Rectus abdominis free muscle flap for reconstruction in nine dogs

OBJECTIVE: To evaluate the clinical use and outcome of a rectus abdominis microvascular free flap for wound closure in dogs. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n=9) with complex extremity or oral wounds. METHODS: Medical records (2002-2006) of dogs that had a rectus abdominis free tissue transfer to close an extremity or oral wound were reviewed. RESULTS: Nine dogs were identified: 5 had distal extremity wounds, 3 had oral palatal defects, and 1 had a large hygroma excised. A rectus abdominis free tissue transfer with a caudal epigastric vascular pedicle was successfully used for management of these wounds. No major complications occurred with the donor site and a good cosmetic and functional outcome occurred in all dogs. CONCLUSION: The rectus abdominis is a versatile muscle that can be used for reconstructing cutaneous and oral defects with repeatable success. CLINICAL RELEVANCE: Free tissue transfer of the rectus abdominis muscle is a clinically useful technique for closure of a variety of difficult soft tissue wounds.     

Investigation and clinical application of a novel axial pattern flap for nasal and facial reconstruction in the dog

OBJECTIVE: To describe the vascular supply to a facial skin flap based at the commissure of the lip in the dog and report on its use in four dogs. STUDY DESIGN: Experimental and prospective clinical study. Animals Five canine cadavers and four client-owned dogs. METHODS: In the cadavers, the ventral aspect of the zygomatic arch, the ventral margin of the caudal mandible and the wing of the atlas were marked as anatomical boundaries of a skin flap that was elevated from the subcutaneous tissues to the level of the medial canthus of the eye. Methylene blue dye and barium sulphate solution were independently infused through a common carotid (three dogs) or facial artery (two dogs) catheter. Distribution of dye throughout the harvested skin was assessed subjectively. After contrast infusion the flap was excised and radiographed. The technique was used to reconstruct large facial or nasal defects in four dogs after tumour or skin lesion excision. RESULTS: Cadaver dissections and contrast studies clearly demonstrated three direct cutaneous arteries, the superior and inferior labial arteries and the angularis oris artery, arborising within the base of the flap. A separate direct cutaneous branch of the angularis oris artery was identified. An arterial plexus was identified within the distal flap, within which this artery communicates with the transverse facial artery and a cutaneous branch of the masseteric artery. Dye infusion caused discolouration of the elevated skin and vasculature within the flap. The flap survived in all clinical cases with marginal distal necrosis in one dog. CONCLUSIONS: The complex facial flap described is perfused by three direct cutaneous arteries and functions reliably in clinical cases.     

Myoperitoneal Microvascular Free Flaps in Dogs: An Anatomical Study and a Clinical Case Report

The purpose of the anatomical study was to identify potential myoperitoneal microvascular free flaps, in dogs, that are based on a single artery and vein. The angiosomes of the right deep circumflex iliac artery and left phrenicoabdominal (cranial abdominal) artery were evaluated in six medium-sized canine cadavers. The right deep circumflex iliac artery and left phrenicoabdominal (cranial abdominal) artery were injected with a mixture of barium and latex (equal parts). The entire right and left transversus abdominis muscles were dissected from the abdominal wall and radiographed. The angiograms of the deep circumflex iliac artery showed poor arborization of the vessels within the transversus abdominis muscle in all six cadavers. The angiograms of the phrenicoabdominal (cranial abdominal) artery showed consistent filling of the vascular bed of the cranial half of the transversus abdominis muscle flap in all six dogs. The vascular pedicle lengths and the diameter of the arteries and veins of both the deep circumflex iliac and phrenicoabdominal (cranial abdominal) myoperitoneal free flaps were found to be acceptable for microvascular anastomosis. The deep circumflex iliac flap was unacceptable because of inadequate vascular perfusion. The cranial abdominal artery had a consistent, large branch that supplied the cranial half of the transversus abdominis muscle, thereby making a myoperitoneal flap supplied by this vessel a potentially useful free flap. An 8-year-old male, neutered, mixed-breed dog was evaluated for possible repair of a large defect of the hard palate. Previous operations, using local tissue flaps, had been unsuccessful. A myoperitoneal free flap, based on the right cranial abdominal artery, and consisting of the cranial portion of the transversus abdominis muscle, was used successfully to reconstruct the hard palate. Migrating epithelium from the edges of the wound covered the myoperitoneal flap by 10 weeks after surgery. Therefore, the cranial abdominal myoperitoneal free flap can be considered for reconstruction of intra-oral defects that cannot be repaired using conventional local flap techniques.     

Use of the scrotum as a transposition flap for closure of surgical wounds in three dogs

OBJECTIVE: To describe use of the scrotum as a pedicle flap to cover defects created by tumor excision in the perineum or caudal and medial aspect of the thigh. STUDY DESIGN: Clinical study. ANIMALS: Three dogs. METHODS: After tumor excision and prescrotal castration, an incision was made around the base of the scrotum, leaving a pedicle on the side opposite the skin defect. After removal of the tunica dartos and abdominal fascia, the scrotal skin was stretched and shaped to the defect, then sutured in position with a simple interrupted pattern. Bandages that were changed every 48 hours compressed the flaps, and healing was observed until sutures were removed. RESULTS: Two dogs had first intention healing in 15 days, whereas 1 dog developed necrosis of 10% of the flap, and this area healed by second intention. CONCLUSION: In male dogs, the scrotal skin can be used as a pedicle flap for reconstructive surgery of wounds in the perineum and the proximomedial and caudal aspect of the thigh. CLINICAL RELEVANCE: The perineal region remains a surgical challenge because of the lack of the available skin for reconstruction of surgical wounds. The scrotal skin should be considered for use as a transposition flap to cover skin defects in this region.     

Axial pattern flap based on the lateral caudal arteries of the tail in the dog: an experimental study

OBJECTIVE: To determine applicability and size limits of an axial pattern flap based on the lateral caudal arteries in dogs to reconstruct caudodorsal trunk skin defects. STUDY DESIGN: Experimental study. ANIMALS: Ten mature, mixed breed dogs. METHODS: The lateral caudal vessels of the tail were incorporated in the flaps of the treatment group (n=5) and were ligated in the control group (n=5). Flaps were rotated and placed into experimentally created caudodorsal skin defects on the trunk. The length and area of tissue that remained viable in each flap were determined. RESULTS: Mean (+/-SD) survival area (222.8+/-32.9 cm2) and length (25.1+/-4.5 cm) of vascularized flaps were significantly greater (P<.05) compared with control flaps (94.9+/-13.4 cm2 and 14.61+/-4.7 cm). Necrosis occurred in all control flaps, resulting in lower percentage flap area (48.8%) and length (47.1%) survival compared with vascularized flaps (78.1%, 77.5%). CONCLUSIONS: Axial pattern flap based on lateral caudal arteries of the tail was successfully elevated and transferred in a single procedure, with 78% survival for closure of large experimentally created caudodorsal trunk defects in dogs. CLINICAL RELEVANCE: Large cutaneous defects of the caudodorsal trunk area in dog could be reconstructed with tail axial pattern flap. Limitations in terms of size and changes in animal appearance have to be considered before flap elevation.     

Distant abdominal and thoracic pedicle skin flaps for treatment of distal limb skin defects

The treatment of large skin defects of the distal limbs of dogs and cats can be difficult due to the lack of skin available for primary wound closure or the creation of local skin flaps. Distant pedicle skin flaps provide an acceptable alternative for wound closure with full thickness skin and provide a cosmetic result. Fourteen animals (10 dogs and four cats) that had distant pedicle skin flaps are reviewed. The technique allowed 100 per cent wound coverage in 10 of 14 animals and greater than 95 per cent skin flap survival occurred in 12 of 14 animals. Complications associated with the procedure were most commonly wound infection and partial suture line dehiscence, however these did not detract from the final outcome. Flap release was in one or two stages, however the outcomes did not appear to be affected by the release protocol.     

Effect of Two Muscle Sling Techniques on Early Morbidity after Femoral Head and Neck Excision in Dogs

Femoral head and neck excision was performed on the left coxofemoral joint of 18 dogs. The osteotomy site was padded with a partial-thickness biceps femoris muscle sling in one group of six dogs, and with a deep gluteal muscle flap in another group of six dogs. In a third group of six dogs, a partial-thickness biceps flap was created and sutured back in its original location. The dogs were monitored daily for 3 weeks for degree of lameness, range of motion, fever, and postoperative complications. Dogs with intra-articular muscle pads were less lame and had a greater range of motion in the treated hip than dogs without intra-articular muscle pads. Dogs with biceps slings showed more improvement in limb function and range of motion than did dogs with deep gluteal flaps. There were no significant differences in mean temperature elevations and no clinically significant postoperative complications. Use of a partial-thickness biceps muscle sling or a deep gluteal muscle flap decreased the chances of early postoperative morbidity and provided an earlier return to function. The partial-thickness biceps sling appeared to be more beneficial than the deep gluteal flap.     

Axial pattern flap based on a cutaneous branch of the facial artery in cats

Objective: To describe the cutaneous portion of the facial artery in cats and an axial pattern flap based on a branch of this artery. Study Design: Ex vivo study. Sample Population: Cat cadavers (n=12). Methods: The common carotid artery was identified, cannulated, and infused with methylene blue to assist in the identification of the facial artery, which was subsequently cannulated and selectively infused with methylene blue. The main trunk of the artery and its branches were dissected. The extent of blue coloration of the skin was evaluated on the contralateral side of the same specimen after infusing methylene blue into the facial artery. In 4 specimens, the flap was raised along previously defined borders and adequacy of perfusion was evaluated. Results: The area of skin perfused by the facial artery extended from the lower eyelid dorsally, to the angularis oris cranially, and the wing of the atlas caudally. Borders of the skin flap were defined on the basis of the anatomic dissection and skin coloration after selective infusion of the facial artery with methylene blue. A skin flap of 6 cm × 3.4 cm, based on the first caudally directed cutaneous branch of the facial artery was shown to be well perfused. The viability of this flap was confirmed in a clinical case. Conclusion: The facial artery flap is useful for repair of skin defects of the head in cats.     

Computed tomographic anatomy of the canine cervical vertebral venous system

Computed tomographic (CT) venography of the cervical vertebral canal was performed in six, clinically normal, adult mixed-breed dogs from 14 to 23 kg. After dogs were euthanized and saline perfused, a gelatin and iothalamate mixture was injected into the right external jugular vein. Contiguous, 4-mm-thick CT images were obtained with dogs in sternal recumbency. Dogs were kept in the same position as for the CT scan and frozen to approximately -8 degrees C. All post-contrast CT images were analyzed using similar bone window and level settings. Additional multiplanar reformatted dorsal images were obtained in all dogs. The frozen cadavers were sectioned through the cervical region extending from the occiput to T1 at approximately 8-mm intervals. The frozen sections were then compared with the CT images. The CT appearance of the normal cervical vertebral venous system was described and illustrated. Components such as the internal vertebral venous plexus, interarcuate veins, intervertebral veins, and vertebral veins were clearly identified on the CT images.     

Caudal Sartorius Muscle Flap in the Dog

An anatomic study was performed on canine cadavers to define the blood supply to the caudal sartorius muscle. The vascular supply to this muscle was segmental with the saphenous artery and vein providing a distal vascular pedicle. Anastomotic channels existed between distal and proximal capillary beds within the muscle belly. This anatomic information was used to determine the feasibility of performing caudal sartorius muscle flaps in dogs. The caudal sartorius muscle was transposed to the medial tibial region in four dogs. The muscle flap was based on a singular vascular pedicle of the saphenous artery and vein. The muscle transpositions were all successful on day 14 as evidenced by gross appearance and results of histologic examination. Grossly, the muscles were well adhered to the recipient sites and were covered by connective tissue. Histologically, the specimens were characterized by viable skeletal muscle fibers, large amounts of granulation tissue, varying degrees of inflammatory response, and small foci of myocyte necrosis (2 cases). Seroma formation was a consistent postoperative complication.     

Facial reconstructive surgery

Reconstruction of facial defects can be very challenging, even in the hands of an experienced surgeon. Most defects can be repaired using local available tissues. Lip defects can be reconstructed using geometric closure techniques and advancement of local tissues. Forehead defects can be reconstructed using skin grafts, caudal auricular flaps, or rotational or transposition flaps. Care must be taken to minimize tension on eyelids and maintain the integrity of the facial nerve. Cheek defects can be reconstructed using local advancement, superficial temporal, omocervical, and caudal auricular flaps. The bridge of the nose can be very difficult to reconstruct due to a paucity of local tissues; however, skin grafts, indirect pedicle flaps, and superficial temporal flaps can be considered. .     

Applications of a semitendinosus muscle flap in two dogs

The proximal half of the semitendinosus muscle can be used as a versatile vascularized local transposition flap to reconstruct anatomic faults in the adjacent perineum in dogs. The flap is easy to dissect, and the arc of rotation is considerably beyond the midline. The location, size, and direction of the major vascular pedicle from the caudal gluteal artery is conducive to dependable flap perfusion.     

A Comparison of the Cutaneous Trunci Myocutaneous Flap and Latissimus Dorsi Myocutaneous Flap in the Dog

Latissimus dorsi and cutaneous trunci myocutaneous flaps of equal dimension and location were randomly elevated on opposite sides of the thorax in 10 dogs (group 1) and resutured to their respective bed. The procedure was repeated in four additional dogs (group 2); however, the short perforating branches of the thoracodorsal artery and vein were divided at the base of each cutaneous trunci myocutaneous flap, whereas the cutaneous pedicle and underlying cutaneous trunci muscle were divided in the latissimus dorsi myocutaneous flaps to determine subsequent skin survivability and the major source of circulation of each myocutaneous flap. There was little difference in the percentage of skin survival between the latissimus dorsi and cutaneous trunci myocutaneous flaps in group 1 dogs. Circulation to the "skin island" of group 2 latissimus dorsi myocutaneous flaps originated from intramuscular anastomotic connections between the major branch of the thoracodorsal artery entering the latissimus dorsi muscle and the proximal lateral intercostal arteries perforating the muscle. Ligation of the short perforating branches of the thoracodorsal artery resulted in partial skin necrosis in all group 2 cutaneous trunci myocutaneous flaps. Results from this study indicate that it is unnecessary to elevate the latissimus dorsi muscle for major skin flap elevation and survival. The thicker latissimus dorsi myocutaneous flap is more difficult to develop surgically and appears to have no clinical major advantage over the more mobile cutaneous trunci myocutaneous flap or the adjacent thoracodorsal axial pattern flap for closure of large skin defects within the radius of flap rotation.     

Skin-fold advancement flaps for closing large proximal limb and trunk defects in dogs and cats

OBJECTIVE: To describe the use of skin-fold advancement flaps for covering large skin defects in dogs and cats. STUDY DESIGN: Clinical study. ANIMALS: Eight client-owned animals: 6 dogs and 2 cats. METHODS: Six dogs and 2 cats underwent reconstruction of soft-tissue wounds resulting from traumatic, neoplastic, or infectious lesions. Skin-fold flaps were created by division of the medial and lateral attachment to the proximal limb or the dorsal and ventral attachment to the trunk, enabling closure of adjacent defects on the trunk or proximal limb, respectively. RESULTS: Skin-fold flaps proved effective for closing defects in all animals. Necrosis of a portion of the flap occurred in 2 dogs due to technical errors, but the resultant defects remained amenable to primary closure. All wounds ultimately healed primarily, without major complications. CONCLUSION AND CLINICAL RELEVANCE: The skin-fold advancement flap is a versatile technique that lends itself to use in a variety of locations, depending on which attachments are divided. The clinical results are comparable with those reported for axial pattern and subdermal plexus flaps.     

A vaginal mucosal pedicle flap technique for repair of rectovaginal fistula in mares

OBJECTIVE: To describe the use of a vaginal mucosal pedicle flap for repair of rectovaginal fistulae (RVF) in mares. STUDY DESIGN: Clinical case report. ANIMALS: Three mares with RVF. METHODS: After debriding the RVF, a dorsally based U-shaped mucosal and submucosal pedicle flap (2-4 mm thick) was dissected from the vaginal wall, rotated approximately 90 degrees angle to close the ventral aspect of the fistula and sutured in position with 10-13 single sutures that did not penetrate the rectal mucosa. This positioned the vaginal mucosa so that it was continuous with the rectal mucosa. RESULTS: Two RVF healed by 1st intention whereas for the 3rd RVF, 2 additional single sutures were required to repair partial dehiscence after 10 days. At 6 weeks and 6 months all RVF were healed. One mare subsequently foaled without complications. CONCLUSIONS: RVF can be closed by use of a rotation flap of vaginal tissue. CLINICAL RELEVANCE: Tension-free closure of RVF can be achieved by rotating a pedicle flap of vaginal mucosal tissue without undue wound tension, and should be considered as an alternative to conventional appositional techniques.     

Angularis oris axial pattern buccal flap for reconstruction of recurrent fistulae of the palate

OBJECTIVE: To describe the use of an axial pattern flap based on the angularis oris artery and vein for reconstruction of palate defects. STUDY DESIGN: Clinical case report ANIMALS: Two dogs with recurrent oronasal fistulae. METHODS: Oronasal fistulae previously treated by buccal mucosal random pattern flaps that subsequently dehisced were repaired using an angularis oris-based buccal tissue axial pattern flap. This flap was developed by full thickness incision of the cheek tissue, excluding the skin, about the angularis oris vascular pedicle resulting in a vascularized flap covered by oral mucosa on one side. RESULTS: In one dog, the repair was intact and healed 6 months after surgery. In the second dog with a fistula that resulted because of radiation necrosis, approximately 95% of the defect healed with a small (<1.0 cm(2)) area of dehiscence. Repair of this persistent fistula with a random pattern buccal flap failed and this small fistula remained with minimal clinical signs. CONCLUSION: An axial pattern flap based on the angularis oris artery and vein can be used to repair difficult or recurrent palate defects. CLINICAL RELEVANCE: Angularis oris axial pattern flaps provide an additional effective option for repair of defects in the hard and soft palate to the distal gingival margin of the canine tooth or beyond, depending on skull conformation. Advantages of this flap include its highly vascular and robust character, high degree of mobility and a surface of tough buccal mucosa.     

Abdominal Wall Reconstruction with a Vascular External Abdominal Oblique Myofascial Flap

A myofascial island flap for abdominal wall reconstruction was based on the lumbar component of the external abdominal oblique muscle and supplied by a major neurovascular pedicle consisting of branches of the cranial abdominal artery, cranial hypogastric nerve, and a satellite vein. The flap was elevated and sutured into a 10 cm x 10 cm body wall defect in five dogs. The dogs were observed for 26 to 28 days. Abdominal wall contour and function were preserved. All dogs developed seromas, two of which became infected. One dog developed a hernia at the dorsal margin of the flap, which was repaired. At necropsy, there was no evidence of dehiscence in any of the dogs. Loose adhesions of omentum to the inner surface of the flap occurred in four dogs. Results of histologic examination confirmed the clinical impression of flap viability. The myofascial island flap has a wide range of mobility over the ventral and caudal areas of the abdomen and lateral thoracic wall. It has potential clinical use for reconstruction of defects within its arc of rotation.     

Complications and outcome after thoracodorsal axial pattern flap reconstruction of forelimb skin defects in 10 dogs, 1989-2001

OBJECTIVE: To determine (1) the frequency and extent of complications associated with thoracodorsal axial pattern flap reconstruction of forelimb skin defects in dogs and (2) outcome after treatment of such complications. STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Ten dogs. METHODS: Medical records for 10 dogs that had a thoracodorsal axial pattern skin flap reconstruction of a forelimb skin defect were reviewed. RESULTS: Three dogs had complete flap survival. Partial necrosis of the distal flap, ranging from an estimated 2% to 53% (mean, 21%) of the flap surface area, occurred in 7 dogs. Six dogs required surgical management of the skin necrosis, resulting in successful resolution in 5 dogs, whereas, in 2 dogs, the wound healed by second intention. Positive bacterial cultures were obtained from 3 dogs with distal flap necrosis. Seroma formation was noted in 2 dogs; the entire flap survived in 1 dog, whereas the second dog developed distal flap necrosis. Edema and bruising of the distal portion of the flap were noted in 8 dogs; distal flap necrosis subsequently developed in 7 dogs. Partial incisional dehiscence, which healed by second intention, occurred in 2 dogs. Of 6 owners available for follow-up, all were satisfied with the functional outcome, but 1 owner was not satisfied with the cosmetic appearance. CONCLUSIONS: Partial flap necrosis was a frequent complication of thoracodorsal axial pattern flap reconstruction of forelimb skin defects and required additional wound care or surgical intervention to achieve healing. CLINICAL RELEVANCE: Thoracodorsal axial pattern flaps can provide full-thickness skin coverage of extensive skin defects of the forelimb, but owners should be aware of the likelihood of local wound complications.     

Direct cutaneous arterial supply to the tail in dogs.

Cutaneous arterial blood supply to the tail was evaluated in 12 dogs. Subtraction radiography of internal iliac artery and distal aorta angiography in 3 of these dogs was used to determine arterial blood supply to the tail from the median sacral and lateral caudal arteries. Dissection of the tail in 8 canine cadavers revealed bilateral subcutaneous location of lateral caudal arteries following tail amputation. An axial pattern flap based on the lateral caudal arteries contributed to the reconstruction of a large caudodorsal cutaneous defect in a dog. An axial pattern flap based on the lateral caudal arteries following tail amputation may be indicated to aid reconstruction of large caudodorsal cutaneous defects of the trunk in dogs.     

Cranial Sartorius Muscle Flap in the Dog

An anatomic study was performed on canine cadavers to define the blood supply to the cranial sartorius muscle. The vascular supply to this muscle was found to be a single dominant pedicle branching from the femoral artery at the proximal portion of the muscle. This anatomic information was applied in designing a study to determine the feasibility of performing a cranial sartorius muscle flap in the dog. The cranial sartorius muscle was transposed to the caudal abdominal region in four dogs. The muscle flap was based on the singular vascular pedicle defined in the anatomic study. All muscle transpositions were successful on day 19 as evidenced by gross appearance and histologic examination. Grossly, the muscles were well adhered to the recipient sites and were covered by connective tissue. Histologically, the specimens were characterized by viable skeletal muscle fibers, proliferative and maturing granulation and fibrous connective tissue, and mild to moderate mononuclear inflammation. Seroma formation and infection were the two postoperative complications noted. The cranial sartorius muscle flap has potential clinical application for repair of traumatic caudal abdominal hernias and large inguinal hernias in the dog.