Perfusion and viability of island axial pattern skinflaps were tested in 37 healthy New Zealand white rabbits, using laser Doppler monitoring of blood flow in the capillary loops and the subpapillary plexus of the dermis. Skin flaps, selected on the basis of the caudal superficial epigastric vein and artery, were lifted and replaced in their original locus after selective occlusion of their vascular pedicles. Subjects were allotted into groups: control group (n = 10); arterial occlusion (n = 7); venous occlusion (n = 10); and arterial and venous occlusion (n = 10). The rabbits were monitored from 48 hours before surgery until euthanasia 48 to 72 hours after replacement of the flap. Flap viability was assessed on a clinical basis, using a comparative scoring method based on a numeric scale. The degree of necrosis in histologic sections was evaluated, using a scoring system. Laser Doppler measurements were obtained on 3 consecutive days before surgery, to establish the normal basal blood flow in the skin. Postsurgical measurements were obtained at 2-hour intervals for the first 8 hours and at 24, 48, and 72 hours after surgery. Measurements of basal blood flow varied significantly (P < 0.05) from site to site on the surface of individual flaps and over time. When laser Doppler flowmetric (LDF) measurements from 6 sites on a flap were used as a measure of laser Doppler flow for the total flap, there was no significant difference between contralateral flap areas outlined on the abdomen of the rabbits. Temporal variations over 3 days for each rabbit or among rabbits were not significant. The LDF measurements detected acute vascular occlusion when compared with the controls, and were able to differentiate between control and arterial occlusion groups, control and venous occlusion groups, control and arterial and venous occlusion groups, arterial and venous occlusion groups, venous and arterial and venous occlusion groups (P < 0.05), but not between arterial and arterial and venous occlusion groups. Evaluation of LDF values at 4 hours proved to be a better predictor than clinical assessment at 4 or 8 hours in evaluating skin flap viability.

Free, autogenous, full-thickness skin grafts were applied to 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given an equal volume of 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). All dogs (DEF-HES/HBO- and HES/HBO-treated) were exposed to 60 minutes of hyperbaric oxygen (HBO) at 2 atmospheres absolute pressure twice daily for 10 days, beginning the day of surgery. The percentage of viable graft on day 10 was lower in HES/HBO-treated-dogs (mean +/- SD, 13.3 +/- 21.3%; median, 3.0%) than in DEF-HES/HBO-treated dogs (64.7 +/- 39.2%; 88.3%; P = 0.095, Mann-Whitney two-tailed test). There was a positive correlation between percentage of viable graft (on day 10) and percentage of haired skin on the graft site (on day 28) for all dogs (r = 0.91) and for HES/HBO-treated dogs (r = 0.97). The DEF-HES/HBO-treated dogs had less consistent correlation (r = 0.67). Perivascular aggregates of foamy cells were observed in the superficial and reticular portions of the dermis and in the subcutaneous tissue on both surfaces of the panniculus muscle in the graft sites of DEF-HES/HBO-treated dogs. These cells were also observed in the dermis, but not subcutaneous tissue of the control skin sections, and in some viscera of DEF-HES/HBO-treated dogs. Deferoxamine appears to attenuate the detrimental effect of HBO and HES on survival of free skin grafts. However, clinical use of HBO is not recommended as adjunct treatment for free skin grafts in dogs in the first 10 days after grafting. Administration of DEF-HES is not recommended because it has failed to improve the survival of free skin grafts, and the consequence of the cellular response seen in this study is undetermined.

Free, autogenous, full-thickness skin grafts were applied to 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given an equal volume of 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). All dogs (DEF-HES/HBO- and HES/HBO-treated) were exposed to 60 minutes of hyperbaric oxygen (HBO) at 2 atmospheres absolute pressure twice daily for 10 days, beginning the day of surgery. The percentage of viable graft on day 10 was lower in HES/HBO-treated-dogs (mean +/- SD, 13.3 +/- 21.3%; median, 3.0%) than in DEF-HES/HBO-treated dogs (64.7 +/- 39.2%; 88.3%; P = 0.095, Mann-Whitney two-tailed test). There was a positive correlation between percentage of viable graft (on day 10) and percentage of haired skin on the graft site (on day 28) for all dogs (r = 0.91) and for HES/HBO-treated dogs (r = 0.97). The DEF-HES/HBO-treated dogs had less consistent correlation (r = 0.67). Perivascular aggregates of foamy cells were observed in the superficial and reticular portions of the dermis and in the subcutaneous tissue on both surfaces of the panniculus muscle in the graft sites of DEF-HES/HBO-treated dogs. These cells were also observed in the dermis, but not subcutaneous tissue of the control skin sections, and in some viscera of DEF-HES/HBO-treated dogs. Deferoxamine appears to attenuate the detrimental effect of HBO and HES on survival of free skin grafts. However, clinical use of HBO is not recommended as adjunct treatment for free skin grafts in dogs in the first 10 days after grafting. Administration of DEF-HES is not recommended because it has failed to improve the survival of free skin grafts, and the consequence of the cellular response seen in this study is undetermined.

After removal of 1 metatarsal pad and formation of a granulation tissue bed, free segmental 6- X 8-mm grafts from digital pads were sutured into recessed same-size recipient sites in the granulation tissue. In 5 dogs, the grafted area had been denervated by excision of a segment of the tibial nerve at the level of the tarsus. The grafted area was not denervated in the remaining 5 dogs. In both groups of dogs, the grafts placed around the periphery of the wound healed, blocked ingrowth of delicate epithelium from the surrounding skin, and provided a tough keratinized epithelium that covered the wound's center. As healing progressed, the grafts coalesced as the wounds contracted. Weight bearing resulted in graft expansion to provide functional weight-bearing tissue. Dogs of the denervated group had clinical and histologic evidence of collateral sensory reinnervation of the denervated area. However, with the exception of 1 dog, results of sensory nerve action potential tests indicated that reinnervation may not have been by way of regeneration across the excisional gap in the nerve. Evaluation of reinnervation of the tibial autonomous zone in 2 additional dogs revealed clinical evidence that collateral reinnervation began between 19 and 28 days after nerve excision and progressed proximad to distad. Results of sensory nerve action potential tests indicated that reinnervation may not have been via regeneration across the excision site. Results of fluorescent tracer studies did not have positive findings regarding the route of collateral reinnervation. Segmental paw pad grafts can be used effectively to provide weight-bearing tissue on a dog's limb. With local nerve damage on the distal portion of the limb, collateral innervation can grow into the area to reinnervate tissues, including pad grafts.

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.

Areas of skin vascularized by large axial vessels potentially suitable for microvascular anastomosis were investigated in 10 horse cadavers. Eleven such areas were dissected, and the skin over the flank region vascularized by the deep circumflex iliac artery was most suitable. The anatomy of this area was further defined, using angiography and latex injection studies on 10 cadavers.

Perfusion and viability of island axial pattern skinflaps were tested in 37 healthy New Zealand white rabbits, using laser Doppler monitoring of blood flow in the capillary loops and the subpapillary plexus of the dermis. Skin flaps, selected on the basis of the caudal superficial epigastric vein and artery, were lifted and replaced in their original locus after selective occlusion of their vascular pedicles. Subjects were allotted into groups: control group (n = 10); arterial occlusion (n = 7); venous occlusion (n = 10); and arterial and venous occlusion (n = 10). The rabbits were monitored from 48 hours before surgery until euthanasia 48 to 72 hours after replacement of the flap. Flap viability was assessed on a clinical basis, using a comparative scoring method based on a numeric scale. The degree of necrosis in histologic sections was evaluated, using a scoring system. Laser Doppler measurements were obtained on 3 consecutive days before surgery, to establish the normal basal blood flow in the skin. Postsurgical measurements were obtained at 2-hour intervals for the first 8 hours and at 24, 48, and 72 hours after surgery. Measurements of basal blood flow varied significantly (P < 0.05) from site to site on the surface of individual flaps and over time. When laser Doppler flowmetric (LDF) measurements from 6 sites on a flap were used as a measure of laser Doppler flow for the total flap, there was no significant difference between contralateral flap areas outlined on the abdomen of the rabbits. Temporal variations over 3 days for each rabbit or among rabbits were not significant. The LDF measurements detected acute vascular occlusion when compared with the controls, and were able to differentiate between control and arterial occlusion groups, control and venous occlusion groups, control and arterial and venous occlusion groups, arterial and venous occlusion groups, venous and arterial and venous occlusion groups (P < 0.05), but not between arterial and arterial and venous occlusion groups. Evaluation of LDF values at 4 hours proved to be a better predictor than clinical assessment at 4 or 8 hours in evaluating skin flap viability.

Free, autogenous, full-thickness skin grafting was performed on 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). The percentage of viable graft on day 10 was higher, but not significantly so, in DEF-HES-treated dogs (mean +/- SD, 72.6 +/- 24.8%; median 76.5%) than in HES-treated dogs (mean +/- SD, 46.7 +/- 34.3%; median, 48.8%). A trend for a positive correlation between the percentage of viable graft (on day 10) and the percentage of original graft area (on day 28) was observed in HES- and DEF-HES-treated dogs; this trend was significant in HES-treated dogs (P = 0.012). Both groups had significant positive correlation between percentage of viable graft on day 10 and percentage of haired skin on day 28 (HES, P = 0.000002; DEF-HES, P = 0.0148). A unique finding in DEF-HES treated dogs was the consistent observation of foamy macrophages in the dermis adjacent to the grafts, in deep subcutaneous tissue below the grafts, and in normal dermis.

We developed a single-pedicle, axial pattern tubed skin flap that could be transferred to an in vitro perfusion apparatus. On the basis of results of prosections, angiography, contact radiography, and surviving-length studies, it was concluded that a single-pedicle, axial pattern skin flap measuring 4 cm X 12 cm incorporating the caudal superficial epigastric artery would survive to its entire length. Subsequently, a surgical (stage 1) procedure was developed for the routine preparation of single-pedicle, axial pattern tubed skin flaps. Healing after the stage-1 procedure was evaluated by visual inspection and fluorescein angiography. Stage-1 procedures were performed successfully 149 of 160 (93%) times. A second surgical (stage 2) procedure was developed for routine cannulation of the caudal superficial epigastric artery and harvest of the tubed skin flap. Stage-2 procedures were performed successfully 136 of 144 (94%) times.