Open wounds

Question 1

What is the difference between wound contamination and infection?

Answer 1

Contamination is the presence of microbes on the wound surface. Contamination can lead to colonization in which surface microbes are replicating. Colonization can lead to infection in which there is invasion and replication of microbes within the tissue.

Question 2

What are some disadvantages of second intention healing?

Answer 2

Process is inefficient, and resultant epithelium is fragile and easily abraded. Wound contraction may impede normal function.

Question 3

What are some factors that might delay wound healing?

Answer 3

Systemic disease, malnutrition, local tissue hypoxia and ischemia, bacterial colonization, altered cellular and stress response, repetitive trauma, presence of necrotic tissue, and tension.

Question 4

Describe the main differences in open wound healing in the dog and cat?

Answer 4

Open wound healing may be delayed in the cat, with lower amounts of granulation tissue. In one study at 21 days open cat wounds were 34% epithelialized and 84% healed, whereas dog wounds were 89% epithelialized and 98% healed.

Removal of the subcutis reduces wound perfusion, granulation, contraction, epithelialization and total wound healing in open wounds. At 21 days epithelialization with removal of the subcutis was 20% in cats and 61% in dogs.

Question 5

What psi is considered high pressure wound lavage?

Answer 5

Above 5-8 psi

Can achieve this by attaching a 22 gauge needle to a 1L fluid bag and placing the fluid bag under 300 mm Hg.

Question 6

What is the effect of indolent pocket wounds on healing?

Answer 6

Delayed contraction.

Question 7

Describe the different dressing changes available for wound treatment in companion animals

Answer 7

See table page 1414 Tobias

Question 8

What are the different types of wound debridement that can be used during definitive wound care?

Answer 8

En bloc, layered, nonsurgical (enzymatic, nonenzymatic)

Question 9

In cases of bone exposure in open wounds how can vascularity of the wound bed be improved?

Answer 9

Forage of the bone to allow communication of the vascular medullary canal with the wound bed.

Question 10

What are some examples of nonenzymatic nonsurgical debridement materials?

Answer 10

Honey, hypertonic saline, sugar, wet-to-dry bandages, maggots

Question 11

What wounds are enzymatic debridement agents (i.e. collagenases) typically indicated for?

Answer 11

Chronic, indolent, non-healing wounds in which surgical debridement is not possible. They are typically expensive and non-selective.

Question 12

How is honey antibacterial?

Answer 12

Produces low quantities of hydrogen peroxide, acidic pH, hyperosmolar (dehydrate organisms, draw exudate and accompanying debris from the wound), antioxidant content, stimulation of immunity (T and B lymphocytes, phagocytic activity, cytokine release from monocytes)

Question 13

What is the inhibin number of honey?

Answer 13

A measure of the antibacterial properties of the honey (dilution to which the honey will retain its antibacterial activity)

Question 14

The larvae of what fly is used for maggot wound therapy?

Answer 14

Lucilia seratica (will not destroy healthy dermis and subcutaneous tissue. Will destroy healthy epithelium)

Question 15

What are examples of wound dressings that may be appropriate for mildly exudative, moderately and markedly exudative wounds?

Answer 15

Mildly: hydrogels
Moderately: Hydrocolloids or polyurethane foam dressings
Markedly: Alginates

Question 16

What is the benefit of maintaining a moist wound environment?

Answer 16

Enhances autolytic debridement by keeping the cellular and cytokine rich exudate at the wound surface

Question 17

What are some topical antimicrobial agents that can be used on open wounds?

Answer 17

Topical ointment (triple AB therapy: polymixin, neomycin, bacitracin zinc)

Slow release silver dressings (slow release dressings more effective than 1% silver sulfadiazine)

Question 18

Why are silver dressings only recommended in the inflammatory phase of wound healing?

Answer 18

They have been shown to have a toxic effect on human keratinocytes in vitro

Question 19

What organisms are silver-impregnated dressings effective against?

Answer 19

Wide range of aerobic and anaerobic bacteria, yeasts and filamentous fungi.

Also reduce concentrations of inflammatory cytokines (TNF-alpha, IL-8).

Question 20

What effect are bioscaffolds and synthetic matrixes supposed to have on wound healing?

Answer 20

Stimulation of matrix deposition, angiogenesis and epithelialization. Seem to have more of an effect on chronic wounds in inhibiting the actions of MMPs - shifting the balance toward proliferation rather than degradation of the extracellular matrix.

Question 21

What is the effect of chitosan on wound healing?

Answer 21

Increases granulation tissue formation through upregulation of growth factors (TGF-B, PDGF, fibroblast production of IL-8).

Question 22

What pressure is generally recommended for NPWT in dogs?

Answer 22

-80 to -125 mmHg (lower for grafts -60 to -75)

Question 23

What are the reported effects of NPWT on the wound bed?

Answer 23

Improved wound perfusion (local reductions in PCO2 and increased PO2), reduced edema, stimulation of granulation tissue formation, decreased bacterial colonization, removal of exudate from the wound.

Question 24

Do high pressures of -400 mm Hg lead to increased or decreased wound perfusion with NPWT?

Answer 24

Decreased. Very high pressures associated with reduced perfusion. Pressure of -125 mmHg is generally recommended and macrodeformations in the wound bed may stimulate release of VEGF.

Question 25

What pressures are recommended for negative pressure wound therapy?
What about for over skin grafts?

Answer 25

-80 mmHg for gauze based systems, and -125 mmHg for foam based systems.
-65 to -75 mmHg is recommended for over skin grafts.

Question 26

What are the proposed benefits of negative pressure wound therapy over skin grafts?

Answer 26

Stabilization of the graft, reduced fluid accumulation under the graft, prevention of dessication and microbial contamination of the graft.

Question 27

According to Hamil 2020 in Vet Surg were the results of pretreatment wound cultures from open traumatic wounds predictive of subsequent wound infection?

Answer 27

No - there was no correlation between the results of initial wound cultures and the subsequent development of wound infection. Bacterial species cultured at the initial wound swab also did not correlate with those subsequently cultured from infected tissues.

Question 28

For cats with bite wounds what were 5 factors associated with an increased risk of mortality in a study by Tinsely 2023 in JAVMA?

Answer 28

Increasing age, decreased body weight, not undergoing surgery, increased animal trauma triage score, decreased modified Glasgow coma scale.