does healthy granulation tissue look like?

• Red

• Uniform and flat

• Progressing with each bandage change

• Minimal exudate

What does NON-healthy granulation tissue look like?

• Pale

• Not-progressing

• Usually due to necrotic debris or infection

What is the purpose of the secondary layer of the dressing?

Holds the contact layer in place

• Absorbs exudate that passes through contact layer

• Supports and protects the wound; provides padding

Examples: Soffban, cotton wool, conforming gauze bandage

What is the purpose of the tertiary layer of the dressing?

Holds the intermediate layer in place

• Protects the other layers from trauma and contamination

• Care with elastic self-adherent dressings; may become too tight

When should you use antibiotics for wound healing?

Is indicated in most traumatic wounds; should be used in conjunction with lavage and debridement of open wounds

• If its a non-healing wound, culture it AFTER lavage

• Do not give an open ended course, give a therapeutic course then reassess

What are two different topical wound treatments you could use, and what are their properties?

Silver dressings

• Antiseptic and antibacterial

• In the presence of exudate, silver ionizes to release active silver ions

Manuka honey

• Antibacterial and anti-inflammatory

• High osmotic potential DEBRIDES the wound and draws out exudate

• Promotes rapid formulation of granulation tissue

What is one major thing that could delay wound healing if it gets contaminated? What would you do to combat this?

If the wound gets contaminated at ALL:

• BACTERIAL BIOFILM CAN BE PRODUCED

THIS IS WHY YOU LAVAGE SO OFTEN

• Products are available that disrupt biofilm when using would gels

  • PHMB / betaine (prontosan)

    • Betaine disrupts biofilm

    • PHMB kills bacteria

How do cats differ in their wound healing from dogs?

Have a different cutaneous vascular supply to dogs, therefore, heal more slowly

• Granulation tissue is slower to appear and takes longer to totally cover the wound

• Loss of the subcutis retards wound healing to a greater degree in the cat than in the dog