Canine pulmonary adenocarcinoma (CPAC) is a rare, aggressive tumor with no established prognostic molecular biomarkers. The expression of monocarboxylate transporter 4 (MCT4) and glucose transporter 1 (GLUT1), key glycolysis-related proteins, is induced by hypoxia and is generally associated with poor prognosis in human pulmonary adenocarcinoma; however, their clinical significance in dogs remains unclear. This study investigated the expression of MCT4 and GLUT1 in 61 CPAC cases. Immunohistochemistry revealed significantly higher MCT4 and GLUT1 expression in tumors compared with normal lung tissues. High expression of both proteins was associated with lymph node metastasis. Kaplan-Meier analysis showed that high MCT4 expression was associated with prolonged overall survival, while GLUT1 showed no prognostic impact. However, MCT4 was not retained as an independent prognostic factor in multivariable Cox proportional hazards analysis. These results suggest that MCT4 and GLUT1 are upregulated in CPAC and may have distinct biological and clinical significance compared with human pulmonary adenocarcinoma.

This study aimed to determine the incidence of emesis in dogs receiving a low dose of intravenous medetomidine. Anesthetic records of dogs that received ≤3 µg/kg medetomidine intravenously before anesthesia induction were retrospectively reviewed. Data included demographics, doses, and the presence of emesis, retching, sialorrhea, or lip licking. A total of 155 cases met the criteria. The administered dose of medetomidine was 3.0 (0.5-3.0) µg/kg (median [range]). Emesis occurred in 3 of 155 dogs (1.9%), while retching, sialorrhea, and lip licking occurred in two, two, and five dogs, respectively. The incidence of emesis observed in dogs receiving low-dose (≤3 µg/kg) intravenous medetomidine was lower than that reported in studies using higher doses.

Most dogs with nonerosive immune-mediated polyarthritis (IMPA) have neutrophilic inflammation in the synovial fluid. On the other hand, some dogs with erosive IMPA have increased mononuclear cells as the most abundant cell subset in the synovial fluid. A 9-year-old, neutered female miniature dachshund presented with lameness and lethargy. Physical examination revealed subluxation of the carpal and tarsal joints. Synovial fluid tests revealed an increased number of leukocytes, mainly mononuclear cells, and radiographic examination led to a diagnosis of erosive IMPA. Compared with nonerosive IMPA, flow cytometric analysis of the synovial fluid in this case showed a significant expansion of T cells—predominantly CD8+ cytotoxic T cells—while monocyte and B cell counts remained comparable. Treatment with mycophenolate mofetil reduced leukocytes in the synovial fluid and improved the dog's activity, although bone erosion slowly progressed. Based on these findings, we propose that T cells, especially cytotoxic T cells, in synovial fluid contribute to inflammation in canine erosive IMPA and may be a therapeutic target.

Background:Encapsulating peritoneal sclerosis (EPS) is a rare clinical syndrome, either idiopathic or secondary to abdominal inflammation, characterized by fibrotic thickening of the peritoneum that encases the abdominal organs. Herein, we describe a case involving a relatively young cat initially suspected of having EPS based on clinical imaging findings, but ultimately diagnosed postmortem with peritoneal dissemination of exocrine pancreatic adenocarcinoma. Case Description:A 2-year-old castrated male domestic shorthair cat presented with abdominal distension and anorexia. The blood test results revealed no significant abnormalities. Imaging revealed severe ascites, digestive tract consolidation, pancreatic enlargement, and irregular peritoneal thickening with nodules. The ascitic fluid was negative for the feline coronavirus gene, and no increase in anti-feline coronavirus antibody titer was found in the blood. Given the patient's age, neoplastic disease was considered unlikely, and EPS was suspected based on the imaging findings. Despite receiving medical treatment with prednisolone, the cat died 19 days later. Postmortem examination revealed an exocrine pancreatic adenocarcinoma with abdominal and lung metastases. The peritoneal tissue formed a mass within the tumor, encapsulated the upper small intestine, caused ileus, and exhibited severe fibrosis. The cat was diagnosed with cancerous peritonitis, mimicking EPS based on histopathological findings. Conclusion:In the present case, peritoneal dissemination of exocrine pancreatic adenocarcinoma resulted in encapsulation of the gastrointestinal tract by thickened peritoneal tissue, producing clinical features that closely resembled EPS. Although antemortem diagnosis was challenging in this case, malignancy should be considered in the differential diagnosis when EPS is suspected. In addition, the possibility of neoplasia should be carefully considered, even in relatively young cats.

Canine haemangiosarcoma (HSA) is a highly aggressive cancer often associated with coagulation abnormalities. Statins, inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) clinically prescribed for hypercholesterolemia, are also believed to possess antitumour and anticoagulant properties by inhibiting downstream Akt activation. Akt phosphorylation is involved in the mechanism of the antitumour and tissue factor (TF)-lowering effects of statins. In the present study, we aimed to investigate whether statins could inhibit cell viability while concurrently inducing anticoagulant properties by regulating the expression of TFs in canine HSA cells. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), we initially exclusively detected HMGCR mRNA expression in canine HSA tissues and cell lines but not in normal cephalic vein and spleen tissues. Moreover, treatment with lipophilic statins, including atorvastatin, fluvastatin, and simvastatin, inhibited cell viability in a concentration-dependent manner and decreased TF expression both at the mRNA and protein levels, as evidenced by cell viability assays, RT-qPCR, and immunoblotting, respectively. Further investigation using cell viability assays and flow cytometry revealed that simvastatin decreased Akt phosphorylation, and MK-2206, a specific Akt inhibitor, mirrored the effect of simvastatin on cell viability and cell cycle arrest. However, MK-2206 exhibited different effects on TF expression depending on the cell type, indicating that Akt phosphorylation may not consistently regulate TF expression. Overall, this study provides insights into the potential therapeutic use of statins in targeting tumour growth and coagulation abnormalities in canine HSA. Further research is warranted to fully elucidate the underlying mechanisms and clinical applications of statins in canine HSA treatment.

Only a limited number of tumour biomarkers are currently available in veterinary medicine, particularly in cats. Cell-free DNA (cfDNA) is an extracellular DNA fragment released upon cell death and is considered a minimally invasive biomarker for the diagnosis and monitoring of various human malignancies. This study aimed to clarify the utility of circulating cfDNA as a liquid biopsy for various feline tumours. Plasma samples were collected from 44 cats with various tumours, 24 cats with other diseases and 10 healthy controls. A follow-up study was conducted in three tumour-bearing patients. All cfDNA concentrations were quantified via real-time polymerase chain reaction (PCR), which provided short and long fragments of a newly identified feline LINE-1 gene. We found that cfDNA levels were significantly higher in cats with various tumours than in those with other diseases or healthy controls. The cfDNA concentration was not correlated with serum amyloid A (SAA) levels. Cats with tumours exhibited elevated cfDNA levels that predicted tumour-bearing with a sensitivity and specificity of 50.5% and 91.2%, respectively (AUC 0.736; p < 0.001). In lymphoma cases, cats with high cfDNA levels had significantly shorter survival times than those with low cfDNA levels (median: 33 days vs. 178 days; p = 0.003). In addition, the cfDNA levels of the three patients correlated with clinical status during follow-up. Collectively, these findings indicate the potential of cfDNA as a useful biomarker for the diagnosis, therapeutic monitoring and prognostic assessment of tumours in cats.

Statins are inhibitors of the mevalonic acid pathway that mediates cellular metabolism by producing cholesterol and isoprenoids and are widely used in treating hypercholesterolaemia in humans. Lipophilic statins, including simvastatin, induce death in various tumour cells. However, the cytotoxic mechanisms of statins in tumour cells remain largely unexplored. This study aimed to elucidate the cytotoxic mechanisms of simvastatin in canine lymphoma cells. Simvastatin induced cell death via c-Jun N-terminal kinase (JNK) activation and autophagy in canine T-cell lymphoma cell lines Ema and UL-1, but not in B-cell lines. Cell death was mediated by induction of caspase-dependent apoptosis in UL-1 cells, but not in Ema cells. Blockade of autophagy by lysosomal inhibitors attenuated simvastatin-induced JNK activation and cell death. Isoprenoids, including farnesyl pyrophosphate and geranylgeranyl pyrophosphate, attenuated simvastatin-induced autophagy, JNK activation, and cell death. In UL-1 cells, simvastatin treatment resulted in the cell cycle arrest at the G2/M phase, which was altered to G0/1 phase cell cycle arrest by treatment with lysosomal inhibitors. These findings demonstrate that depletion of isoprenoids by simvastatin induces autophagy-mediated cell death via downstream JNK activation and cell cycle dysregulation in canine T-cell lymphoma cells.

Canine pulmonary adenocarcinoma (PAC) resembles human lung tumors in never-smokers, but it is rarer than human pulmonary adenocarcinoma. Therefore, research on canine PAC is challenging. In the present study, we successfully established various novel canine PAC cell lines from a single lesion in a dog, including two parent cell lines and fourteen cloned cell lines, and characterized their cellular properties in vitro. Several of these cell lines showed epithelial–mesenchymal transition (EMT)-like and/or cancer stem cell (CSCs)-like phenotypes. We additionally assessed the sensitivity of the cells to vinorelbine in vitro. Three clonal lines, two of which showed EMT- and CSC-like phenotypes, were resistant to vinorelbine. Furthermore, we evaluated the expression and activation status of EGFR, HER2, and Ras signaling factors. The findings indicated that the cell lines we established preserved the expression and activation of these factors to varying extents. These novel canine PAC cell lines can be utilized in future research for understanding the pathogenesis and development of treatments for canine PAC.

Canine pulmonary adenocarcinoma (PAC) resembles human lung tumors in never-smokers, but it is rarer than human pulmonary adenocarcinoma. Therefore, research on canine PAC is challenging. In the present study, we successfully established various novel canine PAC cell lines from a single lesion in a dog, including two parent cell lines and fourteen cloned cell lines, and characterized their cellular properties in vitro . Several of these cell lines showed epithelial–mesenchymal transition (EMT)-like and/or cancer stem cell (CSCs)-like phenotypes. We additionally assessed the sensitivity of the cells to vinorelbine in vitro . Three clonal lines, two of which showed EMT- and CSC-like phenotypes, were resistant to vinorelbine. These novel canine PAC cell lines can be utilized in future research for understanding the pathogenesis and development of treatments for canine PAC.

Cancers utilize a variety of molecules to escape host immune responses. Better understanding the immune environment surrounding cancer may facilitate application of innovative cancer immunotherapies, such as immune checkpoint inhibitors, to dogs as well as humans. In this study, we screened the expression of 20 immune regulatory molecules in diverse canine tumors (n = 59). Quantitative RT-PCR (qPCR) analysis revealed that some immune regulatory molecules, such as LGALS9 (coding Galectin-9) and CD48, were expressed in most canine tumors, but other molecules, such as CD274 (coding PD-L1), IL4I1, PVR, TNFSF18, ICOSLG, and TNFSF4, were rarely expressed. NECTIN2 was highly expressed in epithelial tumors but was low in non-epithelial tumors. In contrast, VSIR and CD200 expressions were low in epithelial tumors but high in non-epithelial tumors. Interestingly, several tumors expressed distinctive immunoregulatory factors. Hepatocellular carcinomas expressed FGL1, mast cell tumors expressed PDCD1LG2 (coding PD-L2), transitional cell carcinomas expressed VTCN1 (coding B7x), and lymphomas and squamous cell carcinomas expressed CD70. Consistent with qPCR results, immunofluorescence staining confirmed that hepatocellular carcinomas expressed FGL-1 protein. Thus, this study reveals the expression profile of immunoregulatory molecules in canine tumors and opens the door to better understanding the relationship between canine tumors and host immunity.

Statins are inhibitors of the mevalonate cascade that is responsible for cholesterol biosynthesis and the formation of intermediate metabolites, farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) used in the prenylation of proteins. Although statins are widely used in the treatment of hypercholesterolemia, recent studies suggest that they also inhibit proliferation of tumour cells by reducing prenylation of small GTP-binding proteins, such as, Ras. This study aimed to evaluate the effect of simvastatin on cell proliferation and Ras activation in various canine tumour cell lines, including hemangiosarcoma (HSA), melanoma, and lymphoma cell lines. Simvastatin inhibited cell proliferation of all cell lines tested in a concentration- and time-dependent manner, but the susceptibilities were different amongst the cell lines. Simvastatin induced apoptotic cell death via activation of caspase-3 and cell cycle arrest. The cytotoxic effects of simvastatin were attenuated by GGPP and FPP. Simvastatin decreased the amount of prenylated Ras and GTP-bound Ras in HSA and melanoma cell lines, but not in lymphoma cell lines. These results indicate that simvastatin induces cytotoxic effects through the depletion of GGPP and FPP in a variety of canine tumour cells, whereas multiple mechanisms are involved in the effects. Further study is required to elucidate the underlying mechanisms of simvastatin-induced cytotoxic effects in a variety of canine tumour cells.

A 9-year-old male intact domestic cat weighing 4.6 kg was referred for tachypnea. A large mass was visible in computed tomography (CT) scans of the thoracic cavity. A histopathological evaluation of the mass was consistent with thymoma. The cat was treated with 2 × 8 Gy intensity modulated radiation therapy and sulfoquinovosyl acyl propanediol (SQAP). Post radiation therapy (RT), the tumor structure appeared cystic in the CT, and the tumor volume decreased by approximately 80% after aspiration than that before aspiration. The tumor was removed surgically. RT treatment with SQAP made it possible to treat the thymoma with a low total radiation dose.

Microparticle (MP)-associated tissue factor (TF) activity in plasma might play a role in human disseminated intravascular coagulation (DIC). The aim of this study was to compare MP-TF activity between non-DIC and DIC groups. Ten clinically healthy beagles and 26 diseased dogs were enrolled. The proportion of dogs with increased MP-TF activity was significantly higher in the DIC group than the non-DIC group (P=0.014). MP-TF activity in the DIC group was significantly higher than the non-DIC group (P=0.021). MP-TF activity positively correlated with plasma D-dimer concentration (r=0.42, P=0.034). Moreover, MP-TF activity was decreased by the time of recovery in some dogs with DIC. Larger prospective studies are warranted to assess its value as a diagnostic and prognostic biomarker in DIC.

Hypercoagulability is a common paraneoplastic complication in dogs with various malignant tumors. Importantly, tissue factor procoagulant activity (TF-PCA) induced by TF-bearing microparticles (TF-MPs) is associated with hypercoagulability in human patients with cancer. However, TF-PCA in tumor cells and the association between circulating TF-MPs and hypercoagulability in dogs with malignant tumors remain poorly understood. Therefore, the present study was conducted to evaluate the TF-PCA in various types of canine tumor cell lines and plasma in dogs with malignant tumors. Mammary gland tumor, hemangiosarcoma, and malignant melanoma cell lines, but not lymphoma cell lines, expressed TF on their surfaces and showed cellular surface and MP-associated TF-PCA. The plasma TF-PCA was elevated in some dogs that naturally developed such tumors. No significant difference was observed in plasma TF-PCA between the disseminated intravascular coagulation (DIC) group (median: 43.40; range: 3.47–85.19; n=5) and non-DIC group (median: 7.73; range: 1.70–16.13; n=12). However, plasma TF-PCA was remarkably elevated in three of five dogs with DIC. To the best of our knowledge, this is the first study to evaluate plasma TF-PCA in dogs with malignant tumors. Further studies must be conducted to determine the cellular origin of TF-MPs and the efficacy of plasma TF-PCA as a biomarker of DIC in dogs with malignant tumors.

A 16-year-old spayed female American Shorthair cat was presented with lethargy, anorexia, and wamble. Physical and blood examination did not reveal any remarkable findings. Abdominal ultrasonography identified the presence of a localized anechoic structure with a thick wall in contact with the small intestine and adjacent to the liver. Ultrasound-guided fine-needle aspiration of the structure revealed fluid containing numerous cocci and neutrophils. Two days after antibiotic treatment, exploratory laparotomy was performed and the content of the structure was removed before multiple lavages. The pathological and bacteriological examination results supported a confirmatory diagnosis of pancreatic abscess due to Staphylococcus aureus infection, making this the first such report in a cat. The cat remained healthy thereafter with no disease recurrence.

A 2-year-old female beagle was referred to our hospital for evaluation of anemia. Laboratory tests, including bone marrow cytology, revealed non-regenerative immune-mediated anemia (NRIMA). Although initial immunosuppressive multi-drug therapy was not effective, additional administration of danazol was successful in treating the anemia. However, hepatocellular carcinoma (HCC) developed about 20 months after the administration of danazol. In humans, several cases of development of HCC after the administration of danazol have been reported. The present report describes a case of HCC development in a dog after chronic administration of danazol in addition to other immunosuppressive drugs.

Hypoxic conditions in various cancers are believed to relate with their malignancy, and hypoxia inducible factor-1α (HIF-1α) has been shown to be a major regulator of the response to low oxygen. In this study, we examined HIF-1α expression in canine lymphoma using cell lines and clinical samples and found that these cells expressed HIF-1α. Moreover, the HIF-1α inhibitors, echinomycin, YC-1 and 2-methoxyestradiol, suppressed the proliferation of canine lymphoma cell lines. In a xenograft model using NOD/scid mice, echinomycin treatment resulted in a dose-dependent regression of the tumor. Our results suggest that HIF-1α contributes to the proliferation and/or survival of canine lymphoma cells. Therefore, HIF-1α inhibitors may be potential agents to treat canine lymphoma.

24 Hypoxic conditions in various cancers are believed to relate with their malignancy, and hypoxia inducible 25 factor-1α (HIF-1α) has been shown to be a major regulator of the response to low oxygen. In this study, we examined 26 HIF-1α expression in canine lymphoma using cell lines and clinical samples and found that these cells expressed HIF27 1α. Moreover, the HIF-1α inhibitors, echinomycin, YC-1 and 2-methoxyestradiol, suppressed the proliferation of canine 28 lymphoma cell lines. In a xenograft model using NOD/scid mice, echinomycin treatment resulted in a dose-dependent 29 regression of the tumor. Our results suggest that HIF-1α contributes to the proliferation and/or survival of canine 30 lymphoma cells. Therefore, HIF-1α inhibitors may be potential agents to treat canine lymphoma. 31 32