Favorable long-term functional outcome following left-sided compartmental epaxial muscle resection (T13-L7) for a longissimus lumborum liposarcoma in a dog: a case report

Favorable long-term functional outcome following left-sided compartmental epaxial muscle resection (T13-L7) for a longissimus lumborum liposarcoma in a dog: a case report | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Favorable long-term functional outcome following left-sided compartmental epaxial muscle resection (T13-L7) for a longissimus lumborum liposarcoma in a dog: a case report Joseph O Sullivan, Alan Wolfe, Marie-Pauline Maurin This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9534828/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background Liposarcomas are uncommon malignant soft tissue sarcomas in dogs and intramuscular liposarcomas involving the epaxial musculature are rare. Due to their locally invasive nature, wide excision is recommended however, the functional outcome following extensive epaxial muscle resection in dogs has not been documented. Case presentation A 10-year-old male-neutered Border Collie presented with a large, slowly progressive left dorsal lumbar swelling. Computed tomography identified a heterogeneous intramuscular mass within the left longissimus lumborum muscle extending from L1 to L6, with no evidence of metastatic disease. Cytology was consistent with liposarcoma. Curative-intent surgery was performed via unilateral compartmental excision of the multifidus, longissimus lumborum, and iliocostalis lumborum muscles. Significant hemorrhage and transient hypotension required blood transfusion and intensive care. Histopathology confirmed a well-differentiated liposarcoma. Transient hindlimb weakness and compensatory scoliosis was identified during postoperative recovery which improved over time. The dog returned to normal activity with no evidence of local recurrence at 16-month follow-up. Conclusions: This case suggests that extensive unilateral lumbar epaxial muscle resection can result in acceptable perioperative morbidity and excellent long-term functional outcome. Compartmental excision may represent a viable treatment option for selected paraspinal soft tissue sarcomas, supporting good quality of life despite substantial muscle loss. Liposarcoma Epaxial Muscle Compartmental Excision Case-Report Dog Figures Figure 1 Figure 2 Figure 3 Background Liposarcomas are uncommon malignant tumors in dogs. They are typically found in subcutaneous locations along the ventrum and extremities but can occur in other organs such as the spleen and bone [1] . They belong to the category of soft tissue sarcomas (STS) and similarly, tend to be locally invasive with low incidence of distant metastasis. Curative intent involves wide resection, typically regarded as 2–3 cm lateral margins and one unaffected fascial plane deep [2] . As with other STSs, the extent of surgical resection significantly impacts survival in canine liposarcomas. Median survival times are longest with wide resection (1188 days), compared to marginal resection (649 days) and incisional biopsy (183 days) [3] , supporting a favorable prognosis when adequate surgical management is achieved. Tumors affecting paraspinal musculature may not be amenable to wide resection, and morbidity associated with resection of the thoracolumbar epaxial muscles is unknown. This group of muscles includes the iliocostalis, longissimus (being the largest of the group) and transversospinalis (multifidis) muscles [4] . They contribute to propulsion through the coordinated action of the trunk and the limbs, but also act to dynamically stabilize the trunk against passive movements induced by gravitational and inertial forces. They are mainly inserted on the vertebral processes and as a result also contribute to spinal stability [4, 5] . To the authors’ knowledge, no functional outcomes associated with extensive epaxial resection have been reported. The purpose of this report is to describe the favorable outcome associated with extensive unilateral compartmental resection of the epaxial musculature from T13–L7 for the treatment of a liposarcoma affecting the longissimus lumborum muscle. Case Description A 10-year-old, 22.8kg male-neutered Border Collie was referred for investigation of a large, subcutaneous, left-dorsal lumbar mass. The dog had a known diagnosis of hypoadrenocorticism (Addison’s disease), which was reportedly well-controlled. On physical examination, a large, firm, non-painful subcutaneous mass measuring 14x7x7cm was palpated in the dorsal lumbar region, cranial to the wing of the ileum. Serum biochemistry revealed marked elevations in alkaline phosphatase (962 U/L; reference interval [RI] < 82), alanine aminotransferase (111 U/L; RI 0–36), and glutamate dehydrogenase (44 U/L; RI < 16), as well as hypertriglyceridemia (3.06 mmol/L; RI 0.11–1.69) and hypercholesterolemia (7.74 mmol/L; RI 3.2–6.5) likely secondary to corticosteroid administration. Informed owner consent was obtained prior to interventions. Thoracic and abdominal contrast-enhanced computed tomography (CT) revealed a well-defined left dorsal lumbar mass (14 cm x 6.7 cm x 6.4 cm), affecting the longissimus lumborum muscle, extending from L1 to L6 (Fig. 1 ). The mass was heterogeneous, displaying mostly fat, but also soft tissue, attenuation with mild contrast enhancement. Centrally, there was a relatively well-defined area of soft tissue attenuation, with moderate enhancement and enhancing rim. Peripherally, small mineral foci were present. The mass mildly compressed the left multifidus muscle medially and displaced the iliocostalis lumborum muscle ventrolaterally. No evident bony lysis or vertebral invasion was observed. No metastatic disease was identified. Fine-needle aspiration revealed high cellularity. Adipocytes demonstrated extreme anisokaryosis, karyomegaly, bizarre nuclear morphology, and abnormal nucleolar variation (Fig. 3 A) These findings were consistent with liposarcoma and surgical excision with curative intent was elected. Premedication with methadone 0.3mg/kg (Synthadon 10mg/ml; Animalcare Ltd., UK), ketamine 2mg/kg (Ketamidor 100mg/ml; Chanelle Pharma, Ireland), and dexmedetomidine (sedadex 0.5mg/ml, Dechra Veterinary Products, UK) was administered. Anesthesia was induced with propofol (Propofol Lipuro, B. Braun Melsungen AG) and maintained with sevoflurane (sevoflo 100%, Zoetis, Belgium) in oxygen. Skin incision was made in the left dorsal lumbar region, directly over the mass. A compartmental resection (multifidus, longissimus lumborum, and iliocostalis lumborum) from T13 to L7 was performed achieving 2cm cranial and caudal margins (Fig. 2 A-B). The multifidus muscles were elevated from their origins (mamillary processes) and insertions (spinous processes) using periosteal elevators and diathermy. Similarly, the longissimus and iliocostalis were elevated from the accessory and transverse processes, resected caudally at insertions on the iliac crest and medial ileum and cranially from the 12th /13th rib. Intraoperative hemorrhage from lumbar spinal arterial branches, as they exited each neuroforamen was controlled using diathermy. Acute blood loss with associated tachycardia and persistent hypotension (Mean Arterial Pressure 40-50mmHg) necessitated packed red blood cell transfusion. The resected epaxial muscle with mass in situ was submitted for histopathological assessment (Fig. 3 B). Deep muscle (shave) samples were also taken medially (interspinalis mm.), ventrally (intertransversarii mm.), cranially (longissimus thoracis mm.) and caudally (medial ileum) and submitted to assess for the presence of any neoplastic cells. The external abdominal oblique was utilized for closure and sutured to the interspinous ligament. An active drain and wound soak catheter were placed (Fig. 2 C). The incision was closed routinely without tension. Supported walks were required for 48 hours due to non-ambulatory left hindlimb paresis without proprioceptive deficit (Supplementary Video 1). Gradual improvement in comfort and mobility was observed and the patient was ambulatory, without assistance, 72 hours following surgery (Supplementary Video 2). Multimodal analgesia provided included 0.1mg/kg morphine/ 1mg/kg bupivacaine epidural (morphine sulphate 10mg/ml, Mercury Pharmaceuticals (Ireland) Ltd, bupivacaine hydrochloride 0.25%w/v, Mercury Pharmaceuticals (Ireland) Ltd), paracetamol (10mg/kg IV TID, B. Braun Melsungen AG), fentanyl (2-7ug/kg/hr, 50ug/ml Mercury Pharmaceuticals (Ireland) Ltd), ketamine CRI (5-10ug/kg/min, Ketamidor 100mg/ml; Chanelle Pharma, Ireland) gabapentin (10mg/kg PO TID, Neurontin 100mg, Upjohn EESV), and local anesthetic wound infusion (bupivacaine 1mg/kg QID), tapered as appropriate. Active drain and wound soak catheters were removed 4 days following surgery, and the patient was discharged 5 days postoperatively with paracetamol (250mg PO BID, Paratabs 500mg, Pinewood Laboratories Ltd), Gabapentin (200mg PO BID, Neurontin 100mg, Upjohn EESV) amoxicillin clavulanate (500mg PO BID, Noroclav 250mg, Norbrook Laboratories Ltd). At the time of discharge, the patient was comfortable, ambulatory, and systemically stable. Histopathology was consistent with a well-differentiated liposarcoma [6] (Fig. 3 C-D), composed of round to polygonal cells arranged in solid sheets with scant fibrovascular stroma. Neoplastic cells had a moderate to large amount of cytoplasm containing variable amounts of clear space (lipid) arranged in variably-sized distinct vacuoles. Nuclei varied from round to oval to irregular with speckled chromatin. One to two prominent deeply eosinophilic nucleoli were common. The mitotic count was less than 1 per 2.37mm 2 . Neoplastic cells were present at the medial and lateral margins. Cranial and caudal margins were clear. No neoplastic cells were observed in submitted shave margins. Neoplastic cells extended to the lateral margin bounded by lumbodorsal fascia, representing a robust fascial plane. Adjuvant chemotherapy was discussed with the owners, but declined in favor of local monitoring for recurrence. Excellent comfort levels were observed at two-week post-operative review, the patient was receiving no analgesia at this time and no wound complications encountered. There was visual indentation and deformity of the left dorsal lumbar region with associated significant right convex scoliosis (Fig. 2 D). Mild, persistent left hindlimb weakness was identified with no proprioceptive deficits. Continued controlled lead exercise was advised with incremental increased activity. No formal physiotherapy was undertaken. Return to normal exercise was initiated eight weeks following surgery, however persistent, mild left-hindlimb weakness was reported up to six months post-operatively. Long-term follow up provided by phone-call with the owner, physical examination at the referring veterinary surgeon and video gait analysis showed return to normal exercise and activity levels with no evident lameness or weakness (Supplemental video 3). Mild, but improved right convex scoliosis persisted. No long-term analgesia or physical therapy was necessary. No gross recurrence was observed on physical examination 16 months following surgery. The owner indicated they would make the same treatment decision again under similar circumstances. Discussion This case highlights a favorable outcome following extensive unilateral lumbar epaxial muscle resection and, to our knowledge, represents the first reported outcome of such a resection. Appropriate surgical dose and associated patient morbidity is paramount to decision-making in surgical oncology cases and treatment of STSs with unplanned surgeries can result in inferior outcomes [7,8] . There remains a paucity of literature on surgical outcomes associated with certain muscle resections in dogs, and reporting of this case aims to aid future decision making in our patients. A high suspicion of liposarcoma can be afforded preoperatively, differentiating them from other STSs based on cytological characteristics and staining (Oil Red O) [9] and from other lipomatous tumors by contrast CT findings [10,11] . Investigations in our case were highly suggestive of liposarcoma, with lipocytes displaying marked cytological atypia and malignant characteristics, without staining, and CT findings of a contrast-enhancing, heterogeneous mass with mixed fat/soft-tissue attenuation and mild amorphous mineralization. In the largest study on liposarcomas in dogs [3] , tumors were evenly distributed subcutaneously between axial and appendicular regions, with a minority present in viscera and one within bone marrow. Intramuscular locations are uncommonly reported with only three case reports previously published and these only had limited descriptions of surgical management and outcomes [12–14] . Given the typical CT features, cytological findings and history of a slow-growing mass, a surgical plan for a low-intermediate grade STS removal was performed. In the human literature, Enneking (1980) proposed compartmental excisions [15] , aimed at performing more conservative resections for lower-grade STSs, affording comparable outcomes and reduced morbidity and indeed, positive functional outcomes and local tumor control have been reported in a number of cases of STSs confined to single muscle bellies, remaining an alternative to wider surgical excision in select cases [16]. Dorsal and lateral to the longissimus mm., the thoracolumbar fascia represents a type I discrete fascial sheet as defined by Schroeder and Skinner [17] ; however, medially and ventrally it inserts at the base of the spinous processes and gives off deep segments to the intertransversarii mm. The multifidus mm. lies ventromedial to the longissimus mm., again with no defined border, aponeurosis or fascial division. Traditional wide excision was not elected due to the morbidity required such as skin reconstructive techniques and periosteal stripping/vertebrectomy, thus a skin-sparing, compartmental approach was pursued. At surgery, visual containment of the tumor within the muscle compartment was considered to be complete with our proposed compartmental excision. However close medial margins were suspected due to lack of a defined medial border. Therefore, shave samples were taken medially (interspinalis mm.), ventrally (intertransversarii mm.), cranially (longissimus thoracis mm.) and caudally (medial ileum), representing the intraoperatively considered narrowest margins. Targeted submission of shave margins from regions of concern has been shown to predict residual disease with intraoperative assessment reducing residual disease rates in human cancer patients [2] . Histologically, compartment margins contained neoplastic cells, whereas shave margins were clear. The incomplete compartment margins seen histologically in this case may potentially have been due to collection or processing artifact with separation of muscle fibers resulting in the presentation of a false margin for histological assessment. Alternatively, even with incomplete excision of low-intermediate grade STSs, recurrence is not absolute, and although recurrence rates are greater in cases of incompletely excised STSs [18] , no recurrence was reported in up to 66% of incompletely excised STSs. In this case, no gross recurrence was observed at 16 months postoperatively. The canine lumbar spine relies on coordinated activation of the epaxial, hypaxial, and abdominal musculature to provide dynamic stabilization during locomotion and postural control [4,19,20] . The epaxial musculature contributes to spinal movement and stabilization across all anatomical planes; varying according to gait and vertebral level [4] , with the m. longissimus dorsi and m. iliocostalis lumborum estimated to augment hindlimb muscle power by 12% in greyhounds [19] . It is unclear how removal of a large portion of active spinal stabilizers would affect a patient and whether instability could lead to mobility limitations, spinal pain, disc degeneration or other degenerative changes. On long-term follow-up no such issues were observed in this patient apart from obvious right convex scoliosis, which improved subjectively with time. Advanced imaging, objective kinematic gait and force plate analysis would be necessary to further categorize and determine possible long-term ill-effects. Although based on a single case report, unilateral lumbar epaxial muscle resection resulted in acceptable post-operative morbidity and a return to normal daily function and quality of life. This should help guide the decision-making process when considering surgical oncology cases in this region. Further research is warranted to evaluate for long-term ill-effects of epaxial muscle resection. Abbreviations STS – Soft Tissue Sarcoma CT – Computed Tomography CRI – Continuous Rate Infusion TID – Three times daily QID – Four times daily BID – Twice daily Declarations Acknowledgements: Not applicable Funding: Not Applicable Authors and Affiliations: Section of Small Animal Clinical Studies, Department of Small Animal Surgery, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland D04 W6F6. Joseph O Sullivan, Marie-Pauline Maurin Department of Pathobiology, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland D04 W6F6. Alan Wolfe Author Contributions (CRediT): J. O’Sullivan: Conceptualization, Data curation, Writing – original draft, Writing – review & editing, Final approval; M.-P. Maurin: Conceptualization, Writing – review & editing, Final approval; A. Wolfe: Data curation, Writing – review & editing, Final approval. Corresponding Author: Joseph O’ Sullivan MVB PgCertSAM Section of Small Animal Clinical Studies, Department of Small Animal Surgery, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland D04 W6F6. Email: [email protected] ORCID: https://orcid.org/0000-0001-7134-938X Ethics declarations Ethics approval and consent to participate The dog reported in this study was a client-owned companion animal with naturally occurring cancer. Informed consent was obtained from the client to treat their pet with the reported strategy. The dog was treated according to the principles and practices of specialty medicine prevailing at the time of their treatment. Consent for publication Not applicable. Competing interests The authors declare no conflict of interest. Data availability statement: Any information pertaining to this case report is available from the corresponding author upon reasonable request. References MacEwen EG, Powers BE, Macy D, et al. Soft tissue sarcomas. In: Withrow SJ, Vail DM, Page RL, editors. Small Animal Clinical Oncology. 5th ed. St. Louis (MO): Elsevier; 2013. p. 356–380. Bray JP. Soft tissue sarcoma in the dog – part 1: a current review. J Small Anim Pract. 2016;57(10):510–519. Baez JL, Hendrick MJ, Shofer FS, Goldkamp C, Sorenmo KU. Liposarcomas in dogs: 56 cases (1989–2000). J Am Vet Med Assoc. 2004;224(6):887–891. Evans HE, de Lahunta A, Hermanson JW. Miller’s Anatomy of the Dog. 5th ed. St. Louis (MO): Elsevier; 2019. Chapter 6, The muscular system. Schilling N, Carrier DR. Function of the epaxial muscles in walking, trotting and galloping dogs: implications for the evolution of epaxial muscle function in tetrapods. J Exp Biol. 2010;213:1490–1502. Roccabianca P, Schulman FY, Avallone G, Foster RA, Scruggs JL, Dittmer K, Kiupel M. Surgical pathology of tumors of domestic animals. Volume 3: Tumors of soft tissue. Gurnee (IL): Davis-Thompson DVM Foundation; 2020. Kollender R, Merimsky O, Sternheim A, Gortzak Y, Dadia S, Doron A, et al. Radiation therapy before repeat wide resection for unplanned surgery of soft tissue sarcoma (“oops” operation) results in improved disease-free survival. Adv Radiat Oncol. 2022;7:101007. Bray JP, Polton GA, McSporran KD, Bridges J, Whitbread TM. Canine soft tissue sarcoma managed in first opinion practice: outcome in 350 cases. Vet Surg. 2014;43(7):774–782. Masserdotti C, Bonfanti U, De Lorenzi D, Ottolini N. Use of Oil Red O stain in the cytologic diagnosis of canine liposarcoma. Vet Clin Pathol. 2006;35(1):37–41. Spoldi E, Schwarz T, Sabattini S, Vignoli M, Cancedda S, Rossi F. Comparisons among computed tomographic features of adipose masses in dogs and cats. Vet Radiol Ultrasound. 2017;58(1):29–37. Fuerst JA, Reichle JK, Szabo D, Cohen EB, Biller DS, Goggin JM, et al. Computed tomographic findings in 24 dogs with liposarcoma. Vet Radiol Ultrasound. 2017;58(1):23–28. Green KT, Regazoli E, Olegário da Silva E, Scortecci Hilst CL, Wingeter Di Santis G. Myxoid liposarcoma in a dog. Online J Vet Res. 2013;17(5):218–226. Castro JLC, Santalucia S, Paiva Castro VS, Pires MVM, Suzano SMC, Leme Júnior PTO, et al. Liposarcoma with perineal hernia in dog. Rev Bras Cienc Vet. 2014;21(3):163–166. Jeong J, Chang J, Lee S, An S, Kim K, Lee MS, Yhee JY, Kim J, Eom K. Computed tomographic findings of diaphragmatic well-differentiated liposarcoma in a dog. Vet Radiol Ultrasound. 2025;66:e70082. Enneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res. 1980;(153):106–120. Olimpo M, Buracco P, Ferraris EI, Piras LA, Maniscalco L, Giacobino D, et al. Surgical excision of intramuscular sarcomas: description of three cases in dogs. Animals (Basel). 2023;13(2):218. Schroeder MM, Skinner OT. Fascial plane mapping for superficial tumor resection in dogs. Part I: Neck and trunk. Vet Surg. 2022;51(1):68–78. Milovancev M, Tuohy JL, Townsend KL, Irvin VL. Influence of surgical margin completeness on risk of local tumour recurrence in canine cutaneous and subcutaneous soft tissue sarcoma: a systematic review and meta-analysis. Vet Comp Oncol. 2019;17(3):354–364. Webster EL, Hudson PE, Channon SB. Comparative functional anatomy of the epaxial musculature of dogs (Canis familiaris) bred for sprinting vs. fighting. J Anat. 2014;225(3):317–327. Ritter DA, Nassar PN, Fife MM, Carrier DR. Epaxial muscle function in trotting dogs. J Exp Biol. 2001;204:3053–3064. Additional Declarations No competing interests reported. Supplementary Files 16monthsPostOpSubmission.mov Day1PostOperatively.mp4 Day4PostOperatively.mp4 Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 11 May, 2026 Reviewers agreed at journal 29 Apr, 2026 Reviewers invited by journal 29 Apr, 2026 Editor assigned by journal 27 Apr, 2026 Submission checks completed at journal 27 Apr, 2026 First submitted to journal 26 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9534828","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":636338516,"identity":"dc3d4dc0-f6a8-4b1f-96b5-fe995048489a","order_by":0,"name":"Joseph O Sullivan","email":"data:image/png;base64,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","orcid":"","institution":"University College Dublin","correspondingAuthor":true,"prefix":"","firstName":"Joseph","middleName":"O","lastName":"Sullivan","suffix":""},{"id":636338520,"identity":"1d6413f6-7d53-45e8-8477-c65e04eba822","order_by":1,"name":"Alan Wolfe","email":"","orcid":"","institution":"University College Dublin","correspondingAuthor":false,"prefix":"","firstName":"Alan","middleName":"","lastName":"Wolfe","suffix":""},{"id":636338521,"identity":"d9b9b76d-991f-412b-8a25-f82b26a827af","order_by":2,"name":"Marie-Pauline Maurin","email":"","orcid":"","institution":"University College Dublin","correspondingAuthor":false,"prefix":"","firstName":"Marie-Pauline","middleName":"","lastName":"Maurin","suffix":""}],"badges":[],"createdAt":"2026-04-26 23:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9534828/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9534828/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108947432,"identity":"28ab46bb-40d9-4b3b-9125-0cbc61174790","added_by":"auto","created_at":"2026-05-11 06:28:56","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1402499,"visible":true,"origin":"","legend":"\u003cp\u003eCT Multiplanar reconstruction (pre-contrast) of expansile, heterogenous mass (14 cm in craniocaudal measurement, 6.7 cm mediolateral and 6.4 cm dorsoventral) within the longissimus lumborum muscle causing ventrolateral displacement of the Ileocostalis lumborum (A). Transverse (A), Sagittal (B) and Dorsal (C) reconstructions.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/01ae05d3209e4e01b341a63a.jpg"},{"id":108947462,"identity":"6fa1d935-1628-45cc-9894-c4a42f3321d5","added_by":"auto","created_at":"2026-05-11 06:29:13","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":7109852,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative photographs showing (A) enbloc resection of epaxial muscles from cranial to caudal, (B) appearance of vertebral column after resection with 12th and 13th left rib visible (asterisks), exposed left side of dorsal spinous processes, vertebral bodies, facet joints and dorsal surface of transverse processes with intertransversarii muscles, craniodorsal aspect of left iliac crest (star), (C) elevation of external abdominal oblique muscle and sutured to the interspinous ligaments and (D) patient 14 days post-operatively, when presenting for staple removal with evident right convex scoliosis\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/3e2b0c8078b157f657bd1ed4.jpg"},{"id":108947456,"identity":"6e0f72f3-5e6c-459d-95ab-8a120e5877c2","added_by":"auto","created_at":"2026-05-11 06:29:07","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1596151,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Cytology of left lumbar epaxial mass (modified Wright-Giemsa stain) showing frequent large clumps of adipose tissue with numerous adipocytes. Cells display extreme karyomegaly and anisokaryosis with occasional extreme enlargement and variation of nucleolar size. Nuclear-to-cytoplasmic area ratio is much reduced in many cells. Nuclear and nucleolar shape are abnormal and often bizarre. (B) Gross pathology specimen showing pale, firm fatty tumour with necrotic core (liposarcoma) within longissimus lumborum muscle bell. (C) and (D) Histopathological assessment of mass (Haematoxylin and eosin (H\u0026amp;E), X100 magnification (C) X400 magnification (D), with 100um scale bars), identified round to polygonal cells arranged in solid sheets with scant fibrovascular stroma. Neoplastic cells had a moderate to large amount of cytoplasm containing variable amounts of clear space (lipid) arranged in variably-sized distinct vacuoles. Nuclei varied from round to oval to irregular with speckled chromatin. One to two prominent deeply eosinophilic nucleoli were common. The mitotic count was less than 1 per 2.37mm2.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/b1df1ab4d351ffd1fbdf5d1e.jpg"},{"id":108978105,"identity":"444ebc9a-4ac0-4f92-8249-3a2615cab49e","added_by":"auto","created_at":"2026-05-11 11:34:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":13644459,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/e5b60104-42d0-41a1-93b6-ede89dc8b76a.pdf"},{"id":108947503,"identity":"149ab751-9e76-4030-a8ce-b23c90158b30","added_by":"auto","created_at":"2026-05-11 06:29:32","extension":"mov","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":34978060,"visible":true,"origin":"","legend":"","description":"","filename":"16monthsPostOpSubmission.mov","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/95b9708a817f7581d7aef9f9.mov"},{"id":108947461,"identity":"563c16d4-4459-4e78-afeb-8e8152d1a6ee","added_by":"auto","created_at":"2026-05-11 06:29:12","extension":"mp4","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":65762101,"visible":true,"origin":"","legend":"","description":"","filename":"Day1PostOperatively.mp4","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/98dc27c8ed45ee11756e09c8.mp4"},{"id":108947563,"identity":"255fc3f1-92a5-4845-8f8a-a229988b5cf7","added_by":"auto","created_at":"2026-05-11 06:29:39","extension":"mp4","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":84939993,"visible":true,"origin":"","legend":"","description":"","filename":"Day4PostOperatively.mp4","url":"https://assets-eu.researchsquare.com/files/rs-9534828/v1/682e189fc5c09c11f1cf4f40.mp4"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eFavorable long-term functional outcome following left-sided compartmental epaxial muscle resection (T13-L7) for a longissimus lumborum liposarcoma in a dog: a case report\u003c/p\u003e","fulltext":[{"header":"Background","content":"\u003cp\u003eLiposarcomas are uncommon malignant tumors in dogs. They are typically found in subcutaneous locations along the ventrum and extremities but can occur in other organs such as the spleen and bone \u003cb\u003e[1]\u003c/b\u003e. They belong to the category of soft tissue sarcomas (STS) and similarly, tend to be locally invasive with low incidence of distant metastasis. Curative intent involves wide resection, typically regarded as 2\u0026ndash;3 cm lateral margins and one unaffected fascial plane deep \u003cb\u003e[2]\u003c/b\u003e. As with other STSs, the extent of surgical resection significantly impacts survival in canine liposarcomas. Median survival times are longest with wide resection (1188 days), compared to marginal resection (649 days) and incisional biopsy (183 days) \u003cb\u003e[3]\u003c/b\u003e, supporting a favorable prognosis when adequate surgical management is achieved.\u003c/p\u003e \u003cp\u003eTumors affecting paraspinal musculature may not be amenable to wide resection, and morbidity associated with resection of the thoracolumbar epaxial muscles is unknown. This group of muscles includes the iliocostalis, longissimus (being the largest of the group) and transversospinalis (multifidis) muscles \u003cb\u003e[4]\u003c/b\u003e. They contribute to propulsion through the coordinated action of the trunk and the limbs, but also act to dynamically stabilize the trunk against passive movements induced by gravitational and inertial forces. They are mainly inserted on the vertebral processes and as a result also contribute to spinal stability \u003cb\u003e[4, 5]\u003c/b\u003e. To the authors\u0026rsquo; knowledge, no functional outcomes associated with extensive epaxial resection have been reported.\u003c/p\u003e \u003cp\u003eThe purpose of this report is to describe the favorable outcome associated with extensive unilateral compartmental resection of the epaxial musculature from T13\u0026ndash;L7 for the treatment of a liposarcoma affecting the longissimus lumborum muscle.\u003c/p\u003e"},{"header":"Case Description","content":"\u003cp\u003eA 10-year-old, 22.8kg male-neutered Border Collie was referred for investigation of a large, subcutaneous, left-dorsal lumbar mass. The dog had a known diagnosis of hypoadrenocorticism (Addison\u0026rsquo;s disease), which was reportedly well-controlled.\u003c/p\u003e \u003cp\u003eOn physical examination, a large, firm, non-painful subcutaneous mass measuring 14x7x7cm was palpated in the dorsal lumbar region, cranial to the wing of the ileum. Serum biochemistry revealed marked elevations in alkaline phosphatase (962 U/L; reference interval [RI]\u0026thinsp;\u0026lt;\u0026thinsp;82), alanine aminotransferase (111 U/L; RI 0\u0026ndash;36), and glutamate dehydrogenase (44 U/L; RI\u0026thinsp;\u0026lt;\u0026thinsp;16), as well as hypertriglyceridemia (3.06 mmol/L; RI 0.11\u0026ndash;1.69) and hypercholesterolemia (7.74 mmol/L; RI 3.2\u0026ndash;6.5) likely secondary to corticosteroid administration. Informed owner consent was obtained prior to interventions.\u003c/p\u003e \u003cp\u003eThoracic and abdominal contrast-enhanced computed tomography (CT) revealed a well-defined left dorsal lumbar mass (14 cm x 6.7 cm x 6.4 cm), affecting the longissimus lumborum muscle, extending from L1 to L6 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The mass was heterogeneous, displaying mostly fat, but also soft tissue, attenuation with mild contrast enhancement. Centrally, there was a relatively well-defined area of soft tissue attenuation, with moderate enhancement and enhancing rim. Peripherally, small mineral foci were present. The mass mildly compressed the left multifidus muscle medially and displaced the iliocostalis lumborum muscle ventrolaterally. No evident bony lysis or vertebral invasion was observed. No metastatic disease was identified. Fine-needle aspiration revealed high cellularity. Adipocytes demonstrated extreme anisokaryosis, karyomegaly, bizarre nuclear morphology, and abnormal nucleolar variation (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eA) These findings were consistent with liposarcoma and surgical excision with curative intent was elected.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePremedication with methadone 0.3mg/kg (Synthadon 10mg/ml; Animalcare Ltd., UK), ketamine 2mg/kg (Ketamidor 100mg/ml; Chanelle Pharma, Ireland), and dexmedetomidine (sedadex 0.5mg/ml, Dechra Veterinary Products, UK) was administered. Anesthesia was induced with propofol (Propofol Lipuro, B. Braun Melsungen AG) and maintained with sevoflurane (sevoflo 100%, Zoetis, Belgium) in oxygen. Skin incision was made in the left dorsal lumbar region, directly over the mass. A compartmental resection (multifidus, longissimus lumborum, and iliocostalis lumborum) from T13 to L7 was performed achieving 2cm cranial and caudal margins (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eA-B). The multifidus muscles were elevated from their origins (mamillary processes) and insertions (spinous processes) using periosteal elevators and diathermy. Similarly, the longissimus and iliocostalis were elevated from the accessory and transverse processes, resected caudally at insertions on the iliac crest and medial ileum and cranially from the 12th /13th rib. Intraoperative hemorrhage from lumbar spinal arterial branches, as they exited each neuroforamen was controlled using diathermy. Acute blood loss with associated tachycardia and persistent hypotension (Mean Arterial Pressure 40-50mmHg) necessitated packed red blood cell transfusion. The resected epaxial muscle with mass in situ was submitted for histopathological assessment (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eB). Deep muscle (shave) samples were also taken medially (interspinalis mm.), ventrally (intertransversarii mm.), cranially (longissimus thoracis mm.) and caudally (medial ileum) and submitted to assess for the presence of any neoplastic cells. The external abdominal oblique was utilized for closure and sutured to the interspinous ligament. An active drain and wound soak catheter were placed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). The incision was closed routinely without tension.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSupported walks were required for 48 hours due to non-ambulatory left hindlimb paresis without proprioceptive deficit (Supplementary Video 1). Gradual improvement in comfort and mobility was observed and the patient was ambulatory, without assistance, 72 hours following surgery (Supplementary Video 2). Multimodal analgesia provided included 0.1mg/kg morphine/ 1mg/kg bupivacaine epidural (morphine sulphate 10mg/ml, Mercury Pharmaceuticals (Ireland) Ltd, bupivacaine hydrochloride 0.25%w/v, Mercury Pharmaceuticals (Ireland) Ltd), paracetamol (10mg/kg IV TID, B. Braun Melsungen AG), fentanyl (2-7ug/kg/hr, 50ug/ml Mercury Pharmaceuticals (Ireland) Ltd), ketamine CRI (5-10ug/kg/min, Ketamidor 100mg/ml; Chanelle Pharma, Ireland) gabapentin (10mg/kg PO TID, Neurontin 100mg, Upjohn EESV), and local anesthetic wound infusion (bupivacaine 1mg/kg QID), tapered as appropriate.\u003c/p\u003e \u003cp\u003eActive drain and wound soak catheters were removed 4 days following surgery, and the patient was discharged 5 days postoperatively with paracetamol (250mg PO BID, Paratabs 500mg, Pinewood Laboratories Ltd), Gabapentin (200mg PO BID, Neurontin 100mg, Upjohn EESV) amoxicillin clavulanate (500mg PO BID, Noroclav 250mg, Norbrook Laboratories Ltd). At the time of discharge, the patient was comfortable, ambulatory, and systemically stable.\u003c/p\u003e \u003cp\u003eHistopathology was consistent with a well-differentiated liposarcoma \u003cb\u003e[6]\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eC-D), composed of round to polygonal cells arranged in solid sheets with scant fibrovascular stroma. Neoplastic cells had a moderate to large amount of cytoplasm containing variable amounts of clear space (lipid) arranged in variably-sized distinct vacuoles. Nuclei varied from round to oval to irregular with speckled chromatin. One to two prominent deeply eosinophilic nucleoli were common. The mitotic count was less than 1 per 2.37mm\u003csup\u003e2\u003c/sup\u003e. Neoplastic cells were present at the medial and lateral margins. Cranial and caudal margins were clear. No neoplastic cells were observed in submitted shave margins. Neoplastic cells extended to the lateral margin bounded by lumbodorsal fascia, representing a robust fascial plane. Adjuvant chemotherapy was discussed with the owners, but declined in favor of local monitoring for recurrence.\u003c/p\u003e \u003cp\u003eExcellent comfort levels were observed at two-week post-operative review, the patient was receiving no analgesia at this time and no wound complications encountered. There was visual indentation and deformity of the left dorsal lumbar region with associated significant right convex scoliosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eD). Mild, persistent left hindlimb weakness was identified with no proprioceptive deficits. Continued controlled lead exercise was advised with incremental increased activity. No formal physiotherapy was undertaken. Return to normal exercise was initiated eight weeks following surgery, however persistent, mild left-hindlimb weakness was reported up to six months post-operatively. Long-term follow up provided by phone-call with the owner, physical examination at the referring veterinary surgeon and video gait analysis showed return to normal exercise and activity levels with no evident lameness or weakness (Supplemental video 3). Mild, but improved right convex scoliosis persisted. No long-term analgesia or physical therapy was necessary. No gross recurrence was observed on physical examination 16 months following surgery. The owner indicated they would make the same treatment decision again under similar circumstances.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis case highlights a favorable outcome following extensive unilateral lumbar epaxial muscle resection and, to our knowledge, represents the first reported outcome of such a resection. Appropriate surgical dose and associated patient morbidity is paramount to decision-making in surgical oncology cases and treatment of STSs with unplanned surgeries can result in inferior outcomes \u003cb\u003e[7,8]\u003c/b\u003e. There remains a paucity of literature on surgical outcomes associated with certain muscle resections in dogs, and reporting of this case aims to aid future decision making in our patients.\u003c/p\u003e \u003cp\u003eA high suspicion of liposarcoma can be afforded preoperatively, differentiating them from other STSs based on cytological characteristics and staining (Oil Red O) \u003cb\u003e[9]\u003c/b\u003e and from other lipomatous tumors by contrast CT findings \u003cb\u003e[10,11]\u003c/b\u003e. Investigations in our case were highly suggestive of liposarcoma, with lipocytes displaying marked cytological atypia and malignant characteristics, without staining, and CT findings of a contrast-enhancing, heterogeneous mass with mixed fat/soft-tissue attenuation and mild amorphous mineralization. In the largest study on liposarcomas in dogs \u003cb\u003e[3]\u003c/b\u003e, tumors were evenly distributed subcutaneously between axial and appendicular regions, with a minority present in viscera and one within bone marrow. Intramuscular locations are uncommonly reported with only three case reports previously published and these only had limited descriptions of surgical management and outcomes \u003cb\u003e[12\u0026ndash;14]\u003c/b\u003e. Given the typical CT features, cytological findings and history of a slow-growing mass, a surgical plan for a low-intermediate grade STS removal was performed.\u003c/p\u003e \u003cp\u003eIn the human literature, Enneking (1980) proposed compartmental excisions \u003cb\u003e[15]\u003c/b\u003e, aimed at performing more conservative resections for lower-grade STSs, affording comparable outcomes and reduced morbidity and indeed, positive functional outcomes and local tumor control have been reported in a number of cases of STSs confined to single muscle bellies, remaining an alternative to wider surgical excision in select cases \u003cb\u003e[16].\u003c/b\u003e Dorsal and lateral to the longissimus mm., the thoracolumbar fascia represents a type I discrete fascial sheet as defined by Schroeder and Skinner \u003cb\u003e[17]\u003c/b\u003e; however, medially and ventrally it inserts at the base of the spinous processes and gives off deep segments to the intertransversarii mm. The multifidus mm. lies ventromedial to the longissimus mm., again with no defined border, aponeurosis or fascial division. Traditional wide excision was not elected due to the morbidity required such as skin reconstructive techniques and periosteal stripping/vertebrectomy, thus a skin-sparing, compartmental approach was pursued. At surgery, visual containment of the tumor within the muscle compartment was considered to be complete with our proposed compartmental excision. However close medial margins were suspected due to lack of a defined medial border. Therefore, shave samples were taken medially (interspinalis mm.), ventrally (intertransversarii mm.), cranially (longissimus thoracis mm.) and caudally (medial ileum), representing the intraoperatively considered narrowest margins. Targeted submission of shave margins from regions of concern has been shown to predict residual disease with intraoperative assessment reducing residual disease rates in human cancer patients \u003cb\u003e[2]\u003c/b\u003e. Histologically, compartment margins contained neoplastic cells, whereas shave margins were clear. The incomplete compartment margins seen histologically in this case may potentially have been due to collection or processing artifact with separation of muscle fibers resulting in the presentation of a false margin for histological assessment. Alternatively, even with incomplete excision of low-intermediate grade STSs, recurrence is not absolute, and although recurrence rates are greater in cases of incompletely excised STSs \u003cb\u003e[18]\u003c/b\u003e, no recurrence was reported in up to 66% of incompletely excised STSs. In this case, no gross recurrence was observed at 16 months postoperatively.\u003c/p\u003e \u003cp\u003eThe canine lumbar spine relies on coordinated activation of the epaxial, hypaxial, and abdominal musculature to provide dynamic stabilization during locomotion and postural control \u003cb\u003e[4,19,20]\u003c/b\u003e. The epaxial musculature contributes to spinal movement and stabilization across all anatomical planes; varying according to gait and vertebral level \u003cb\u003e[4]\u003c/b\u003e, with the m. longissimus dorsi and m. iliocostalis lumborum estimated to augment hindlimb muscle power by 12% in greyhounds \u003cb\u003e[19]\u003c/b\u003e. It is unclear how removal of a large portion of active spinal stabilizers would affect a patient and whether instability could lead to mobility limitations, spinal pain, disc degeneration or other degenerative changes. On long-term follow-up no such issues were observed in this patient apart from obvious right convex scoliosis, which improved subjectively with time. Advanced imaging, objective kinematic gait and force plate analysis would be necessary to further categorize and determine possible long-term ill-effects.\u003c/p\u003e \u003cp\u003eAlthough based on a single case report, unilateral lumbar epaxial muscle resection resulted in acceptable post-operative morbidity and a return to normal daily function and quality of life. This should help guide the decision-making process when considering surgical oncology cases in this region. Further research is warranted to evaluate for long-term ill-effects of epaxial muscle resection.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eSTS \u0026ndash;\u0026nbsp;\u003c/strong\u003eSoft Tissue Sarcoma\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCT \u0026ndash;\u003c/strong\u003e Computed Tomography\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCRI \u0026ndash;\u003c/strong\u003e Continuous Rate Infusion\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTID \u0026ndash;\u003c/strong\u003e Three times daily\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQID \u0026ndash;\u003c/strong\u003e Four times daily\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBID \u0026ndash;\u003c/strong\u003e Twice daily\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements: \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding: \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors and Affiliations:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSection of Small Animal Clinical Studies, Department of Small Animal Surgery, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland D04 W6F6. \u003c/p\u003e\n\u003cp\u003eJoseph O Sullivan, Marie-Pauline Maurin\u003c/p\u003e\n\u003cp\u003eDepartment of Pathobiology, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland D04 W6F6.\u003c/p\u003e\n\u003cp\u003eAlan Wolfe\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions (CRediT):\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJ. O\u0026rsquo;Sullivan: Conceptualization, Data curation, Writing \u0026ndash; original draft, Writing \u0026ndash; review \u0026amp; editing, Final approval; M.-P. Maurin: Conceptualization, Writing \u0026ndash; review \u0026amp; editing, Final approval; A. Wolfe: Data curation, Writing \u0026ndash; review \u0026amp; editing, Final approval.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding Author:\u003c/strong\u003e \u003c/p\u003e\n\u003cp\u003eJoseph O\u0026rsquo; Sullivan MVB PgCertSAM\u003c/p\u003e\n\u003cp\u003eSection of Small Animal Clinical Studies, Department of Small Animal Surgery, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland D04 W6F6.\u003c/p\u003e\n\u003cp\u003eEmail: [email protected] ORCID: https://orcid.org/0000-0001-7134-938X\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe dog reported in this study was a client-owned companion animal with naturally occurring cancer. Informed consent was obtained from the client to treat their pet with the reported strategy. The dog was treated according to the principles and practices of specialty medicine prevailing at the time of their treatment.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eData availability statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAny information pertaining to this case report is available from the corresponding author upon reasonable request.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eMacEwen EG, Powers BE, Macy D, et al. Soft tissue sarcomas. In: Withrow SJ, Vail DM, Page RL, editors. Small Animal Clinical Oncology. 5th ed. St. Louis (MO): Elsevier; 2013. p. 356\u0026ndash;380.\u003c/li\u003e\n \u003cli\u003eBray JP. Soft tissue sarcoma in the dog \u0026ndash; part 1: a current review. J Small Anim Pract. 2016;57(10):510\u0026ndash;519.\u003c/li\u003e\n \u003cli\u003eBaez JL, Hendrick MJ, Shofer FS, Goldkamp C, Sorenmo KU. Liposarcomas in dogs: 56 cases (1989\u0026ndash;2000). J Am Vet Med Assoc. 2004;224(6):887\u0026ndash;891.\u003c/li\u003e\n \u003cli\u003eEvans HE, de Lahunta A, Hermanson JW. Miller\u0026rsquo;s Anatomy of the Dog. 5th ed. St. Louis (MO): Elsevier; 2019. Chapter 6, The muscular system.\u003c/li\u003e\n \u003cli\u003eSchilling N, Carrier DR. Function of the epaxial muscles in walking, trotting and galloping dogs: implications for the evolution of epaxial muscle function in tetrapods. J Exp Biol. 2010;213:1490\u0026ndash;1502.\u003c/li\u003e\n \u003cli\u003eRoccabianca P, Schulman FY, Avallone G, Foster RA, Scruggs JL, Dittmer K, Kiupel M. Surgical pathology of tumors of domestic animals. Volume 3: Tumors of soft tissue. Gurnee (IL): Davis-Thompson DVM Foundation; 2020.\u003c/li\u003e\n \u003cli\u003eKollender R, Merimsky O, Sternheim A, Gortzak Y, Dadia S, Doron A, et al. Radiation therapy before repeat wide resection for unplanned surgery of soft tissue sarcoma (\u0026ldquo;oops\u0026rdquo; operation) results in improved disease-free survival. Adv Radiat Oncol. 2022;7:101007.\u003c/li\u003e\n \u003cli\u003eBray JP, Polton GA, McSporran KD, Bridges J, Whitbread TM. Canine soft tissue sarcoma managed in first opinion practice: outcome in 350 cases. Vet Surg. 2014;43(7):774\u0026ndash;782.\u003c/li\u003e\n \u003cli\u003eMasserdotti C, Bonfanti U, De Lorenzi D, Ottolini N. Use of Oil Red O stain in the cytologic diagnosis of canine liposarcoma. Vet Clin Pathol. 2006;35(1):37\u0026ndash;41.\u003c/li\u003e\n \u003cli\u003eSpoldi E, Schwarz T, Sabattini S, Vignoli M, Cancedda S, Rossi F. Comparisons among computed tomographic features of adipose masses in dogs and cats. Vet Radiol Ultrasound. 2017;58(1):29\u0026ndash;37.\u003c/li\u003e\n \u003cli\u003eFuerst JA, Reichle JK, Szabo D, Cohen EB, Biller DS, Goggin JM, et al. Computed tomographic findings in 24 dogs with liposarcoma. Vet Radiol Ultrasound. 2017;58(1):23\u0026ndash;28.\u003c/li\u003e\n \u003cli\u003eGreen KT, Regazoli E, Oleg\u0026aacute;rio da Silva E, Scortecci Hilst CL, Wingeter Di Santis G. Myxoid liposarcoma in a dog. Online J Vet Res. 2013;17(5):218\u0026ndash;226.\u003c/li\u003e\n \u003cli\u003eCastro JLC, Santalucia S, Paiva Castro VS, Pires MVM, Suzano SMC, Leme J\u0026uacute;nior PTO, et al. Liposarcoma with perineal hernia in dog. Rev Bras Cienc Vet. 2014;21(3):163\u0026ndash;166.\u003c/li\u003e\n \u003cli\u003eJeong J, Chang J, Lee S, An S, Kim K, Lee MS, Yhee JY, Kim J, Eom K. Computed tomographic findings of diaphragmatic well-differentiated liposarcoma in a dog. Vet Radiol Ultrasound. 2025;66:e70082.\u003c/li\u003e\n \u003cli\u003eEnneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res. 1980;(153):106\u0026ndash;120.\u003c/li\u003e\n \u003cli\u003eOlimpo M, Buracco P, Ferraris EI, Piras LA, Maniscalco L, Giacobino D, et al. Surgical excision of intramuscular sarcomas: description of three cases in dogs. Animals (Basel). 2023;13(2):218.\u003c/li\u003e\n \u003cli\u003eSchroeder MM, Skinner OT. Fascial plane mapping for superficial tumor resection in dogs. Part I: Neck and trunk. Vet Surg. 2022;51(1):68\u0026ndash;78.\u003c/li\u003e\n \u003cli\u003eMilovancev M, Tuohy JL, Townsend KL, Irvin VL. Influence of surgical margin completeness on risk of local tumour recurrence in canine cutaneous and subcutaneous soft tissue sarcoma: a systematic review and meta-analysis. Vet Comp Oncol. 2019;17(3):354\u0026ndash;364.\u003c/li\u003e\n \u003cli\u003eWebster EL, Hudson PE, Channon SB. Comparative functional anatomy of the epaxial musculature of dogs (Canis familiaris) bred for sprinting vs. fighting. J Anat. 2014;225(3):317\u0026ndash;327.\u003c/li\u003e\n \u003cli\u003eRitter DA, Nassar PN, Fife MM, Carrier DR. Epaxial muscle function in trotting dogs. J Exp Biol. 2001;204:3053\u0026ndash;3064.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"veterinary-oncology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Veterinary Oncology](https://veterinaryoncology.biomedcentral.com/)","snPcode":"44356","submissionUrl":"https://submission.springernature.com/new-submission/44356/3","title":"Veterinary Oncology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Liposarcoma, Epaxial Muscle, Compartmental Excision, Case-Report, Dog","lastPublishedDoi":"10.21203/rs.3.rs-9534828/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9534828/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eLiposarcomas are uncommon malignant soft tissue sarcomas in dogs and intramuscular liposarcomas involving the epaxial musculature are rare. Due to their locally invasive nature, wide excision is recommended however, the functional outcome following extensive epaxial muscle resection in dogs has not been documented.\u003c/p\u003e\u003ch2\u003eCase presentation\u003c/h2\u003e \u003cp\u003eA 10-year-old male-neutered Border Collie presented with a large, slowly progressive left dorsal lumbar swelling. Computed tomography identified a heterogeneous intramuscular mass within the left longissimus lumborum muscle extending from L1 to L6, with no evidence of metastatic disease. Cytology was consistent with liposarcoma. Curative-intent surgery was performed via unilateral compartmental excision of the multifidus, longissimus lumborum, and iliocostalis lumborum muscles. Significant hemorrhage and transient hypotension required blood transfusion and intensive care. Histopathology confirmed a well-differentiated liposarcoma. Transient hindlimb weakness and compensatory scoliosis was identified during postoperative recovery which improved over time. The dog returned to normal activity with no evidence of local recurrence at 16-month follow-up.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eThis case suggests that extensive unilateral lumbar epaxial muscle resection can result in acceptable perioperative morbidity and excellent long-term functional outcome. Compartmental excision may represent a viable treatment option for selected paraspinal soft tissue sarcomas, supporting good quality of life despite substantial muscle loss.\u003c/p\u003e","manuscriptTitle":"Favorable long-term functional outcome following left-sided compartmental epaxial muscle resection (T13-L7) for a longissimus lumborum liposarcoma in a dog: a case report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-11 06:27:33","doi":"10.21203/rs.3.rs-9534828/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"242131891160525008799353821848525870968","date":"2026-05-11T14:15:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"129907692707782816105388275990681420516","date":"2026-04-29T17:18:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-29T14:43:58+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-27T14:50:26+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-27T14:50:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Veterinary Oncology","date":"2026-04-26T23:22:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"veterinary-oncology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Veterinary Oncology](https://veterinaryoncology.biomedcentral.com/)","snPcode":"44356","submissionUrl":"https://submission.springernature.com/new-submission/44356/3","title":"Veterinary Oncology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7634ae00-c073-4d8a-900a-ef5e13db820e","owner":[],"postedDate":"May 11th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"242131891160525008799353821848525870968","date":"2026-05-11T14:15:26+00:00","index":29,"fulltext":""},{"type":"reviewerAgreed","content":"129907692707782816105388275990681420516","date":"2026-04-29T17:18:01+00:00","index":15,"fulltext":""},{"type":"reviewersInvited","content":"19","date":"2026-04-29T14:43:58+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-11T06:27:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-11 06:27:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9534828","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9534828","identity":"rs-9534828","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}