Abstract

Aquatic animal wounds are challenging to manage by the nature of the environment in which they live. Large open wounds are not conducive to bandaging and apposition of wound edges is often impossible. A xenograft, such as BioSIST™, provides an extracellular matrix in areas that are devoid of the natural scaffolding that is required for normal healing. This paper discusses how to use this product in a wet environment and cites examples of successful outcomes.

Introduction

BioSIST™ is a nonreactive extracellular matrix produced from the swine small intestine submucosa (SIS) (Vet BioSIST™, Global Veterinary Products, Inc., New Buffalo, MI). The matrix contains essential collagens and growth factors, as well as the framework required for cell migration during wound healing. SIS has been used in small animal wound management for several years with numerous citations; its use in non-domestic species, however, is focused on laboratory animals used for assessment of human surgical procedures.⁴ A few reports are available on its use in birds and, in one case, a reptile, but no reports of it use on aquatic animals were found through the authors’ literature searches.^1,2,4,5

Application/Technique

Fish

Piscine skin has incredible and novel healing mechanisms. Recently, an excellent review on fish wound healing and management has become available and should be consulted.³ Some large wounds are beyond the normal healing capacity of the animal. These lesions present a critical situation as fish rely heavily on intact skin to maintain osmotic balance. In these cases, SIS provides an excellent medium for providing a barrier against osmotic loss and for laying down tracks for cells to migrate.

SIS has a short half-life in water. In the authors’ experience, within four days most of the SIS has disintegrated except at suture sites. This may require reapplication, the need to use smaller pieces tacked down over the entirety of the wound, or the placement of secondary barrier material over the SIS. Barriers can include Tegaderm™ (3M Center, Saint Paul, MN) or BioDres® (DVM Pharmaceuticals, Miami, FL). All these methods have been used successfully but, due to the variable nature of each wound, it is difficult to recommend a single way to use SIS.

General Recommendations

Maintain the animal out of water while flowing water over the gills (for general anesthesia principles, see other texts). Debride wounds well. Teleost epidermis is not vascularized; therefore, bleeding is not a good indicator of exposing healthy tissue, rather, tissue texture must be used to assess viability.³ Cut and place the dry sheet of BioSIST™ over the wound. Use simple interrupted sutures to tack the edges of the material around the wound, then randomly place stay sutures in the center of the cut piece of SIS.

Note: When opting to use secondary barrier material as mentioned above, it should be placed and tacked down simultaneously with the SIS. If BioDres® is chosen as a secondary barrier, sutures should be tied loosely since the BioDres® material imbibes water and expands several millimeters. The authors have tied the tacking sutures over a hemostat in order to allow room for the expansion. Tight sutures will constrict (it imbibes with water) the BioDres® material and it will fall off.

Select Cases

1.  An adult, 383 g blackspot puffer (Arothron nigropunctatus) with a 5 cm white, raised wound on the peduncle. Examination of the wound revealed extensive necrosis over 30% of the lateral body wall and exposure of muscle. Mucous smears were negative for infectious organisms and previous aggression in the enclosure suggested bite-related trauma. SIS was tacked in place over the entirety of the wound with numerous stay sutures in the center. The animal was treated with antibiotic and fluid-injected foods for several days. Handling was minimized to avoid disruption of the product. Within days the SIS sheet was disrupted but numerous fragments were attached to each suture site. Early epithelialization was noticeable. By the second week, normal pigmentation, including markings became obvious; examination after immobilization revealed apparently normal tissue.

2.  An adult, 1.6 kg laced moray eel (Gymnothorax favagineus) with conspecific trauma to the mandible.⁵ Examination of the wound revealed a symphyseal fracture and 2 cm of tissue loss on the mandible resulting in exposure of the bone. SIS with an overlay of Tegaderm™ was sutured into available tissue; the fracture was stabilized with suture material. At week one there was a thin layer of granulation tissue over the bone. Closer examination revealed that the Tegaderm™ was in place but only remnants of SIS were still present. At week three there was a thick granulation bed present. At two months, the animal had one section of “scar” tissue, while the surrounding tissue was pigmented with normal markings.

3.  A juvenile, 1.3 kg forktail lates (Lates microlepis) with a descemetocele. SIS was sutured over the descemetocele with fine suture material. Gentamycin and flurbiprofen drops were placed on the eye once daily. The SIS material was unfortunately dislodged during capture at day two, but there was sufficient healing for the corneal epithelium to have sealed the perforation. Keratotomy was performed one week later because there was significant defect present. Currently, the animal exhibits minor corneal scarring. This outcome was extremely successful because without intervention corneal lesions can become advanced and can result in complete perforation and loss of the eye. In other fish, minor corneal perforations and descemetoceles have also been successfully treated using SIS, provided that the lesions were not progressive or extensive.

4.  A 17-year, 55 kg Queensland grouper (Epinephelus lanceolatus) with a surgical excision of a neoplasm. The surgery resulted in a significant defect in the forehead exposing 20×10 cm of muscle. A 70×100 mm sheet of SIS was tacked into place over the entire wound, which exposed muscle fascia. Granulation tissue was observed within the first week over at least 50% of the wound, mostly at the periphery. The following week the entire wound was covered. Over the course of several weeks, these layers thickened and ultimately, pigmented tissue was laid down over the entire site.

Aquatic Turtles: Shell Lesions

In most shell lesions, long-term bandaging techniques (as with epoxy) are frequently employed. By placing SIS in freshly debrided lesions, moistening with sterile saline, and then sealing either with epoxy or bone wax (Ethicon, Johnson and Johnson, Somerville, NJ), defects seem to heal several weeks sooner than animals where the product was not utilized.

Select Cases

Ten juvenile red-bellied short-necked turtles (Emydura subglobosa) developed significant bacterial shell abscesses secondary to overcrowding and lack of basking. These lesions resulted in large defects often extending to the coelomic membrane. Defects in four turtles affected 30–40% of the plastron, smaller abscesses were found in the carapace. The lesions were managed medically until the infectious process seemed to be resolved. After light debriding, SIS was used as described above followed by an epoxy ‘bandage’. Animals undergoing this procedure had calcification within two months after treatment. It is possible that healing occurred more rapidly, but the epoxy was not removed until a scheduled two-month evaluation.

Aquatic Birds

The product has been used on a penguin with pododermatitis at the Aquarium. Surgery was performed on the animal’s plantar surface. The SIS was placed deep within a debrided area and sealed over by apposing surgical edges. The animal recovered well in a dry enclosure and has had no recurrence of pododermatitis lesions.

Successful use of SIS in aquatic animals is contingent on the following:

• Appropriate preparation of wounds
• Resolution of any infectious or inflammatory process
• Avoiding disruption of the SIS while tacked onto lesion (as with nets or handling)
• Under some circumstances, a second covering may prolong contact and decrease disintegration rate (note that these may become foreign bodies if they fall off)
• Reapplication may be necessary
• Close attention to the osmoregulatory status of teleosts is needed

Summary

All of the described cases are highly subjective based on the authors’ observations. Most lesions had an incredible expanse or severity that was not, in the authors’ opinion, conducive to healing. In these cases, the author felt BioSIST™ was extremely important for the full recovery of these animals. To further document the effectiveness of BioSIST™ in aquatic animals, a future direction will include a controlled study examining wound healing with and without the product.

Literature Cited

1.  Chitty JR. Use of VetBioSIST™ in Bumblefoot Management. In: AAV Proceedings. August 26-30, 2002; Monterey, CA.

2.  Divers S. Use of VetBioSIST skin grafting techniques in reptiles. Exotic DVM. 2000;2.3:62–63.

3.  Fontenot DK, Neiffer DL, Ed Wilson GH. Wound management in teleost fish: biology of the healing process, evaluation, and treatment. Vet Clin Exot Anim. 2004;1:57–86.

4.  Hernandez-Divers SJ, Hernandez-Divers SM. Xenogeneic grafts using porcine small intestinal submucosa in the repair of skin defects in four birds. J Avian Med Surg. 2004;17(4):224–234.

5.  Stroud PK, Amalsadvala T, Swaim SF. J Avian Med Surg. 2003;17(2):78–85.