Wounds and Wound Care Lesson
After completing this unit the student should be able to:
In this unit, we will be reviewing concepts about wounds and basic wound care. The veterinary technician plays an integral role in wound care, not only at the time the animal is first presented, but also throughout the healing process. The technician is also often expected to provide client education regarding wound management.
Click on the photos to see an enlargement of the images.
Sutures and bandages are covered in a separate section.
McCurnin D and Bassert J: Clinical Textbook for Veterinary Technicians 6th edition, Chapter 4, pp. 1230-1235, 1243-1250, and 1001.
Writing assignment is at the end of the lesson.
Stages of Healing- The stages of healing occur sequentially but may overlap in time. Healing may also occur at different rates in various regions of the same wound. The stages of healing are the inflammatory, debridement, repair, and maturation phases:
Granulation tissue fills the wound defect and enables epithelialization. New epithelium can be seen initially along the edge of the wound as a white or light pink smooth border:
Although we like to see granulation tissue, many owners are very disturbed by its appearance. Healthy granulation tissue is red and shiny and bleeds easily, but it is not painful and infection is unlikely to occur. However, to a lay person, granulation tissue looks like something bloody and slimy that is seen on a monster in a horror movie. Therefore, many technicians prefer to change a bandage out of the owner’s sight until they are sure that the owner knows what to expect. Technicians often have the role of comforting the owner while explaining the optimistic meaning of granulation tissue and showing the owner where the epithelium or "new skin" is forming along the edge.
Wound strength (Figure 4-1 in McCurnin)
How long after surgery are sutures removed from veterinary patients?
What degree of wound strength do you think the wound has developed by the time the sutures are removed?
And does this mean the animal has enough wound strength to resume normal activities?
Classification of wounds
Wound care is dictated by the condition of the tissue at the time of presentation. The major classifications of wounds are clean, clean/contaminated, and infected.
Types of wounds- The cause of a wound is also a factor in the choice of specific wound treatments. The most common types of wounds animals experience are
Types of healing
All wounds, regardless of cause or tissue conditions, go through the same basic phases of healing. If closure via suturing can be done, this will enhance wound healing and lessen the size of the scar, but not all wounds can or should be closed on presentation.
During many injuries, surrounding tissue is also damaged, compromising the blood supply. If there is devitalization and necrosis of tissue, surgical repair is more challenging with likely complications. Often treatment may be performed in stages, or delayed to reduce contamination and infection. Delaying closure allows time for devitalized tissue to become obvious in appearance so surgical debridement is more effective. Sometimes there is so much tissue missing that surgical reconstruction is not an option, and long term wound management is required.
The term "healing by first or second intention" are actually categories of wound closures:
Factors in wound healing-
Factors that influence wound healing include characteristics of both the wound and the host, or animal.
Wound factors that delay healing are:
Host factors that contribute to delayed healing are:
The goals of wound care are to prevent contamination and protect the tissues. The treatment emphasis will change depending on the phase of healing that is present and the conditions of the tissues and patient.
Drains are commonly made of flexible nonabsorbable tubing, and placed in a wound to:
One or two openings at or near the wound site is maintained for the placement of the drain into deeper tissues. The drain is sutured in place where it emerges at these openings. Often gentle lavage is performed at the drain sites.
There are two main types of drains: passive and active. Passive drains accomplish drainage by gravity.
Active drains accomplish drainage by some sort of aspiration. The part of the drain that resides in the wound is fenestrated, so that fluid is collected from throughout the wound space. The drain is attached to a device such as a syringe or a Vacutainer-type tube which collects the fluid from the site through the drain. Commercially prepared closed suction devices are also available.
Removal of drains
Drain removal is often done by the technician. Drains are usually not left in a wound for any longer than 4 days because granulation tissue may start to form around the drain by 5 days. If left in too long, the body may heal around the drain and form a fistulous tract.
In this scenario, the drain is under a suture line and exits at two points on either side of the suture line.There are anchor sutures at each end. The steps for correct removal of a drain are demonstrated in the following mock set up:
Although it is a quick procedure, drain removal sometimes appears to be uncomfortable for the animal, so take appropriate precautions.
Dressings are medications or materials that are applied directly to a wound in order to enhance healing. They are often part of the primary layer of the bandage. The type of dressing used will vary depending on the phase of healing and the objective of the wound treatment. Hydrotherapy, or wound lavage with water or isotonic fluids is often done before applying a new dressing and bandage to an open wound.
The following problems indicate that complications have occurred and the veterinarian should be notified so that treatment can be modified.
Dehiscence- The wound repair breaks down and the wound becomes open again. If there is swelling around the sutures, sometimes the suture will actually cut through the tissue as it swells, weakening the repair. Sometimes dehiscence can be prevented if problems with the incision site are addressed early.
Websites of interest
Maggot debridement therapy- Have you ever seen an animal infested with maggots? It is not a pretty sight! Here is a website about maggot debridement therapy- information on what have been termed the "world’s smallest surgeons" and how they are purposely cultivated and used for wound debridement. Note that there are important differences between different types of maggots- some can be beneficial and some are not.
Leech therapy- information on the resurgence of using leeches in wound therapy with venous congestions and skin grafts:
World Wide Wounds- lots of information on wounds and wound care
Matthews KA and Binnington AG: "Wound Management Using Honey" The Compendium on continuing Education for the Practicing Veterinarian:Small Animal January 2002 volume 24(1):53-60
Matthews DA and Binnington AG: "Wound Management Using Sugar" The Compendium on continuing Education for the Practicing Veterinarian:Small Animal January 2002 volume 24(1):53-60
McCurnin D and Bassert J: Clinical Textbook for Veterinary Technicians 5th edition WB Saunders, Philadelphia, 2002, pp. 102-106, 114-116, 600-01
Swaim SF and Gillette RL: "An Update on Wound medications and Dressings" The Compendium on Continuing Education for the Practicing Veterinarian:Small Animal October 1998 volume 20(10):1133-1145
Swaim SF, Hinkle SH, and Bradley DM: "Wound Contraction: Basic and Clinical Factors" The Compendium on Continuing Education for the Practicing Veterinarian:Small Animal January 2001 volume 23(1):20-34
Wilson, D: "Wound Management" Veterinary Technology presentation, Northern Virginia Community College, Sterling, Virginia, 2003.
Wormack BH: "Wound Management: Treatment & Patient Care" Veterinary Technician November 2001 volume 22(11):599-605
Acknowledgement: Many thanks to the doctors and staff of Alexandria Animal Hospital for wound photo contributions.
When you have completed your study of the lesson, please answer the following questions and submit your answers via e-mail. You may answer the questions directly in an e-mail or you may download the Word file, fill in your answers and return the Word file as an attachment.
Send to Dr. Bidwell: firstname.lastname@example.org
Some students have reported having difficulty finding answers to the following questions - 5, 14, 15 and 26. If you can't find those answers please leave them blank and those answers will be provided.
1. What happens to a wound during the inflammatory phase?
2. What happens to a wound during the debridement phase?
3. What happens to a wound during the repair phase?
4. What happens to a wound during the maturation phase?
5. What roles do growth factors serve in wound healing and where do they come from?
6. Describe the appearance of poor quality granulation tissue.
7. Why would a topical corticosteroid ointment be contraindicated for a wound dressing?
8. What is "dead space" and how does it form?
9. Name two commonly used materials for surgical wound repair that increase inflammation.
10. Which surgical wound will likely heal in the shortest amount of time--electroscalpel, electrocoagulation, or steel blade?
11. Let’s pretend I have a pet who is getting chemotherapy and radiation treatments for cancer. Explain to me why a simple cut on his foot is taking over a month to heal.
12. What techniques of immediate open wound care are used to prevent the introduction of hair into the wound?
13. What is the "golden period"?
14. Which wound closure method would likely result in the largest scar?
15. Why is an abrasion so painful?
16. What is an avulsion?
17. Explain the difference between first, second, third, and fourth degree burns.
18. Name two iatrogenic causes of burns in the animal hospital setting.
19. What is "strike through"?
20. Why are drains often placed for the repair of puncture wounds?
21. Devitalized tissue, especially that of degloving injuries, may take up to how long to undergo recognizable changes?
22. What are decubitus ulcers?
23. Explain why decubitus ulcers are difficult to heal.
24. What is "proud flesh" and where is it commonly found?
25. Name some methods of controlling proud flesh.
26. What vaccination is often given to horses at the time of initial wound treatment?
27. Name two types of agents that should not be used in lavage fluids.
28. What are some devices that can be used for wound lavage technique?
29. What is the difference between active and passive drains?
30. What is the difference between primary closure, delayed primary closure and secondary closure?
31. When is granulation tissue usually seen (ie, how many days after the initial wound?)
Answers to wound strength questions
On average, most sutures are removed around 10 days post op. Looking at figure 4-1 this would mean that the wound strength is still fairly low, less than 50%. How do we get away with this and not see more problems post op? Take into account that with a surgical wound that is sutured, the time frames for the early healing phases are markedly decreased because the skin edges are apposed and there is very little defect to fill. Epithelialization of a sutured incision can occur as early as within 48 hours, compared to 4-5 days in an open wound that is not sutured. Therefore, wound strength is developed at a faster rate in a sutured surgical incision and is in the maturation phase at the time of suture removal. While it may support wound strength to leave the sutures in longer than 10 days or so, most technicians find that the longer sutures are present, the more likely the sutures act as foreign bodies, causing an inflammatory reaction that is counterproductive to wound healing and maturation. For common elective surgeries, we often find that many animals resume normal activities on their own before suture removal, but most doctors prefer to restrict activity until the incision is healed and in the maturation phase. Of course, activity recomendations will differ depending on the surgery, especially if rehabilitation is required post op.