In general, reptiles undergo the same healing processes as mammals with the four healing stages of inflammation, debridement, repair, and maturation. However there are some unique aspects of reptile physiology that make wound treatment in reptiles unique. These include:
Metabolic rate, and therefore healing rate, that is affected by environmental temperature11
Behavioral fever as a mechanism of immune modulation11
Heterophils (versus neutrophils): heterophils produce a solid type of exudate11
Heterophils (versus macrophages) as the most persistent white cell in the wound, which can lead to prolonged exudate formation11
As wounds heal, the tissues exhibit different wound stages. The best therapy for the wound depends on the stage of the wound. Therefore, treatment should be tailored to the wound over time to best promote rapid healing. This discussion reviews appropriate therapies for treatment of wounds in reptiles including tailoring care to the stage of wound healing.
Due to the longer healing time in reptile wounds, the window for potential infection is longer. Therefore, systemic antibiotic therapy may be appropriate for even minor wounds. Therapies of choice for reptiles include:
Relatively healthy, uninfected wound: Ceftazidime 20 mg/kg IM q48–72h5
Very contaminated wounds: Penicillin benzathine 20,000 IU/kg SC q48h5 plus amikacin 5 mg/kg SC then 2.5 mg/kg SC q72h.5 Always ensure patients are hydrated before administering amikacin to reduce the risk of nephrotoxicity.5 The author administers amikacin in a pocket of SC fluids.
Oral antibiotics for very contaminated wounds: Enrofloxacin 5 mg/kg PO q24h5 (avoid injections since tissue necrosis is common in reptiles) plus metronidazole 20 mg/kg PO q48h x 7 doses5
Antifungals: Itraconazole 5 mg/kg PO q24h5
In general, reptiles have a predominance of mu opioid receptors, so mu agonists are currently considered most appropriate for analgesia. Hydromorphone at 0.1–0.5 mg/kg SC q24h,8 tramadol at 5 mg/kg PO 72–120h1 or at a reduced frequency if drowsiness or constipation occur. Remember to administer local blocks prior to debridement or surgery, such as lidocaine at no more than 5 mg/kg total dosage.5
Wounds are often a source of fluid loss via exudates or hemorrhage. For a maintenance dosage of fluids, 15–40 mL/kg/day5 may be used, administered subcutaneously, intracoelomically, or intravenously. Soaks in warm water may aid in maintaining patient hydration. As an added benefit, many patients will drink when soaked, and many will be stimulated to defecate, which seems to help promote gastrointestinal motility.
The patient should be provided a temperature gradient that encompasses the preferred optimal temperature zone. This allows the patient to follow its own physiological drive to regulate body temperature. Always provide a warm spot at the upper end of the species preferred optimal temperature zone to allow the patient to generate a behavioral fever.11 Basking lights are best since hot rocks and floor heat often have inconsistent temperatures (hot spots) and can lead to thermal burns over time. Temperature guns are handy for daily monitoring of hot spots, cool spots, and patient temperature.
Proper nutrition is important to support physiologic demands for healing. Getting a patient to eat may entail managing stomatitis. Give electrolytes and fluids first and ensure the GI tract is not static. Oxbow herbivore fine grind and carnivore formulas are effective for many reptiles. Start with a volume of formula of 5–20 mL/kg q48–72h.5 Fluids may also be given orally on the days when formula is not administered. Consider placing an esophagostomy tube, particularly in chelonians, where administration of oral medications or nutritional supplements may be difficult.
Therapies for Stage One: The Inflammatory Stage
This stage occurs at 6–24 hours of wound age (similar to mammals6,11) and is characterized by vasoconstriction and other hemostasis mechanisms, followed by vasodilation to permit inflammatory mediators to initiate the inflammatory cascade. Treatment of wounds in this phase should focus on promoting hemostasis, reducing wound contamination, and, if primary closure is selected, preparing the wound for closure. Therapies should include:
Wound flushing: Copious amounts of saline, or, in very contaminated wounds, a very dilute chlorhexidene (< 1% concentration) may be used. Reports of reptiles exhibiting toxicity after chlorhexidene soaks are mentioned in the current literature.2 Therefore, whole body soaks in chlorhexidene are not recommended by the author.
Primary closure: Be sure not to invert the skin (horizontal mattress is safest). Be aware that absorbable sutures may not always be absorbable in reptiles. Reptile skin often takes longer to heal than mammalian skin, so sutures usually need to be left in place for 6–8 weeks or until after ecdysis (whichever is first).7
OR Secondary closure: Wet-to-dry bandages - gauze moistened with sterile saline, dry gauze, securing layer such as elasticon, vet wrap, or tegaderm.9
Therapies for Stage Two: The Debridement Stage
This stage starts at 6–12 hours of wound age and lasts several days or longer in severely contaminated wounds. It begins with the appearance of white blood cells in the wound. In reptiles, these are heterophils and macrophages, which remove necrotic tissue, bacteria, and foreign material. They also release substances to stimulate fibroplasia, collagen synthesis, and angiogenesis. Wounds in this phase are characterized by exudates, many white blood cells, and necrotic tissue.6,9,11 It is important to note some unique physiology of reptiles at this stage:
Reptile heterophils do not produce the liquefied or creamy suppurative exudates that mammalian neutrophils produce. This is due to a lack of heterophilic proteases and differences in hydrolytic enzymes. As a result, reptilian heterophils produce solid aggregates or clumps, often with a lamellated appearance, characterized by concentric layers of solid material. This is why reptilian abscesses are usually "solid".11 To resolve chronic infection of wounds in reptiles, this type of exudate must be debrided from the wound with as much of the thick capsule enclosing the wound as possible. Fungal, aerobic bacterial, and anaerobic bacterial culture of the capsule wall is appropriate to target antimicrobial therapy.
Reptile tissues have a slower metabolic rate, therefore, in the author's experience, necrotic tissue may take longer to declare itself. It is not unusual to see new wound necrosis 10–14 days after the initial wound evaluation.
Diagnostics and therapies for wound presenting in this stage should include:
Wound culture: Fungal culture, bacterial aerobic culture, bacterial anaerobic culture.
Wound biopsy: In chronic wounds, it is important to rule out neoplasia or viral lesions, and may help identify an underlying fungal pathology. Save 1–2 biopsy pieces frozen to use for fungal culture or viral PCR if indicated by histopathology.
Debridement: Repeated debriding of necrotic tissue as it presents or solid exudates may be necessary.
Wound flushing: Initial cleansing flush of saline or very dilute chlorhexidine (no more than 1% concentration), followed by daily flushing with saline.
Bandaging: Wet-to-dry bandages are appropriate for exudative wounds.9 Bandages may be secured with tegaderm, vet-wrap, elasticon, and/or duct tape. More often, reptile tissues have a tendency to dry out than to be too moist. Tie-over bandaging6 may be necessary in snakes or in patients with wounds in unusual locations. Non-absorbable suture is used to place cutaneous suture loops adjacent to the wound margins. Umbilical tape can then be laced through the loops (like a shoe-string) and used to stabilize bandaging placed over the wound.
Topical antibiotics or antifungals: Mix silvadene 50/50 with ilex diaper rash cream and apply in a thin layer to the wound, then cover with a telfa and secure with tegaderm or other adhesive (elasticon, vet wrap, etc). This will treat infection while protecting the wound from environmental contamination and desiccation. Effective topical antifungals include nystatin cream and terbinafine cream applied in a thin layer. Medihoney may also be used, but be aware that this can attract ants in patients housed outdoors. Also, acticoat dressing is helpful to reduce bacterial infection in wounds. I recommend moistening the acticoat with sterile saline before application to reduce wound desiccation.
Therapies for Stage Three: The Repair Stage
This stage starts at 3–7 days of wound age and is characterized by the presence of fibroblast proliferation and capillary infiltration to the wound.6,9,11 The fibroblasts in reptiles originate from the lateral wound margins (rather than the ventral subcutaneous tissues as in mammals), so length of this stage is affected by the diameter of the wound.9 A significant epithelial scab may overlay the healthy granulation tissue. This scab usually does not require frequent debridement, but occasional debridement may be needed if it continually becomes thicker. Healthy granulation tissue is red, resistant to infection, and considered to be non-painful. Re-epithelialization occurs over the healthy granulation tissue from the wound margins.
Therapies appropriate for this stage:
Routine wound flushing: Sterile saline or half-strength Dakin's solution. Dakin's solution is effective as a wound flush to help remove necrotic tissue and effective as an antimicrobial.
Hydrogel dressings: Biodress, Duoderm, and sterile gauze moistened with sterile saline all help to create a sterile and moist wound environment. Keeping the wound moist reduces the formation of eschars, which impede wound healing.
Topicals as needed for infection: Some ointments have been shown to slow healing since the cream base is hyperosmolar and can induce formation of a neo-eschar. Use as needed to treat infection, but otherwise focus on maintaining a sterile field of healthy, moist granulation tissue.
REGRANEX® Gel (becaplermin) has biological activity similar to that of endogenous platelet-derived growth factor, which includes promoting the chemotactic recruitment and proliferation of cells involved in wound repair and enhancing the formation of granulation tissue.4 Mild bleeding at the site is important for effectiveness since it works by chemotactic recruitment. A contact time of at least 2 minutes is important for effectiveness. Apply in a 1/16th inch thick layer over the wound, then cover with a sterile moist dressing. Keep the ointment refrigerated. This treatment is contraindicated in neoplastic conditions.10
Vacuum-assisted wound closure3 may be started at this stage. It is important that hemostasis be achieved, to avoid exsanguination of the patient via vacuum. It is therefore not recommended to start this therapy until the wound is 3–5 days old and apply the vac only in areas without significant open vasculature (for instance, a traumatic amputation site that still has vessels that easily bleed when disturbed would be contraindicated).
Therapies for Stage Four: The Maturation Stage
This stage is characterized by a closed wound with ongoing remodeling of wound tissues and strengthening of wound integrity. During this time significant wound contracture may occur. Physical therapy with routine stretching of the wound is helpful during this stage to prevent the wound from inhibiting patient movement. Surgical treatment may be needed during the course of treatment to relieve wound tension.
The most important component of wound healing in reptiles is dedication of animal owners or animal care staff. Reptile healing is a lengthy process that may take months or even years in some cases. In the author's experience, having a frank discussion at the initial case evaluation about the expected healing time and potential complications is important to ensure that animal care staff has an understanding of realistic timelines for reptile patients. In addition, routine recheck exams help to ensure the reptile remains on the path of progress. With dedication, reptile wound management often results in rewarding clinical outcomes.
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10. Regranex® gel 0.01% (becaplermin) prescribing information. 2011. OMJ Pharmaceuticals, Inc. San German, Puerto Rico. www.regranex.com/pdf/PI_Full_Version.pdf. Accessed 12 September 2013. (VIN editor: Link updated Dec 17, 2013)
11. Stacy, B. A., and A. P. Pessier. 2007. Host response to infectious agents and identification of pathogens in tissue section. In: Jacobson, E. R. (ed.). Infectious Diseases and Pathology of Reptiles. CRC Press, Boca Raton, Florida. Pp. 257–297.