Benefits of primary wound closure in comparison to open wound management include simpler wound care for clients, faster wound healing, reduced pain, less scarring, and protection of underlying structures.1 Other possible benefits include less bandaging and more aesthetically pleasing results.1 In veterinary medicine, subdermal plexus flaps, axial pattern flaps, myocutaneous flaps, and skin grafts have been described to facilitate primary wound closure. Axial pattern flaps are skin flaps that incorporate a direct cutaneous artery and vein at their base.2 This allows for the utilization of a larger area of skin.2 Axial pattern flaps are used in veterinary medicine commonly for closure of large wounds after trauma or tumor removal when primary wound closure cannot be achieved.3,4 Measurements of the open wound bed and margins of the axial pattern flap are obtained preoperatively and/or intraoperatively to plan for surgery.4 Axial pattern flaps can be rotated up to 180° at the base to cover the defect; rotations greater than 180° can cause vessel occlusion and flap necrosis.4 The flap should be elevated deep to the cutaneous trunci muscle or equivalent to preserve the vessels.4 Defects in the perineum and tail can be difficult to manage due to fecal and urine contamination and dehiscence secondary to motion or self-mutilation.5 Additionally, bandaging this region can be challenging as bandages can easily become dislodged or soiled.5 Successful closure of wounds in the caudal dorsum and perineum has been described with local flaps from the dorsal lumbar skin and scrotal skin.5,6 Axial pattern flaps are reported to have higher and more consistent survival rates as compared to flaps without direct cutaneous vessels.4,7 The deep circumflex iliac artery, caudal superficial epigastric artery, and lateral caudal artery can provide specific axial pattern flaps to close wounds in the gluteal, perineal, sacral, and tail areas.7–11 The dorsal perineal artery has recently been evaluated as a source of an axial pattern flap in the cat and dog.12–14 To the authors’ knowledge, the angiosome of the caudal gluteal artery in the dog has not been previously examined. The objectives of this study were to identify the cutaneous artery of the caudal gluteal artery on CT angiography and to evaluate its angiosome in the dog (cadaveric and radiographic angiography) with establishment of landmarks for its use as a caudal gluteal axial pattern (CGAP) flap. The hypothesis is that the angiosome of the cutaneous artery of the caudal gluteal artery is consistently present and consistently extends over the caudal hip region for in vivo use.
Methods
Retrospective review of CT studies
Twenty client-owned dogs (5 to 55 kg) received contrast CT scans for reasons unrelated to this study; scans were performed between July 2019 and July 2020 and randomly chosen before the cadaver study. Eligibility criteria required postcontrast whole body CT scans including the entire pelvic region, pelvic limbs, and tail. Patient data including age, sex, breed, and weight were available. Computed tomography scans with abnormal anatomy (eg, tumors, wounds) in the pelvic region and pelvic limbs were excluded from the study. Incomplete scans and scans with asymmetric positioning were also excluded from the study. Anesthetized dogs were previously positioned in dorsal or ventral recumbency for whole body scans with the hind limbs pulled caudally or kept in a neutral to flexed frog-legged position. All dogs received IV iohexol (Omnipaque 300; GE Healthcare; 660 mg I/kg, IV). The CT images were acquired in 3-mm slice thickness in transverse and sagittal planes with a pitch factor of 0.844 (Aquilion 16 slice CT scanner; Toshiba). Images were viewed and evaluated in the soft tissue window. Decisions for inclusion and exclusion criteria were performed by a consensus of the 2 authors, a surgery intern (THC) and a board-certified veterinary surgeon, American College of Veterinary Surgeons (DAD). Authors DAD and THC reviewed all scans to confirm the presence and location of the direct cutaneous artery of the caudal gluteal artery in relation to the greater trochanter of the femur.
Anatomical study in cadavers
Six canine cadavers (12 pelvic limbs) were donated from an animal control facility for study purposes. Dogs were of mixed breed and 20 to 30 kg in size. All dogs were euthanized for reasons unrelated to this study. Three cadavers were fresh; 3 cadavers were frozen immediately after euthanasia, stored at −20 °C, and then thawed to room temperature for dissection. Each pelvic limb was clipped from the dorsal midline to the lateral stifle and caudal thigh. Additionally, the caudolateral and ventral abdomen and perineum were clipped. A caudal midline celiotomy was made and the aortic bifurcation was identified. A small stab incision was made in the aorta just cranial to the external iliac arteries. An 8-Fr red rubber catheter was inserted normograde into the stab incision and advanced into the internal iliac artery. The red rubber catheter was secured with a circumferential ligature around the aorta 0.5 cm distal to the internal iliac arteries. The external iliac arteries were each clamped with hemostats to prevent redirection of barium. Sixty milliliters of barium sulphate (Liquibar; 60% [w/w] barium sulphate; E-Z EM) was injected into the internal iliac artery via the red rubber catheter. Dissections and barium injections were performed with the same procedure in the contralateral internal iliac artery and limb. After barium injection, the cadavers were placed in left and right lateral recumbency for 5 minutes on each side. Borders for skin dissection were developed from a retrospective review of the CT scans to include the course of the direct cutaneous artery. The following landmarks were used in the dissection process: the iliac crest, greater trochanter and femur, stifle, ischiorectal fossa, and ischiatic tuberosity. The landmarks were mapped on the skin of each cadaver with a marker. The cranial border was made with a linear incision approximately 3 cm cranial to the crest of the ilium, from the dorsal midline to the cranial inguinal region. The dorsal border was made with a linear incision along the dorsal midline. The caudal border was made with an incision approximately 3 cm medial to the ischiatic tuberosity, from the tail base to the perineum and caudal thigh. The ventral border was made with a U-shaped incision at the level of the distal femur, just proximal to the patella. The cutaneous vessels were grossly visualized and care was taken to ensure preservation of the vessels within the hypodermis. The skin and hypodermis over the lateral hip and proximal thigh regions were removed, including all landmarks. The direct cutaneous artery was traced on the skin with a marker for review. Radiographic angiograms of the skin flaps were taken and positioned on the x-ray table with the drawn landmarks visible, as a record of positioning for future reference if needed. The excised skin flaps, from left and right sides, were photographed and radiographed with a high-definition digital radiography machine (Cuattro DR; Heska). Cadavers were processed and evaluated during the same session. The angiosomes were identified both on gross inspection and radiographs to evaluate the vascular supply of the cutaneous artery (branch) of the caudal gluteal artery. The angiograms were compared to the landmarks drawn on the skin to establish anatomical borders and perfusion of the direct cutaneous artery.
Results
Preliminary CT studies
The caudal abdomen, spine, pelvis, and pelvic limbs were normal in all 20 scans. The CT scans of all 20 dogs demonstrated a common arterial trunk that initially extended from the caudal gluteal artery at the level of the hip joint through the greater ischiatic notch. The vessel was then further divided into the lateral caudal artery and a direct cutaneous artery that continued through the subcutaneous fat to the skin (Figure 1). The path of the direct cutaneous artery had a slight variation of its location relative to the greater trochanter depending on the dog (Supplementary Table S1). Thirteen of 20 dogs were positioned in ventral recumbency and 7/20 in dorsal recumbency. In 3/20 dogs, the cutaneous artery traveled cranial to the greater trochanter. The cutaneous artery traveled dorsal and lateral relative to the greater trochanter in 9/20 dogs and caudal to the greater trochanter in 8/20 dogs (Figure 2). The path of the cutaneous artery was symmetric and present bilaterally in all 20 CT scans.
Transverse postcontrast CT image at the level of S1-S2 showing the emergence and branching of the cutaneous artery branch of the caudal gluteal artery (arrow). Window width, 300 HU; window level, 45 HU; 3-mm slice thickness. D = Dorsal. GT = Greater trochanter. L = Left. R = Right. V = Ventral.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.04.0094
Schematic diagram illustrating the branching of the cutaneous artery of the caudal gluteal artery with its pathway caudal to the GT. The cutaneous artery extends distally over at least the proximal one-quarter of the GT.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.04.0094
Outcome of cadaver study
The direct cutaneous artery was identified in all 12 hemipelves during dissection and preparation for angiography (Figure 3). Angiograms and skin thickness were symmetric in all hemipelves. Bilaterally, the cutaneous branch of the caudal gluteal artery extended over the superficial gluteal fascia at the level of the superficial and middle gluteal muscles. Depending on anatomic variation, the cutaneous branch traveled in the hypodermis over the lateral aspect of the greater trochanter or over the cranial or caudal aspect of the greater trochanter (Figure 4). The branch continued to divide into smaller branches, which were grossly visualized in the hypodermis over the proximal fourth of the lateral thigh over the tensor fascia lata muscle and biceps femoris fascia. The angiographic pattern was visualized in all 12 hips on radiographs (Figure 5). The course of the direct cutaneous artery had some minor variability on the radiographs but was located either just over the cranial aspect of the greater trochanter, over the lateral aspect, or just caudal to the greater trochanter. As defined by the margins of the angiosome, the dorsal border of the CGAP flap was the dorsal midline; the base of the CGAP flap was the proximal aspect of the superficial/middle gluteal muscles, just distal to dorsal midline of the body. The maximal cranial border was halfway between the wing of the ilium and the greater trochanter. The maximal caudal border was halfway between the greater trochanter and ischiatic tuberosity. The distal (ventral) border is the proximal one-quarter of the thigh. The midsagittal plane of the flap was dependent on the path of the cutaneous vessels in each individual. Cranial and caudal incisions were contingent on the path of the cutaneous vessels in relation to the greater trochanter (cranial to vs lateral to vs caudal). The flap width was approximately 4 cm, and the flap length was approximately 7 cm.
Lateral view of the right hip region. The dissected cadaver skin has been reflected to reveal the cutaneous branch of the caudal gluteal artery, as well as its arborization (arrows). BF = Biceps femoris muscle. SG = Superficial gluteal muscle.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.04.0094
The borders for dissection of the skin flap in each cadaver were made with a marking pen over the skin. The cutaneous branch of the caudal gluteal artery and its arborization were marked over the skin on observation of its course during each dissection (arrows). The path of the cutaneous branch of the caudal gluteal artery, traveling caudal to the GT. IL = Iliac crest. IS = Ischiorectal fossa.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.04.0094
Lateromedial radiographic angiogram of a right hip showing the perfusion pattern of the cutaneous branch of the caudal gluteal artery (arrows). The branch started from dorsal midline and extended toward the proximal fourth of the femur. Ca = Caudal. DP = Dorsal perineal artery. S = Scrotum. VP = Ventral perineal artery.
Citation: American Journal of Veterinary Research 2025; 10.2460/ajvr.24.04.0094
Discussion
An angiosome based on a direct cutaneous artery of the caudal gluteal artery over the lateral hip region was identified in all dogs in this study. Landmarks and borders of the CGAP flap have been established with this study. In practice, the cranial and caudal borders may need to be narrower, not due to inadequate perfusion, but to allow for primary closure of the donor site. As in all flap development, individual variability of cutaneous blood supply may result in inadequate blood supply and distal flap necrosis.4 Contrast-enhanced CT is always recommended to identify perfusion patterns. In the dog, anatomical variations of the main branches of the internal iliac artery have been reported.15 However, the study by Avedillo and others15 did not extend their evaluation to cutaneous or more superficial vessels. Anatomic variations, body condition, and positioning on CT scans may potentially affect the path of the direct cutaneous vessel of the CGAP flap. A higher body condition score may lead to a more difficult dissection intraoperatively; additional research is needed to study this. If the hind legs are pulled caudally, this may skew the path of the direct cutaneous artery more caudal. Thus, the dissection may be erroneously more caudal. Positioning should be considered during CT scans and surgery and should be identical in both. Although lower in resolution, Doppler ultrasonography may be used adjunctively to confirm the location of the cutaneous artery.16
A presurgical CT scan will provide information regarding the presence and patency of the direct cutaneous artery and proximity of the vessel to the wound or tumor, if present. Additionally, presurgical CT scan can guide planning for specific flap length and width. The lateral caudal axial pattern flap is an alternative option for primary closure in the caudal dorsum and perineal region10,11; however, the CGAP flap provides another option and does not require sacrifice of the tail. Two other perineal flaps developed from the caudal thigh have been identified, which provide additional options for perineal and tail wound reconstruction.14 The CGAP flap is ideal for tail wound reconstruction as the base of the flap is located adjacent to the base of the tail. For considerably larger wounds located over the tail base or sacral region, other flaps may be required as the CGAP flap has size limitations. Additionally, the axial pattern blood supply may be damaged during tumor removal in these regions or at the time of initial wounding. Dog ears at the base of the flap postrotation may be avoided by creating an island flap rather than a peninsular flap; this warrants further investigation. Motion from the tail may increase the risk of incisional dehiscence.
In humans, the internal iliac artery branches into the superior gluteal artery and the inferior gluteal artery. These vessels are equivalent to the cranial gluteal artery and the caudal gluteal artery in the dog, respectively. Cutaneous perforators of the superior gluteal artery and inferior gluteal artery have been commonly used as a free skin/fat flap in humans.17 Recent studies17 have discussed the usefulness of these flaps for autologous breast reconstruction in postmastectomy patients. The septocutaneous gluteal artery perforator flap and the septocutaneous tensor fascia lata flap are alternative flaps that have been used for autologous breast reconstruction in humans.18 Previous studies17,19 also showed an absence or too small of an inferior gluteal artery perforator, in some humans, for an axial pattern flap in comparison to the superior gluteal artery perforator. A direct cutaneous artery from the cranial gluteal artery has not been identified in the dog.
A limitation of this study was that this was an anatomic study, rather than a physiologic one. The barium sulphate allowed excellent visualization of the angiosome but in vivo studies are needed. An experimental live dog study, including islanding the flap, or a series of clinical cases would further substantiate the survivability of the CGAP flap. Another limitation of the study was inconsistency in positioning of the CT scans. Further studies with preoperative CT scan with a set protocol would help guide consistency in localizing and planning for flap surgery.
In conclusion, the direct cutaneous artery of the caudal gluteal artery in the dog was identified in all CT scans in the retrospective evaluation. The angiosome was present in all cadavers, consistently extending over the caudal hip region. The angiosome was bilateral and symmetric with slight individual variation. The findings in this study suggest that the direct cutaneous artery of the caudal gluteal artery in the dog may maintain the viability of a CGAP flap. The CGAP flap can be considered to close wounds in the caudal sacral region, proximal gluteal region, perineum, and proximal tail areas. Studies are needed to look at the effects of individual variability, such as body condition, and positioning. Further studies are also needed to investigate flap survival, complications, and cosmetic outcomes.
Supplementary Materials
Supplementary materials are posted online at the journal website: avmajournals.avma.org.
Acknowledgments
We thank Bryden J. Stanley, BVMS, MVetSc, DACVS, for contributions during manuscript editing. The content of this study was presented in ePoster form at the American College of Veterinary Surgeons Annual Surgery Summit on October 15, 2020.
Disclosures
The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.
Funding
The research was funded by the authors’ departments.
References
- 1.↑
Fahie MA. Primary wound closure. In: Johnston SA, Tobias KM, eds. Veterinary Surgery: Small Animal. 2nd ed. Vol 2. Elsevier Saunders; 2018:3787.
- 2.↑
Wardlaw JL, Lanz OI. Axial pattern and myocutaneous flaps. In: Johnston SA, Tobias KM, eds. Veterinary Surgery: Small Animal. 2nd ed. Vol 2. Elsevier Saunders; 2018:3915.
- 3.↑
Field EJ, Kelly G, Pleuvry D, Demetriou J, Baines SJ. Indications, outcomes and complications with axial pattern skin flaps in dogs and cats: 73 cases. J Small Anim Pract. 2015;56(12):698–706.
- 6.↑
Grigoropoulou VA, Prassinos NN, Papazoglou LG, Galatos AD, Pourlis AF. Scrotal flap for closure of perineal skin defects in dogs. Vet Surg. 2013;42(2):186–191.
- 7.↑
Pavletic MM. Canine axial pattern flaps, using the omocervical, thoracodorsal, and deep circumflex iliac direct cutaneous arteries. Am J Vet Res. 1981;42(3):391–406.
- 8.
Pavletic MM. Axial pattern flaps in small animal practice. Vet Clin North Am Small Anim Pract. 1990;20(1):105–125.
- 9.
Mayhew PD, Holt DE. Simultaneous use of bilateral caudal superficial epigastric axial pattern flaps for wound closure in a dog. J Small Anim Pract. 2003;44(12):534–538.
- 10.↑
Saifzadeh S, Hobbenaghi R, Noorabadi M. Axial pattern flap based on the lateral caudal arteries of the tail in the dog: an experimental study. Vet Surg. 2005;34(5):509–513.
- 11.↑
Montinaro VM, Massari F, Vezzoni L, et al. Lateral caudal axial pattern flap in 13 dogs. Vet Surg. 2015;44(5):642–647. doi:10.1111/j.1532-950X.2014.12305.x
- 12.↑
Murdoch AP, Grand JGR. An axial pattern flap based on the dorsal perineal artery in a cat. Aust Vet J. 2016;94(24):470–473.
- 13.
Andries CV, Degner DA, Ibrahim M. Identification of cutaneous arteries of the perineal and caudal thigh region: a cadaveric study in 12 cats. Vet Surg. 2020;49(2):304–309.
- 14.↑
Degner DA. Techniques to cover major perineal defects. Small animal cutaneous and body wall reconstruction. In: Proceedings of ACVS Surgery Summit. American College of Veterinary Surgeons; 2018.
- 15.↑
Avedillo L, Martín-Alguacil N, Salazar I. Anatomical variations of the blood vascular system in veterinary medicine: the internal iliac artery of the dog: part one. Anat Histol Embryol. 2015;44(4):299–307.
- 16.↑
Reetz JA, Seiler G, Mayhew PD, Holt DE. Ultrasonographic and color-flow Doppler ultrasonographic assessment of direct cutaneous arteries used for axial pattern skin flaps in dogs. J Am Vet Med Assoc. 2006;228(9):1361–1365.
- 17.↑
Rozen WM, Ting JW, Grinsell D, Ashton MW. Superior and inferior gluteal artery perforators: in-vivo anatomical study and planning for breast reconstruction. J Plast Reconstr Aesthet Surg. 2011;64(2):217–225.
- 18.↑
Tuinder SMH, Beugels J, Lataster A, et al. The lateral thigh perforator flap for autologous breast reconstruction: a prospective analysis of 138 flaps. Plast Reconstr Surg. 2018;141(2):257–268. doi:10.1097/PRS.0000000000004072
- 19.↑
Song WC, Bae SM, Han SH, Koh KS. Anatomical and radiological study of the superior and inferior gluteal arteries in the gluteus maximus muscle for musculocutaneous flap in Koreans. J Plast Reconstr Aesthet Surg. 2006;59(9):935–941.
