Dr. Schmiedt, assistant professor of soft tissue surgery at the University of Georgia Veterinary Teaching Hospital, advises a back-to- basics approach.
"I am something of a Luddite here,” Schmiedt said. "When dealing with hard-to-handle wounds, I think veterinarians should revert to the basics of wound healing. There is always a biological basis for why a wound won’t heal.”
A wound stuck in the inflammatory and debridement stage, for example, is possibly being prevented from moving to the repair phase by dead or necrotic tissue, or an infection, or "some magic treatment one keeps slathering on,” he said.
"If a wound is stuck in the repair phase with a granulation bed that will not contract and epithelialize, this is usually because the tension is too great for the myofibroblasts, there is infection or inappropriate wound care,” Schmiedt said.
"Identifying that biological problem and correcting it is critical. Reverting to the latest device, cream or treatment is not the answer to getting wounds to heal.”
Bryden J. Stanley, BVMS, MACVSc, MVetSc, Dipl. ACVS, an associate professor in the surgery department at the Small Animal Clinical Sciences College of Veterinary Medicine at Michigan State University, also likes to first look at the how’s and why’s behind wounds that just don’t seem to want to heal.
| Laser therapy and wound healing
The latest methods of wound healing hold interest for Bryden J. Stanley, BVMS, MACVSc, MVetSc, Dipl. ACVS, but Stanley and others say they would like to see more research published on the benefits of laser therapy.
"There is quite a bit of interest in the application of low-level laser to modulate wound healing and other biological processes,” said Dr. Stanley, associate professor in the surgery department at the Small Animal Clinical Sciences College of Veterinary Medicine at Michigan State.
"The radiation energy delivered by laser is thought to act at a subcellular level, stimulating mitochondrial production of ATP [adenosine triphosphate], which can then be used for protein and prostaglandin synthesis. Laser as also been shown to stimulate the release of several growth factors that modulate wound healing.”
Stanley noted that the literature on the subject has shown mixed results, something she believes may be due to the widely variable wavelengths in play, as well as differing dosage concentrations, dosing intervals, treatment start times and wound types in the studies.
"We are currently looking at the effects of this modality on wounds in a controlled clinical study, and should have results by the end of the year,” she said.
Chad Schmiedt, DVM, assistant professor of soft tissue surgery at the University of Georgia in Athens, is highly skeptical about the benefits of lasers on wounds.
"The whole laser question is still a conundrum,” he said. "Many veterinarians, including specialists, swear by the analgesic and wound-healing advantages afforded by laser therapy. It is a modality that is heavily marketed by the industry and makes veterinarians a lot of money.”
While there is theoretical evidence that laser therapy may be beneficial, and most of the actual scientific work has been done in non-target species, in veterinary medicine the laser industry relies heavily on "anecdotes and non-controlled studies” to present their case, Schmiedt said.
"They present case study after case study of what often looks like normal wound healing, but, at least in my conversations with people in the industry, they are very resistant to funding controlled clinical trials in our target species,” he said. "The obvious risk is that if they don’t prove healing advantages, they will be out a lot of money, so it’s probably not worth the risk.” Nicole A. Heinrich DVM, Dipl. ACVD, of McKeever Dermatology Clinics Inc. in Eden Prairie, Minn., is also on the fence, waiting for more proof of the effectiveness of lasers before making up her mind.
"I have not used laser therapy to help heal wounds because I need more evidence that it would be beneficial for dermatology patients,” Heinrich said.
Narda G. Robinson, DVM, director of the Center for Comparative and Integrative Medicine at Colorado State University’s Veterinary Teaching Hospital, believes there is enough evidence to counter some of the skepticism.
"Laser provides a low-risk, high-yield modality that not only speeds healing; it also gives clinicians a means by which to treat problems for which conventional medicine comes up short,” she said.
Beyond that, Robinson offered further thoughts on the matter:
"Laser therapy repairs tissue in a number of ways; as a result, it excels at treating many types of wounds. The biology of encouraging regrowth after injury involves a complex sequence of changes, nearly all of which laser supports.1 From inflammation and epithelialization to collagen production, wound contraction, angiogenesis, and more, light therapy creates both local and systemic responses that foster regrowth and re-establishment of a healthier cellular milieu.
"It can also augment the activity of adipose-derived mesenchymal stem cells, enhance their survival and support their secretion of growth factors in the wound bed.2
"For oral surface wounds, laser therapy helps heal stomatitis as well as mucositis and oropharyngeal ulceration associated with radiation therapy for cancer of the head and neck.3
"For burns, laser therapy outperforms ultrasound in the treatment of pain.4 It reduces the number of inflammatory cells drawn to the region while it increases formation.5
"Wounds of diabetic patients typically heal more slowly. Whether in the mouth6 or elsewhere on the body, photobiomodulation facilitates wound closure through cytokine and growth factor release, acceleration of wound resurfacing, and the deposition of granulation tissue.7
"In summary, laser provides a low-risk, high-yield modality that not only speeds healing; it also gives clinicians a means by which to treat problems for which conventional medicine comes up short.”
"Extent of skin loss, extent of soft tissue damage, compromised blood supply, bacterial burden, anatomic site, condition and age of the animal, financial constraints, animal temperament and even logistical difficulties can contribute to a hard-to-heal wound,” Dr. Stanley said.
"I think one of the best ways to approach a hard-to-heal wound is to decide whether it is largely a management issue, a host issue, or a wound issue.”
The most common of those are management issues that can include motion, tension, pressure on the wound, maceration and desiccation, devitalized tissues, presence of an eschar or self-mutilation.
While host issues are not as common, Stanley considers them important to consider because they can compound other problems, such as malnutrition, uremia, endocrinopathy or exogenous steroids, chemotherapy and old age.
Wound issues include irradiation, neoplasia, foreign body, exposed bone, infection, envenomation and poor perfusion, Stanley said.
"If these contributory factors can be recognized and addressed, we can, with patience, get most of these hard-to-heal wounds healed,” she said.
Nicole A. Heinrich, DVM, Dipl. ACVD, of McKeever Dermatology Clinics Inc. in Eden Prairie, Minn., places treatment of the underlying cause of the wound as one of the most important aspects of achieving successful wound resolution in dermatology patients.
"However,” Dr. Heinrich added, "wound healing is frequently complicated by factors such as abnormal immune status, secondary infection, movement, compression and self-traumatization. These factors need to be addressed as well.”
Skin culture and serial skin cytologies are among the tools Heinrich recommends for identifying and monitoring the progress of secondary infections, while the strategies for dealing with secondary infections include daily wound irrigation and cleansing with chlorhexidine, systemic antibiotics, topical products such as silver sulfadiazine, sugar, RediHeal or mupirocin, as well as frequent bandage changes.
"Chlorhexidine is an antiseptic with excellent activity against Gram-positive bacteria,” she said. "It can be cytotoxic at high concentrations, which may or may not be important depending on the individual case.”
Silver sulfadiazine, which has antibacterial properties, promotes wound healing, but sometimes bacteria will proliferate despite its application, Heinrich said.
"Mupirocin has excellent efficacy against staphylococcus bacteria, but it may delay wound healing,” she added. "Sugar can benefit many wounds, because in high concentrations, it reduces edema, promotes granulation tissue and creates a negative environment for both Gram-positive and Gram-negative bacteria.
RediHeal is another of my favorite products for wound healing. It is promotes granulation tissue and also creates a negative environment for bacteria.”
Schmiedt, with University of Georgia, takes varied approaches with different types of wounds.
For wounds like punctures that enter the abdomen or thorax, contamination of those spaces is a significant concern.
"Often in puncture wounds, the lesion on the outside is the tip of the iceberg,” Schmiedt said.
Addressing potential concerns about structures in compound lacerations that include deeper structures like arteries, tendons, nerves and muscles make such wounds more complicated, while anatomic degloving injuries frequently have an orthopedic component, often in which a joint has been made unstable because of ligamentous damage, he said.
High Tech Approach
Stanley likes to at least consider at all approaches, including negative pressure wound therapy, which has been shown to enhance healing in many situations in veterinary medicine.
"Another therapy that needs to be assessed is topical oxygen and hyperbaric oxygen,” Stanley said.
"Elemental oxygen is crucial to many stages of wound healing, from the oxidative burst of neutrophils through to collagen synthesis. We have some limited experience with topical oxygen therapy, and would like to undertake more work in this area.”
Schmiedt sees a great number of large, complicated wounds.
"Because we are a referral hospital, we tend to see large wounds, wounds that don’t heal easily, and complicated wounds,” he said.
"Again, I revert to the basics: What stage is this wound in? What is the biological basis for this wound not healing? What can I do as a surgeon to get this wound healing—debridement, control of infection, skin graft, skin flap?”
Chronic wounds are also frequent among Schmiedt’s cases. His approach is to first biopsy and culture the tissue.
"If this wound is really a tumor, it probably isn’t going to heal on its own,” he said. "Culturing deep tissue, as opposed the surface film, will help identify causative organisms and guide appropriate treatment.”
Michigan State’s Stanley also advises following the basic tenets for approaching a wound: clipping and thorough cleansing of the periwound and wound; meticulous debridement under aseptic conditions; copious moderately pressurized or pulsatile lavage; and appropriate drainage—usually through the primary layer dressing and bandaging.
"These steps can be repeated as necessary, either every day or every few days, depending on the type of dressing, condition of the wound and the stage of wound healing,” Stanley said.
Stanley’s department takes referrals and is also considered a primary care facility, so the wounds she sees during her rounds run the gamut.
"The cases that come through our emergency service are primarily car accidents and bite wounds, although we see some quite spectacular hunting injuries and domestic accidents,” she said. "Our immediate priorities are to assess and stabilize the patient, and prevent further damage by temporarily covering the wound. Hemostasis of the wound may also be required at this stage.
"It is important that we find out the mechanism of injury, and how much energy the wound has received, as well as any other relevant history, comorbidities, current medications.”
Talking to Pet Owners
Because many dermatology conditions require weeks or months to fully heal, Heinrich places client education high on her to-do list.
"Some key education points for my clients are that the wound may heal slowly, it may require weekly—sometimes more frequent—progress checks, and the owner will likely need to perform wound care at home,” she said.
Stanley also emphasizes the importance of pet-owner involvement.
"It is incredibly important to have the owners on board for the journey,” Stanley said. "When I take on a major wound, one of the first things we do is ensure that we sit down with the owner in person—a wound team meeting—and discuss the way forward and what to expect in terms of outcome and cost over the next weeks or months.”
Among the decisions that need to be discussed are whether debridement is needed, whether to perform a reconstructive procedure or allow a wound to heal by second intention, when to stop antibiotics or when to increase the dressing-change interval.
"Owners must be informed about the pros and cons of each option, and play a definitive role in the discussions leading to each final decision,” Stanley said. "It is also critical to maintain frequent contact with the owners while the patient is hospitalized.”
She also advises keeping photo documentation of the wound.
"These photographs can form the basis of many decision-making discussions you have with the owner,” Stanley said. "They are also very useful if you wish to obtain a specialist opinion. In wound care, a picture tells a thousand words.”
REFERENCES FOR SIDEBAR
1. Prindeze NJ, Moffatt LT, and Shupp JW. Mechanisms of action for light therapy: a review of molecular interactions. Exp Biol Med (Maywood). 2012;237:1241. DOI: 10.1258/ebm.2012.01280.
2. Kim H, Choi K, Kweaon O-K, et al. Enhanced wound healing effect of canine adipose-derived mesenchymal stem cells with low-level laser therapy in athymic mice. Journal of Dermatological Science. 2012;68:149-156.
3. Verma SK, Maheshwari S, Singh RK, et al. Laser in dentistry: An innovative tool in modern dental practice. Natil J Maxillofac Surg. 2012;3(2):124-132.
4. Sari Z, Polat MG, Ozgul B, et al. A comparison of three different physiotherapy modalities used in the physiology of burns. J Burn Care Res 2013; June 28. [Epub ahead of print.]
5. Fiorio FB, Albertini R, Leal-Junior EC, et al. Effect of low-level laser therapy on types I and III collagen and inflammatory cells in rats with induced third-degree burns. Lasers Med Sci. 2013; May 16. [Epub ahead of print].
6. Firat ET, Dag A, Gunay A, et al. The effects of low-level laser therapy on palatal mucoperiosteal wound healing and oxidative stress status in experimental diabetic rats. Photomed Laser Surg. 2013;31(7):315-321.
7. Dixit S, Maiya A, Umakanth S, et al. Photobiomodulation of surgical wound dehiscence in a diabetic individual by low-level laser therapy following median sternotomy. Indian J Palliat Care. 2013;19(1):71-75.