In human and dogs, bladder cancer (BC) is the most common neoplasm affecting the urinary tract. Dog BC resembles human muscle‐invasive BC in histopathological characteristics and gene expression profiles, and could be an important research model for this disease. Cancer patient‐derived organoid culture can recapitulate organ structures and maintains the gene expression profiles of original tumor tissues. In a previous study, we generated dog prostate cancer organoids using urine samples, however dog BC organoids had never been produced. Therefore we aimed to generate dog BC organoids using urine samples and check their histopathological characteristics, drug sensitivity, and gene expression profiles. Organoids from individual BC dogs were successfully generated, expressed urothelial cell markers (CK7, CK20, and UPK3A) and exhibited tumorigenesis in vivo. In a cell viability assay, the response to combined treatment with a range of anticancer drugs (cisplatin, vinblastine, gemcitabine or piroxicam) was markedly different in each BC organoid. In RNA‐sequencing analysis, expression levels of basal cell markers (CK5 and DSG3) and several novel genes (MMP28, CTSE, CNN3, TFPI2, COL17A1, and AGPAT4) were upregulated in BC organoids compared with normal bladder tissues or two‐dimensional (2D) BC cell lines. These established dog BC organoids might be a useful tool, not only to determine suitable chemotherapy for BC diseased dogs but also to identify novel biomarkers in human muscle‐invasive BC. In the present study, for the 1st time, dog BC organoids were generated and several specifically upregulated organoid genes were identified. Our data suggest that dog BC organoids might become a new tool to provide fresh insights into both dog BC therapy and diagnostic biomarkers.

A 6-year-old neutered male Yorkshire Terrier presented with recurrent pericardial effusion. Although clinical examinations including computed tomography were inconclusive, an exploratory thoracotomy revealed multiple small nodules and plaques on the inner surface of the pericardial sac (Day 1). A subtotal pericardiectomy was performed to prevent cardiac tamponade due to the increasing pericardial effusion, and the resected section of the pericardium was histopathologically diagnosed with mesothelioma. After surgery, chemotherapy with intrathoracic carboplatin was commenced. During the course of the treatment, a detailed follow-up ultrasonographic scan was performed to detect early lesions disseminated on the pleura, originating from the primary pericardial mesothelioma. On Day 101, the minute pleural nodules, which were disseminated lesions as predicted, were successfully imaged by ultrasonography. As the clinical stage advanced, the nodules were observed to gradually increase in size and number, implying tumor progression. These observations highlight the feasibility of ultrasonography in detecting minute disseminated lesions at an early stage, monitoring tumor progression, and thereby, predicting the prognosis of canine pericardial mesothelioma.

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A 15-year-old neutered male Persian cat was presented with recurrent hematemesis and melena. Abdominal ultrasonography and computed tomography revealed a mass in the proximal descending duodenal wall. Endoscopic examination revealed hemorrhage on the luminal side of the mass. Fine-needle aspiration of the mass was performed. Microscopic analysis revealed a cluster of cells with oval nuclei and indistinct cell borders, suggesting a neoplastic disease of neuroendocrine origin. The mass located near the major duodenal papilla was partially resected, and the bleeding was stopped by cauterization. However, the surgical procedures could not control the hemorrhage from the tumor mass, and the cat died of severe anemia. Immunohistopathological analysis revealed that the tumor was a duodenal carcinoid.

A neutered male Golden Retriever was referred with a 2-week history of dry mouth. Multiple and bilateral enlargement of the lacrimal and salivary glands showing heterogeneous internal enhancement was identified on contrast-enhanced computed tomography (CT). Ultrasonographic examination detected multifocal hypoechoic areas within the swollen submandibular salivary glands, which were histopathologically diagnosed as lymphoplasmacytic sialoadenitis. As both imaging and histopathological findings were in accordance with those in human Sjögren’s syndrome, a provisional diagnosis of Sjögren’s-like syndrome was made. Immunosuppressive drugs promptly improved clinical signs concurrently with the abnormal sonographic findings, indicating the feasibility of ultrasonography in monitoring therapeutic outcomes. Herein, we discuss a proposed criteria set for diagnosis of Sjögren’s-like syndrome in veterinary medicine.