Liver lobe torsion is an uncommon but potentially lethal emergency in dogs. When a lobe twists, venous outflow is obstructed first, leading to congestion, thrombosis, and eventually ischemic necrosis of the tissue. If definitive treatment is delayed, the cascade can progress to peritoneal effusion, shock, sepsis, and death. Most of what veterinarians know about the condition comes from individual case reports and small retrospective series, because large-scale data simply do not exist. The clinical signs are frustratingly nonspecific: lethargy, anorexia, vomiting, abdominal pain, increased thirst and urination, fluid in the abdomen, and acute collapse can all point to many different diseases. Classically, medium- to large-breed, middle-aged to older dogs are overrepresented, and the left lateral lobe is the most commonly affected, presumably because of its size, mobility, and relative anatomical separation from adjacent lobes. But cases in small breeds and even puppies have been reported, meaning signalment alone should never rule the condition out.

When the Corgi arrived at the hospital, she was dull and showed mild abdominal pain. Her rectal temperature was 38.0 degrees Celsius, her heart rate was elevated at 140 beats per minute, and her non-invasive systolic blood pressure measured 90 mmHg. Bloodwork told a striking story: alanine aminotransferase, an enzyme released by damaged liver cells, was markedly elevated at 1228 U/L against a reference interval of 10 to 125. Aspartate aminotransferase reached 248 U/L, C-reactive protein, a marker of systemic inflammation, was six times the upper limit of normal at 6.0 mg/dL, and platelets were elevated at 678 × 10³/µL, a finding consistent with an inflammatory response. Mild increases in total protein and globulin rounded out a picture of significant hepatic injury and inflammation.

Abdominal radiographs revealed a large, well-defined mass in the cranial abdomen that was displacing adjacent organs caudally. Ultrasonography identified an approximately 7 cm mass between the left aspect of the liver and the spleen, along with a small volume of anechoic peritoneal effusion. Critically, color Doppler imaging detected no blood-flow signal within the mass, a red flag for vascular compromise. However, ultrasound alone could not definitively establish the diagnosis. That task fell to computed tomography, which proved to be the decisive diagnostic tool. The CT scan identified a 7.2 × 6.7 × 6.5 cm hepatic mass with a whirl sign at its base, the characteristic swirling appearance created by a twisted vascular pedicle. On the multiplanar portal venous-phase dataset, the twisted pedicle could be traced continuously to the portal venous branch supplying the left medial liver lobe. The mass also contained a non-enhancing hypoattenuating region measuring 15 to 22 Hounsfield units, consistent with necrosis secondary to vascular obstruction.

The whirl sign deserves particular attention because it is considered highly supportive of torsion when present, yet it can be missed or unobtainable with standard radiography and ultrasonography. In a comparative report of ultrasonographic and CT findings in dogs with liver lobe torsion, ultrasonography was suggestive of the condition in only one of five cases, whereas CT was fundamental for presurgical diagnosis in all of them. The present case reinforces that pattern: conventional imaging identified a mass and effusion but did not establish the torsion, while CT demonstrated the affected lobe, the necrotic non-enhancing parenchyma, and the whirl sign all at once. For atypical presentations, especially those complicated by a large hepatic mass or a peripheral torsion site, the authors argue that CT should be the modality of choice when liver lobe torsion is suspected.

Surgery proceeded after medical stabilization. The dog was premedicated with midazolam and fentanyl, anesthetized with propofol, and maintained on isoflurane with a fentanyl constant rate infusion, with perioperative dopamine, lactated Ringer’s solution, and the protease inhibitor nafamostat mesilate administered as needed. A midline celiotomy exposed a torsed left medial liver lobe that was dark and congested with partially pale-yellow areas, the gross signature of venous obstruction and ischemic necrosis. The rotation was identified as clockwise at the base of the mass. Importantly, the surgical team resected the lobe without detorsion, a deliberate choice designed to reduce the risk of thromboembolism and the systemic release of toxic metabolites from the ischemic tissue. The pedicle was double ligated proximal to the torsed site with monofilament polyglyconate suture and transected, and the remaining hepatic parenchyma near the hilus showed no gross evidence of neoplasia.

Histopathology delivered the second surprise. The resected tissue, fixed in formalin, embedded in paraffin, sectioned at 4 micrometers, and stained with hematoxylin and eosin, confirmed hepatocellular carcinoma with extensive necrosis. Neoplastic hepatocytes were arranged in irregular cord-like to solid patterns, and normal portal triad structures were absent within the lesion. The surgical margin was free of neoplastic cells, and the adherent falciform ligament contained only localized granulation tissue without malignancy. Fluid collected from the abdomen during surgery was classified as a culture-negative inflammatory exudate, likely related to hepatic necrosis or tumor-associated inflammation. The combination of a torsed lobe and a malignant tumor at the twist point raised an intriguing mechanical hypothesis: a large exophytic or pedunculated mass may alter weight distribution and increase rotational mobility of the lobe, creating conditions favorable to torsion.

Comparable phenomena have been documented in human medicine, though not identically. Pedunculated hepatocellular carcinomas and hepatic hemangiomas have been reported to twist around their vascular stalks in people, presenting as acute abdominal emergencies requiring surgical resection. These reports lend plausibility to the idea that a bulky, mobile tumor can act as a mechanical fulcrum. However, the authors are careful to note that such reports do not establish a common mechanism, and a causal relationship between hepatocellular carcinoma and liver lobe torsion cannot be determined from a single case. Prior veterinary literature offers only scattered precedents: a cat with right medial torsion and concurrent hemoabdomen from a ruptured hepatocellular carcinoma, one dog among a retrospective series of massive hepatocellular carcinomas with torsion of a neoplastic left lateral lobe, and a case associated with hepatic hemangiosarcoma. What distinguishes the Corgi is the location of the rotational axis at the base of the tumor, distal to the lobar hilus, with the proximal hepatic parenchyma entirely free of tumor.

The outcome was remarkably good. The dog recovered from anesthesia without incident, resumed voluntary food intake the day after surgery, and was discharged on postoperative Day 4 with an active suction drain removed on Day 3 after output fell below 1 mL/kg/day. No major complications, including hemorrhage, thrombosis, pancreatitis, or sepsis, occurred. At the two-week recheck, the preoperative lethargy, inappetence, and abdominal pain had resolved, and liver enzymes and inflammatory markers were falling, though still above reference intervals. By one year, the dog had gained 10 percent body weight, her activity level had markedly improved, and ALT, AST, ALP, and C-reactive protein had all normalized, with only platelets slightly elevated. Thoracic radiography and abdominal ultrasonography showed no evidence of recurrence or metastasis, and she maintained an excellent quality of life.

The report carries honest limitations. It describes a single dog, so the role of hepatocellular carcinoma as a predisposing factor for torsion remains speculative. Hepatic tissue proximal to the torsion was not examined histologically, immunohistochemistry was not performed, and follow-up imaging did not include CT, meaning subclinical recurrence or distant metastasis cannot be entirely excluded. Larger case series would be needed to determine whether primary hepatic neoplasia is a true risk factor. Nevertheless, the clinical lessons are clear and actionable. Liver lobe torsion can occur in small, geriatric patients, and concurrent cancer and advanced age should not automatically preclude surgery when complete resection appears feasible and perioperative stabilization can be achieved. For veterinarians facing a cranial abdominal mass with absent Doppler flow, the whirl sign on CT may be the key that unlocks a definitive preoperative diagnosis and a curative surgical plan, as it was for this resilient Corgi.

Subject of Research: Liver lobe torsion associated with hepatocellular carcinoma in a dog

Article Title: Left Medial Liver Lobe Torsion Associated With Hepatocellular Carcinoma in a Pembroke Welsh Corgi: A Case Report

Article References: Shinoda, H., Mori, K., Mori, H., Ishigaki, K., & Asano, K. (2026). Left Medial Liver Lobe Torsion Associated With Hepatocellular Carcinoma in a Pembroke Welsh Corgi: A Case Report. Veterinary Medicine and Science, 12(6), Article e71261. https://doi.org/10.1002/vms3.71261

Image Credits: AI Generated

DOI: 10.1002/vms3.71261

Keywords: liver lobe torsion, hepatocellular carcinoma, veterinary medicine, computed tomography, whirl sign, Pembroke Welsh Corgi, liver lobectomy, canine oncology, ischemic necrosis, case report, surgical treatment, small animal surgery

Primary tumours of the liver and biliary system are genuinely rare in cats, accounting for only about 1.0 to 2.9 percent of all feline neoplasms. They can arise from hepatocytes, the biliary epithelium, neuroendocrine cells or connective tissue elements, producing a histologically diverse group of diseases with very different behaviours. Because these tumours are uncommon, most published evidence has consisted of small single-institution case series, which has made it difficult for clinicians to give owners accurate prognostic information. The new study, led by Carolyn Averil Hylton and Matteo Rossanese of the Royal Veterinary College with colleagues at Colorado State University, the University of Bologna and the San Marco Veterinary Clinic, set out to close that evidence gap by pooling cases treated between 2003 and 2024.

The cohort was dominated by domestic shorthairs, reflecting the general cat population, with a median age of 12 years and a median body weight of 4.8 kilograms. Only eight of the 76 cats were asymptomatic; in these animals a mass was discovered incidentally during investigations for unrelated problems. The rest presented with the vague, non-specific signs typical of feline hepatic disease: lethargy, reduced appetite, progressive weight loss, vomiting and abdominal distension. Advanced cases could show icterus, clotting abnormalities and excessive thirst and urination, all signs of failing liver function. The median duration of clinical signs before presentation was 29 days, a reminder of how quietly these tumours can grow in a species that hides illness well.

Diagnostic workups revealed the scale of the problem. Imaging identified hepatic masses with a median maximal diameter of 5.5 centimetres, with the largest reaching 13 centimetres, an extraordinary volume for a feline liver. The left division of the liver was involved in 40 of the 76 cases, the central division in 22 and the right division in 14. The overwhelming majority of tumours, 85.5 percent, were of the massive solitary type rather than nodular or diffuse. Biliary cystadenoma, a benign tumour of the bile duct epithelium, was the most common diagnosis with 30 cases, followed by hepatocellular carcinoma with 19, hepatocellular adenoma with 11 and biliary carcinoma with 11, alongside small numbers of haemangiosarcomas and neuroendocrine carcinomas.

Preoperative diagnosis proved as difficult as the literature suggests. Nearly two-thirds of the masses were sampled before surgery, mostly by fine needle aspiration, but cytology matched the final histopathology in only 22 of those samples, was inconclusive in 11 and flatly wrong in 9, and in two further cases the pathologists could not distinguish adenoma from carcinoma. All seven tru-cut biopsy samples, by contrast, proved accurate. The study also uncovered biochemical patterns that may help clinicians refine their suspicion. Cats with biliary carcinoma had markedly elevated total bilirubin concentrations, with a median of 191 micromoles per litre, likely reflecting mechanical obstruction of bile flow, whereas cats with biliary cystadenoma had a median bilirubin of just 3 micromoles per litre. Cats with the benign cystadenomas also had significantly lower ALT and ALP liver enzyme values than cats with malignant tumours, consistent with the greater hepatocyte injury caused by carcinomas.

All 76 cats underwent exploratory abdominal surgery performed by or under the direct supervision of board-certified veterinary surgeons, with complete liver lobectomy in 66 cases and partial lobectomy in 10. A third of the cats required resection of more than one liver lobe, an operationally significant finding that underscores how large and invasive these masses can be. The authors suggest the predominance of left-sided tumours may partly reflect surgical selection bias: left lateral masses sit away from the gallbladder, bile ducts and hepatic hilus and are easier to resect, so surgeons and owners may historically have opted for surgery mainly in that anatomically favourable setting. Still, a genuine biological predilection for the larger left hepatic parenchyma cannot be excluded.

The headline safety data are striking. Intraoperative complications occurred in 11 cats, about 15 percent, including four severe haemorrhagic events. Postoperatively, 17 cats, 22 percent, experienced complications ranging from hyperthermia and anaemia requiring transfusion to anorexia severe enough to need a feeding tube. Seven cats died as a result of perioperative complications, giving an overall mortality rate of just 9 percent, with 69 of 76 cats surviving to hospital discharge. The median hospitalisation was four days. Earlier reports had put survival to discharge as low as 40 percent, so the authors argue that improvements in diagnostics, anaesthesia and surgical technique over recent decades have fundamentally changed the risk calculus for this operation.

Survival analysis, using Kaplan–Meier curves and Cox proportional hazards modelling, showed that histological diagnosis was the only factor significantly associated with survival. Median tumour-specific survival for cats with malignant tumours was 673 days, compared with 2916 days for benign tumours, a difference that was highly statistically significant. Among the malignant subtypes, cats with hepatocellular carcinoma lived a median of 859 days and those with biliary carcinoma 387 days, while for biliary cystadenoma the median survival was never reached during follow-up, which extended to nearly eight years in some patients. Notably, incomplete surgical margins did not significantly affect survival, nor did tumour size or location, although the authors caution that the mix of benign and malignant lesions among incompletely excised tumours may have muddied that comparison.

Recurrence and metastasis rates appeared reassuringly low, at 18 and 25 percent respectively among the cats for which restaging data were available, occurring between 30 and 840 days and 30 and 435 days after surgery. However, the authors flag an important limitation: only 28 of the 69 surviving cats underwent any follow-up restaging, so the true recurrence figures remain uncertain. Only four cats received postoperative chemotherapy, too few to draw any conclusion about the value of adjunctive therapy. The retrospective design also introduces selection bias, since cats deemed inoperable, those with metastatic disease at diagnosis and those euthanised without surgery were necessarily excluded, likely inflating the reported survival times.

Even with those caveats, the study delivers a clear and clinically actionable message. Liver lobectomy for feline hepatobiliary tumours carries a low mortality rate, and even cats with hepatocellular or biliary carcinoma can achieve favourable survival measured in years rather than weeks, outcomes consistent with recent smaller studies and broadly comparable to results in dogs. The authors recommend that clinicians actively discuss surgical options with owners of cats presenting with hepatic masses rather than defaulting to palliative management on the basis of outdated expectations. They also propose that surgery should be considered for masses outside the anatomically convenient left division, and that marked bilirubin elevations may warrant heightened suspicion of biliary carcinoma when cytology is inconclusive. Larger prospective studies will be needed to identify reliable prognostic factors and define the role of chemotherapy, but for now, the message to feline practitioners is one of cautious optimism: for many cats with primary liver tumours, surgery works, and it works better than the old textbooks ever admitted.

Subject of Research: Survival and prognostic factors in cats undergoing surgery for primary non-lymphomatous hepatobiliary tumours

Article Title: Evaluation of survival and prognostic factors in cats undergoing surgery for primary non-lymphomatous hepatobiliary tumours

Article References: Hylton, C. A., Guillén, A., Altwal, J., Tremolada, G., Cinti, F., Magno, S. D., & Rossanese, M. (2026). Evaluation of survival and prognostic factors in cats undergoing surgery for primary non-lymphomatous hepatobiliary tumours. Veterinary Oncology, 3(1), Article 2. https://doi.org/10.1186/s44356-025-00053-0

Image Credits: AI Generated

DOI: 10.1186/s44356-025-00053-0

Keywords: feline, hepatobiliary tumours, liver lobectomy, veterinary oncology, hepatocellular carcinoma, biliary cystadenoma, biliary carcinoma, prognostic factors, tumour-specific survival, surgical complications, retrospective study, liver enzymes