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Intestinal lymphangiectasia (IL) is a common complication in dogs. Since nitric oxide (NO) is known to relax the lymphatic vessel, we evaluated inducible NO synthase (iNOS) expression using immunohistochemistry in 13 dogs with lymphoplasmacytic enteritis (LPE) with or without IL. The duodenal iNOS expressing cells were significantly increased in dogs with IL-negative or IL-positive LPE dogs (P=0.025, P=0.007) compared with control dogs. However, there was no significant difference in iNOS expression between IL-positive and IL-negative tissues. Based on these results, there is no clear evidence for the NO overproduction in the pathogenesis of IL in dogs with LPE. Factors other than NO could, thus, contribute to IL in dogs with LPE.

Merkel cell carcinoma (MCC) is a cutaneous neuroendocrine tumor. We recently demonstrated that cats with MCC often have other proliferative cutaneous lesions, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Based on this finding, we hypothesize that Felis catus papillomavirus (FcaPV) is involved in the development of MCC in cats, similar to SCC and BCC. To investigate this hypothesis, the presence of FcaPV nucleic acid and immunoreactivity for tumor suppressor proteins were examined in 21 feline MCC cases. Polymerase chain reaction using FcaPV type-specific primers detected FcaPV2 DNA in 20/21 samples of MCC. The complete FcaPV2 sequence was characterized in one case. In situ hybridization for FcaPV2 E7 revealed punctate nuclear signals within tumor cells in 19/21 MCC. Increased immunoreactivity for p16CDKN2A protein and decreased immunoreactivity for retinoblastoma (pRb) and p53 proteins were observed in 20/21 MCC. These results suggest that feline MCC cases are infected with FcaPV2 and the subsequent inhibition of pRb and p53 induced by integrated viral oncogenes is associated with feline MCC tumorigenesis, similar to other PV-induced proliferative cutaneous lesions. On the other hand, the single case of FcaPV2-negative MCC showed strong p53 immunoreactivity, suggesting mutations in p53 caused by cancer inducers other than FcaPV2 infection in this case. The present study suggests FcaPV2 as a cause of feline MCC.

Canine cutaneous lymphoma is an uncommon lymphoma in dogs. Most canine cutaneous lymphoma cases have a T-cell origin. Canine cutaneous T-cell lymphoma (CTCL) is classified into epitheliotropic and nonepitheliotropic cutaneous lymphomas, and each type of lymphoma is subclassified into several histological subtypes. Limited information is available regarding the prognostic significance of clinical variables and histopathological subtypes in dogs with CTCL. This retrospective study aimed to investigate the influence of clinical variables and histopathological subtypes on the prognosis of dogs with CTCL. Forty-six dogs diagnosed with CTCL by histopathological examination were included. Histopathological specimens were reexamined and classified into CTCL subtypes. The influence of the type of skin lesion, histopathological subtype, haematological examination results and treatment response on the overall survival time (OS) was examined. Thirty-one dogs were diagnosed with epitheliotropic CTCL (mycosis fungoides in 28 dogs; pagetoid reticulosis in 3 dogs) and 15 dogs were diagnosed with nonepitheliotropic CTCL (anaplastic large T-cell lymphoma in 6 dogs; peripheral T-cell lymphoma, not otherwise specified, in 9 dogs). The OS of dogs diagnosed with epitheliotropic CTCL (141 days) was significantly shorter than that of dogs diagnosed with nonepitheliotropic CTCL (374 days). As clinical variables, the presence of neoplastic lymphocytes in peripheral blood, thrombocytopenia and initial chemotherapeutic response was related to prognosis. Our results demonstrated that histopathological subtype and several clinical variables were found to influence the prognosis of dogs with CTCL.

Background: Rabbits, ferrets, and four-toed hedgehogs are popular exotic pets, but comprehensive epidemiological studies in these animals have been rarely conducted. The present study aims to clarify the incidence of neoplastic and non-neoplastic diseases in pet rabbits, ferrets and four-toed hedgehogs in Japan. Methods: We histologically/cytologically investigated 1098 samples from 883 rabbits, 812 samples from 521 ferrets and 561 samples from 468 four-toed hedgehogs that were collected at Miwa Exotic Animal Hospital and submitted to the Laboratory of Veterinary Pathology, The University of Tokyo between 2006 and 2020. The examinations of necropsy samples were not included in the present study. Results: Of the 1098 samples from diseased rabbits, 721 (65.7%) were diagnosed as neoplastic and 377 (34.3%) were as non-neoplastic. Uterine adenocarcinoma (21.1%), cutaneous soft tissue sarcoma (15.1%) and mammary gland adenocarcinoma (8.2%) were the most commonly encountered neoplasms. Endometrial hyperplasia (35.8%), testicular atrophy (4.2%) and uterine adenomyosis (3.7%) were the most common non-neoplastic lesions in rabbits. Of the 812 samples from diseased ferrets, 487 (60.0%) were diagnosed as neoplastic and 325 (40.0%) were as non-neoplastic. Adrenocortical tumor (23.2%), lymphoma (19.3%) and pancreatic islet cell tumor (11.5%) were the most commonly encountered neoplasms. Extramedullary hematopoiesis in the spleen (10.5%), lymph node hyperplasia (7.7%) and cholangiohepatitis (4.6%) were the most common non-neoplastic lesions in ferrets. Of the 561 samples from diseased hedgehogs, 338 (60.2%) were diagnosed as neoplastic and 223 (39.8%) were as non-neoplastic. Endometrial stromal tumor and endometrial mixed tumor (23.7%), oral squamous cell carcinoma (13.0%) and cutaneous soft tissue sarcoma (11.5%) were the most commonly encountered neoplasms. Gingivitis/stomatitis (39.5%), endometrial hyperplasia (18.8%) and dermatitis (6.7%) were the most common non-neoplastic lesions in hedgehogs. Conclusions and clinical relevance: Information obtained from the present study will provide a useful reference for veterinarians working with these exotic animals. Based on the literature search, this is the largest-scale retrospective study on disease incidence in hedgehogs.

Canavan disease is an autosomal recessive leukodystrophy caused by mutations in the gene encoding aspartoacylase (ASPA), which hydrolyses N-acetylaspartate (NAA) to acetate and aspartate. A similar feline neurodegenerative disease associated with a mutation in the ASPA gene is reported herein. Comprehensive clinical, genetic, and pathological analyses were performed on 4 affected cats. Gait disturbance and head tremors initially appeared at 1 to 19 months of age. These cats eventually exhibited dysstasia and seizures and died at 7 to 53 months of age. Magnetic resonance imaging of the brain revealed diffuse symmetrical intensity change of the cerebral cortex, brainstem, and cerebellum. Gas chromatography–mass spectrometry analysis of urine showed significant excretion of NAA. Genetic analysis of the 4 affected cats identified a missense mutation (c.859G>C) in exon 6 of the ASPA gene, which was not detected in 4 neurologically intact cats examined as controls. Postmortem analysis revealed vacuolar changes predominantly distributed in the gray matter of the cerebrum and brain stem as well as in the cerebellar Purkinje cell layer. Immunohistochemically, these vacuoles were surrounded by neurofilaments and sometimes contained MBP- and Olig2-positive cells. Ultrastructurally, a large number of intracytoplasmic vacuoles containing mitochondria and electron-dense granules were detected in the cerebral cortex. All 4 cats were diagnosed as spongy encephalopathy with a mutation in the ASPA gene, a syndrome analogous to human Canavan disease. The histopathological findings suggest that feline ASPA deficiency induces intracytoplasmic edema in neurons and oligodendrocytes, resulting in spongy degeneration of the central nervous system.

There has been an increase in the number of Jack Russell Terriers (JRTs) diagnosed with adenomas and adenocarcinomas of the gastrointestinal tract in Japan. This study retrospectively investigated the clinical and histopathological features and prognosis of adenocarcinomas arising in the gastrointestinal tract in JRT dogs. Seven JRTs and 39 dogs of other breeds diagnosed with gastrointestinal adenocarcinoma were included in the study. The most common sites of gastrointestinal adenocarcinoma in JRTs were the pylorus and rectum. On histopathological examination, these adenocarcinomas showed a papillary or tubular growth pattern, and the lesions were confined within the mucosal epithelium and poorly invasive. Among all dogs with gastric adenocarcinoma, the median survival time (MST) for five of the JRTs could not be determined because more than half of the cases remained alive, while the MST for nine non-JRT dogs was 34 days. Among all dogs with adenocarcinoma in the large intestine, the MST for three of the JRTs could not be determined, while the MST for nine non-JRT dogs was 1,973 days. The difference in MST between JRT and non-JRT dogs with gastric adenocarcinoma was significant (P=0.0220). Since gastrointestinal adenocarcinomas in JRTs show distinct characteristics with respect to their clinical features, treatment course, and prognosis, a different surgical and medical treatment plan should be considered compared to the management of gastrointestinal adenocarcinomas in other dog breeds.

Anterior temporal lobectomy (ATL) is a surgical procedure for drug-resistant mesial temporal lobe epilepsy that is commonly performed in human medicine. The purpose of this study was to determine whether ATL-like surgery, i.e., removal of the amygdala and hippocampal head, is possible in dogs, and to investigate its safety and postoperative complications. Eight healthy beagles underwent ATL-like surgery and were observed for 3 months postoperatively. Samples from the surgically resected tissues and postmortem brain were evaluated pathologically. The surgical survival rate was 62.5%. The major postoperative complications were visual impairment, temporal muscle atrophy on the operative side, and a postoperative acute symptomatic seizure. Due to the anatomical differences between dogs and humans, the surgically resected area to approach the medial temporal structures in dogs was the ventrolateral part of the temporal lobe. Therefore, the ATL-like surgery described in this study was named "ventrolateral temporal lobectomy" (VTL). This study is the first report of temporal lobectomy including amygdalohippocampectomy in veterinary medicine and demonstrates its feasibility. Although it requires some degree of skill, VTL could be a treatment option for canine drug-resistant epilepsy and lesions in the mesial temporal lobe.

Rhabdomyosarcoma (RMS) is an aggressive type of soft tissue sarcoma, and pleomorphic RMS is a rare subtype of RMS found in adult. p16 is a tumor suppressor which inhibits cell cycle. In human RMS, p16 gene is frequently deleted, but p16-null mice do not develop RMS. We reported that genetic ablation of p16 by the crossbreeding of p16 knock-out rats (p16-KO rats) improved the dystrophic phenotype of a rat model of Duchenne muscular dystrophy (Dmd-KO rats). However, p16/Dmd double knock-out rats (dKO rats) unexpectedly developed sarcoma. In the present study, we raised p16-KO, Dmd-KO, and dKO rats until 11 months of age. Twelve out of 22 dKO rats developed pleomorphic RMS after 9 months of age, while none of p16-KO rats and Dmd-KO rats developed tumor. The neoplasms were connected to skeletal muscle tissue with indistinct borders and characterized by diffuse proliferation of pleomorphic cells which had eosinophilic cytoplasm and atypical nuclei with anisokaryosis. For almost all cases, the tumor cells immunohistochemically expressed myogenic markers including desmin, MyoD, and myogenin. The single cell cloning from tumor primary cells gained 20 individual Pax7-negative MyoD-positive RMS cell clones. Our results demonstrated that double knock-out of p16 and dystrophin in rats leads to the development of pleomorphic RMS, providing an animal model that may be useful to study the developmental mechanism of pleomorphic RMS.

Copy number gain (CNG) and/or protein overexpression of ErbB2 have been observed in human breast cancer patients and are associated with poor prognosis. Similarly, ErbB2 overexpression has also been observed in canine mammary carcinoma; however, data on ErbB2 copy number is limited. The purposes of this study were to evaluate ErbB2 copy number in dogs with mammary carcinoma and to investigate associations of ErbB2 CNG with ErbB2 expression, histological and clinical characteristics, and survival. DNA samples were isolated from 59 formalin-fixed paraffin-embedded canine mammary gland tissues (34 carcinoma, 14 adenoma, and 11 normal). Using a digital PCR assay, the ErbB2 copy number in these samples was determined as compared to a reference gene on canine chromosome 8. ErbB2 CNG was detected in 14/34 (41%) carcinomas and 2/14 (14%) adenomas. ErbB2 overexpression was observed in 3/34 (9%) carcinomas but not in adenomas. Neither ErbB2 CNG nor ErbB2 overexpression were detected in the normal controls. There was no significant association of the ErbB2 CNG with histological and clinical characteristics such as age, neutered status, histological grade, tumor size, lymph node involvement, distant metastasis, and clinical stage in the dogs with mammary carcinoma. The presence of ErbB2 CNG, but not ErbB2 overexpression, was significantly related to the shorter overall survival. These findings suggest that ErbB2 CNG is a prognostic factor in dogs with mammary carcinoma.

Podoplanin is expressed in various human tumors where it promotes tumor progression, epithelial-mesenchymal transition, and distant metastasis. Podoplanin is also expressed in cancer-associated fibroblasts and induces tumor malignancy. The objective of this study was to evaluate podoplanin expression in various types of feline tumor tissues. Immunohistochemical analysis revealed that podoplanin was expressed in cells of 13/15 (87%) squamous cell carcinomas and 5/19 (26%) fibrosarcomas. Moreover, cancer-associated fibroblasts expressed podoplanin in most tumor types, including 18/21 (86%) mammary adenocarcinoma tissues. Our findings demonstrate that various types of feline tumor tissues expressed podoplanin, indicating the importance of the comparative aspects of podoplanin expression, which may be used as a novel research model for podoplanin biology.

Among 113 feline gastrointestinal epithelial tumors diagnosed between 2006 and 2019, 78 (69%) were detected in the colorectum. Fifty colorectal tumors were selected for further pathological evaluations, of which 9 (18%) were histopathologically diagnosed as adenomas and 41 (82%) as carcinoma. The carcinomas included 33 tubular adenocarcinomas (TAC), 5 tubulovillous adenocarcinomas (TVAC), 2 mucinous adenocarcinomas, and 1 undifferentiated carcinoma. Histopathologically, TAC frequently showed vascular invasion (17/33 cases, 52%). In TAC cases, serosal infiltration (13/15 cases, 87%) and lymph node metastasis (8/9 cases, 89%) were common in bowel resection and lymphadenectomy samples, respectively. Immunohistochemically, the tumor cells of most cases were positive for cytokeratin (CK) 20 (50/50 cases, 100%) and CDX2 (48/50 cases, 96%). Focal immunopositivity for CD10 (11/50 cases, 22%) and CK7 (15/50 cases, 30%) was observed irrespective of the histological subtype. Only a few cases showed diffuse nuclear accumulation of β-catenin (2/50 cases, 4%) and p53 (5/50 cases, 10%). A lack of tubule formation, female sex, and low CDX2 labeling were statistically associated with carcinoma compared to adenoma (ρ = 0.615, P < .001; ρ = 0.279, P = .050; and ρ = −0.265, P = .063, respectively). Other features, including mucin profiles, Ki67 labeling index, and accumulation of β-catenin and p53, were not associated with malignancy. A sequence analysis revealed KRAS mutations in 3/7 TAC cases. These results suggest that KRAS mutations—rather than excessive Wnt/β-catenin signaling and the inactivation of TP53—contribute to the tumorigenesis of feline colorectal carcinoma.

Regulatory T cells may serve as targets in cancer immunotherapy. A previous study showed that the chemokine CCL17 and the receptor CCR4 play roles in regulatory T cell recruitment in canine urothelial carcinoma. In this article, we show that the BRAFV595E mutation is associated with tumor-produced CCL17 and regulatory T cell infiltration in dogs with urothelial carcinoma. In comparison with healthy dogs, dogs with urothelial carcinoma showed increased CCL17 mRNA expression in the bladder and elevated CCL17 protein concentration in urine. Immunohistochemistry showed increased levels of Foxp3+ regulatory T cells in the tumor tissues of urothelial carcinoma. The density of Foxp3+ regulatory T cells was positively correlated with CCL17 concentration in urine, indicating that CCL17 is involved in regulatory T cell recruitment. Moreover, tumor-infiltrating regulatory T cells and urine CCL17 concentration were associated with poor prognosis in dogs with urothelial carcinoma. The number of tumor-infiltrating regulatory T cells, CCL17 mRNA expression, and urine CCL17 concentration in cases with BRAFV595E mutation were higher than those in cases with wild-type BRAF. In vitro, high CCL17 production was detected in a canine urothelial carcinoma cell line with BRAFV595E mutation but not in an urothelial carcinoma cell line with wild-type BRAF. Dabrafenib, a BRAF inhibitor, decreased CCL17 production in the cell line with BRAFV595E mutation. These results suggest that BRAFV595E mutation induced CCL17 production and contributed to regulatory T cell recruitment in canine urothelial carcinoma.

Histiocytic sarcoma (HS) is a haematopoietic tumour of histiocyte origin that has been sporadically reported in four-toed hedgehogs (Atelerix albiventris). The present study aimed to investigate clinical, gross, histopathological and immunohistochemical features of HS in eight hedgehogs. Histological and immunohistochemical features of normal histiocytes and Langerhans cells (LCs) of hedgehogs were also investigated. HLA-DR-, Iba-1- and E-cadherin-positive LCs were observed in the epidermis, while Iba-1- and CD204-positive histiocytes were detected in the lymph nodes and spleen of normal hedgehogs. Localized HS (six cases) developed in the skin and spleen, while disseminated HS (two cases) occurred in the intestine. Tumour cells of disseminated HS were also distributed within the mesenteric lymph nodes, liver, kidney, spleen, lung and adrenal glands. Tumour cells of both localized and disseminated HS were composed of histiocytic cells, spindle to pleomorphic cells, multinucleated giant cells and erythrophagocytic cells. Most tumour cells were immunopositive for Iba-1, CD204 and lysozyme. A small number of tumour cells were positive for E-cadherin and CD208, and the tumour cells in one case were positive for HLA-DR. These results suggest that the tumour cells have variable features of histiocyte origin, including dendritic cells, LCs and macrophages. The behaviour of HS in the hedgehog was very aggressive, and 50% of cases died within 90 days of resection. The present study also highlighted the tendency for local tumour recurrence in localized cutaneous HS cases, suggesting a requirement for a long-term follow-up after excision.

A 4-month-old female mixed-breed cat showed gait disturbance and eventual dysstasia with intention tremor and died at 14 months of age. Postmortem histological analysis revealed degeneration of neuronal cells, alveolar epithelial cells, hepatocytes, and renal tubular epithelial cells. Infiltration of macrophages was observed in the nervous system and visceral organs. The cytoplasm of neuronal cells was filled with Luxol fast blue (LFB)-negative and periodic acid-Schiff (PAS)-negative granules, and the cytoplasm of macrophages was LFB-positive and PAS-negative. Ultrastructurally, concentric deposits were observed in the brain and visceral organs. Genetic and biochemical analysis revealed a nonsense mutation (c.1017G>A) in the SMPD1 gene, a decrease of SMPD1 mRNA expression, and reduced acid sphingomyelinase immunoreactivity. Therefore, this cat was diagnosed as having Niemann-Pick disease with a mutation in the SMPD1 gene, a syndrome analogous to human Niemann-Pick disease type A.

The prevention of age-related memory decline and dementia has been becoming a high priority because of the rapid growth in aging populations. Accumulating epidemiological and clinical studies indicate that intake of fermented dairy products rich in β-lactolin improves memory retrieval and executive function and attenuates cognitive decline in the elderly. However, the effects of long-term consumption of β-lactolin on Alzheimer’s disease (AD) pathologies have not been investigated. In the present study, we examined the effects of β-lactolin and whey digestion rich in β-lactolin on AD pathology in 5×FAD transgenic mice and PS19 tauopathy mice. Intake of β-lactolin and whey digestion rich in β-lactolin reduced the levels of inflammatory cytokines, suppressed the infiltration of activated microglia, decreased the levels of amyloid-β, ameliorated impaired long-term object memory, and attenuated decreased synaptophysin, dopamine, brain-derived neurotrophic factor, and insulin-like growth factor 1 levels in the cortex in 5×FAD transgenic mice. In addition, intake of β-lactolin and whey digestion rich in β-lactolin improved behavioral abnormality and reduced the ratio of phosphorylated tau to total tau in the cortex in PS19 tauopathy mice. These findings indicate that consumption with β-lactolin and whey digestion rich in β-lactolin suppresses inflammation and attenuates AD pathology and cognitive impairment.

To clarify the prevalence of canine intracranial tumors in Japan, a retrospective study was performed using data on 186 canine intracranial tumors. Of 186 cases, 159 cases (85.5%) were primary and 27 cases (14.5%) were secondary intracranial tumors. Among primary intracranial tumors, meningioma (50.9%) was the most common, followed by glial tumors (21.4%) and primary intracranial histiocytic sarcoma (12.6%). These 3 tumors were most frequently found in middle-aged to elderly dogs without any sex predilection. Regarding glial tumors, the incidence of oligodendroglial tumors (79.4%) was higher than that of astrocytic tumors (17.6%). A significant breed predisposition (P

Duchenne muscular dystrophy (DMD) is a progressive muscular disorder caused by X-chromosomal DMD gene mutations. Recently, a new CRISPR/Cas9-mediated DMD rat model (cDMDR) was established and is expected to show cardiac lesions similar to those in humans. We therefore investigated the pathological and pathophysiological features of the cardiac lesions and their progression in cDMDR. For our cDMDR, Dmd-mutated rats (W-Dmd em1Kykn ) were obtained. Dmd heterozygous-deficient females and wild-type (WT) males were mated, and male offspring including WT as controls were used. (1) Hearts were collected at 3, 5, and 10 months of age, and HE- and Masson's trichrome-stained specimens were observed. (2) Electrocardiogram (ECG) recordings were made and analyzed at 3, 5, and 8 months of age. (3) Echocardiography was performed at 9 months of age. In cDMDR rats, (1) degeneration/necrosis of cardiomyocytes and myocardial fibrosis prominent in the right ventricular wall and the outer layer of the left ventricular wall were observed. Fibrosis became more prominent with aging. (2) Lower P wave amplitudes and greater R wave amplitudes were detected. PR intervals tended to be shorter. QT intervals were longer at 3 months but tended to be shorter at 8 months. Sinus irregularity and premature ventricular contraction were observed at 8 months. (3) Echocardiography indicated myocardial sclerosis and a tendency of systolic dysfunction. Pathological and pathophysiological changes occurred in cDMDR rat hearts and progressed with aging, which is, to some extent, similar to what occurs in humans. Thus, cDMDR could be a valuable model for studying cardiology of human DMD.

Human enteropathy-associated T-cell lymphoma (EATL) is considered to be derived from intraepithelial lymphocytes (IELs); however, the origin of canine intestinal T-cell lymphoma (ITCL) remains unclear. Histological, immunohistochemical, and clonality examinations were performed using endoscopically collected canine duodenum samples of mucosal lesions of chronic enteropathy (CE; 73 cases) and ITCL without transmural neoplastic mass lesions (64 cases). Histopathological examinations revealed the intraepithelial accumulation of lymphocytes (called “intraepithelial lymphocytosis”) in 54/73 CE cases (74%) and the epitheliotropism of neoplastic lymphocytes in 63/64 ITCL cases (98%). Immunohistochemically, IELs in CE with intraepithelial lymphocytosis (IEL+CE) were diffusely immunopositive for CD3, with scattered immunopositivity for CD5, CD8, CD20, and granzyme B (GRB). The percentage of CD8+ in CD3+ IELs was significantly lower in IEL+CE than in CE without intraepithelial lymphocytosis (IEL−CE). Double-labeling immunohistochemistry revealed a high percentage of GRB expression in CD8− IEL among IEL+CE. Among 64 ITCL cases, CD3 was immunopositive in 64 (100%), CD5 in 22 (34%), CD8 in 8 (13%), CD20 in 12 (19%), CD30 in 13 (20%), and GRB in 49 (77%). In CD3+ cells, Ki67 immunopositivity was highest in ITCL, intermediate in IEL+CE, and lower in IEL−CE. A clonal TCR gene rearrangement was detected in 1/19 IEL−CE cases (5%), 15/54 IEL+CE (28%), and 38/58 ITCL (66%). These results indicate that the immunophenotype of canine ITCL (CD8−GRB+) is similar to that of the increased IELs in CE. The high proliferative activity and clonality of T cells in IEL+CE suggest that canine ITCL originates from these IELs, similar to human EATL.

Simple Summary This study on the gallbladders and livers of 219 client-owned dogs provides a benchmark for future studies on chronic canine cholecystitis. The statistical evaluation of clinical data; histopathology; histochemistry; and immunohistochemistry in this report provides insight into the etiology of chronic cholecystitis in dogs Abstract (1) Background: Chronic cholecystitis of dogs has not been vigorously investigated histopathologically. In addition, the relationship between gallbladder and liver diseases is not known. (2) Methods: We aimed to provide a hallmark for canine chronic cholecystitis using clinical data, histopathology, histochemistry, immunohistochemistry, and statistical analysis. (3) Results: Our investigation of 219 ultrasonographically abnormal surgically resected canine gallbladders revealed 189 cases (86.3%) of mucosal lymphoplasmacytic infiltration (chronic cholecystitis). Sludge, a gravity-dependent or nondependent fine granular hyperechoic material, was more prevalent (105/219, 47.9%) than mucocele (51/219, 23.2%) in this cohort. Mucosal lymphoid follicles were detected in 68/219 cases (31%), suggesting the influence of long-standing antigenic stimulation. Bacteria were histochemically detected in 41/60 (68.3%) of heavily inflamed gallbladders, 18/129 (14%) of lightly inflamed, and 3/18 (16.7%) of uninflamed gallbladders, suggesting a possible relationship between bacteria and chronic cholecystitis. Simultaneous liver biopsies revealed mild or no inflammation, changes consistent with primary portal vein hypoplasia, and mild hepatocellular degeneration. (4) Conclusions: Based on the results of our statistical analysis, we conclude that canine chronic cholecystitis is a long-standing inflammatory process of unknown (but possibly bacterial) etiology and that liver pathology is unlikely the cause of chronic cholecystitis in dogs.

A two-year-and-eleven-month-old male Shikoku Inu was referred for evaluation of progressive gait abnormality that had begun three months prior. Neurological examination revealed ventral flexion of the neck, a wide-based stance in the hindlimb, wide excursions of the head from side to side, tremor in all four limbs, hypermetria in all four limbs, proprioceptive deficits in all four limbs, reduced patellar reflex in both hindlimbs, and postural vertical nystagmus. Later, behavioral and cognitive dysfunction, ataxia, and visual deficits slowly progressed. Magnetic resonance imaging revealed symmetrical progressive atrophy of the whole brain and cervical spinal cord. Bilateral retinal degeneration was observed, and both flush and flicker electroretinograms were bilaterally non-recordable at the age of five years and eight months, and the dog was euthanized. Histopathologically, faint-to-moderate deposition of light-brown pigments was frequently observed in the cytoplasm of neurons throughout the cerebrum, cerebellum, and nuclei of the brainstem. The pigments were positive for Luxol fast blue, periodic acid–Schiff, and Sudan black B, and exhibited autofluorescence. Electron microscopic examination revealed the accumulation of membranous material deposition in the neuronal cytoplasm. Small foci of pigment-containing macrophages were frequently observed around the capillary vessels. Based on these clinical and pathological findings, the animal was diagnosed with adult-onset neuronal ceroid lipofuscinosis.

With the rapid increase in aging populations worldwide, there has been an increase in demand for preventive and therapeutic measures for age-related cognitive decline and dementia. Epidemiological studies show that consumption of dairy products reduces the risk for cognitive decline and dementia in the elderly. We have previously demonstrated in randomized trials that the consumption of β-lactolin, a whey-derived Gly-Thr-Trp-Tyr lactotetrapeptide, improves cognitive function in older adults. Orally administered β-lactolin is delivered to the brain and inhibits monoamine oxidase, resulting in alleviation of memory impairment. However, there is currently no evidence of the effects of long-term β-lactolin intake on aging. Here, we found that the discrimination index in the novel object recognition test for object recognition memory was reduced in mice aged 20 months compared with that in young mice, indicating that age-related cognitive decline was induced in the aged mice; in aged mice fed β-lactolin for 3 months, memory impairment was subsequently alleviated. In aged mice, impairment of light/dark activity cycles was found to be induced, which was subsequently alleviated by β-lactolin consumption. Additionally, the number of activated microglia in the hippocampus and cortex and the production of cytokines (tumor necrosis factor-α, macrophage inflammatory protein-1α, and macrophage chemoattractant protein-1) were increased in aged mice compared with those in young mice but were reduced in aged mice fed β-lactolin. The age-related hippocampal atrophy was improved in aged mice fed β-lactolin. Cytochrome c levels in the hippocampus and cortex were increased in aged mice compared with those in young mice but were also reduced by β-lactolin consumption. These results suggest that β-lactolin consumption prevents neural inflammation and alleviates aging-related cognitive decline.

To elucidate the histopathological characteristics and immunophenotypes of canine transmural “mass-forming” gastrointestinal lymphomas and plasmacytomas, 83 surgically resected biopsy samples were examined. All lymphomas and plasmacytomas were located in the small or large intestine except for 1 plasmacytoma which was in the stomach. According to the World Health Organization (WHO) classification, B-cell neoplasms (17 cases) included lymphoplasmacytic lymphoma (6/17), plasmacytoma (5/17), follicular lymphoma (3/17), and diffuse large B-cell lymphoma (3/17). Based on nuclear sizes, T-cell neoplasms (66 cases) were broadly divided into large cell lymphoma (LCL; 48/66) and small cell lymphoma (SCL; 18/66). According to the WHO classification, T-cell neoplasms included anaplastic large T-cell lymphoma (ALCL; 10/66), angiotropic T-cell lymphoma (3/66), mixed inflammatory type peripheral T-cell lymphoma (mixed inflammatory type PTCL; 33/66), and PTCL-not otherwise specified (PTCL-NOS; 20/66). Mixed inflammatory type PTCLs were further divided into histiocyte- (27/33) and eosinophil- (6/33) dominant types. Immunohistochemically, lymphoplasmacytic lymphomas were positive for Pax5 (6/6) and IgM (5/6), while plasmacytomas were positive for IgG (5/6) and negative for Pax5. LCLs were immunopositive for granzyme B in 31/48 cases (65%) and CD8 in 9/48 cases (19%), while SCLs were immunopositive for granzyme B in 3/18 cases (17%) and CD8 in 3/18 cases (17%). Furthermore, 8/10 cases (80%) of ALCL and 19/27 cases (70%) of histiocyte-dominant PTCL were immunopositive for granzyme B, whereas 6/20 cases (30%) of PTCL-NOS, 1/6 cases (17%) of eosinophil-dominant PTCL, and no cases of angiotropic T-cell lymphomas were immunopositive for granzyme B. The present study describes the immunophenotypes in different histological types of transmural gastrointestinal lymphomas in the dog.

Epilepsy surgery is a common therapeutic option in humans with drug-resistant epilepsy. However, there are few reports of intracranial epilepsy surgery for naturally occurring epilepsy in veterinary medicine. A 12-year-old neutered male domestic shorthair cat with presumed congenital cortical abnormalities (atrophy) in the right temporo-occipital cortex and hippocampus had been affected with epilepsy from 3 months of age. In addition to recurrent epileptic seizures, the cat exhibited cognitive dysfunction, bilateral blindness, and right forebrain signs. Seizures had been partially controlled (approximately 0.3–0.7 seizures per month) by phenobarbital, zonisamide, diazepam, and gabapentin until 10 years of age; however, they gradually became uncontrollable (approximately 2–3 seizures per month). In order to plan epilepsy surgery, presurgical evaluations including advanced structural magnetic resonance imaging and long-term intracranial video-electroencephalography monitoring were conducted to identify the epileptogenic zone. The epileptogenic zone was suspected in the right atrophied temporo-occipital cortex and hippocampus. Two-step surgery was planned, and a focal cortical resection of that area was performed initially. After the first surgery, seizures were not observed for 2 months, but they then recurred. The second surgery was performed to remove the right atrophic hippocampus and extended area of the right cortex, which showed spikes on intraoperative electrocorticography. After the second operation, although epileptogenic spikes remained in the contralateral occipital lobe, which was suspected as the second epileptogenic focus, seizure frequency decreased to

Although pyloric and duodenal adenomas occasionally occur in cats, limited information is currently available on their phenotypes and molecular features. The present study investigated the pathological features of these tumors and the mechanisms underlying their tumorigenesis. Biopsy samples from 8 cats diagnosed with pyloric or duodenal adenomas were examined by histopathology and immunohistochemistry. Normal pyloric and duodenal tissues of cats were assessed for comparison. All cases showed a papillary growth of cuboidal to columnar cells with eosinophilic, ground-glass cytoplasm. Mucin in tumor cells was positive for periodic acid–Schiff and paradoxical concanavalin-A staining, but was negative for Alcian blue. Immunohistochemically, tumor cells were positive for cytokeratin (CK) 19 in 8/8 cases and for CK20 in 5/8 cases, and weakly positive for CD10 in 4/8 cases, CK7 in 3/8 cases, and β-catenin in 2/8 cases. Nuclear accumulation of p53 was not detected in any case. DNA sequencing analysis identified no KRAS or GNAS mutations in the 4/8 cases and 5/8 cases for which the KRAS and GNAS genes could be amplified. The histological and immunohistochemical features of tumor cells were similar to those of mucous neck cells and the pyloric gland of normal feline tissue. The morphology of feline pyloric and duodenal adenomas was consistent with that of pyloric gland adenoma in humans; however, its molecular pathogenesis may differ given the lack of KRAS and GNAS mutations in the feline tumors.

The protective property of propolis across a wide spectrum of diseases has long been realized, yet the anti-tumor efficacy of this bioactive substance from Philippine stingless bees has remained poorly understood. Here, we showed the tumor-suppressing potential of crude ethanolic extract of Philippine stingless bee propolis (EEP) in in vitro models of gastric cancer highlighting the first indication of remarkable subtype specificity towards differentiated-type human gastric cancer cell lines but not the diffuse-type. Mechanistically, this involved the profound modulation of several cell cycle related gene transcripts, which correlated with the prominent cell cycle arrest at the G0/G1 phase. To reinforce our data, a unique differentiated-type gastric cancer model, A4gnt KO mice, together with age-matched 60 week-old C57BL/6 J mice were randomly assigned to treatment groups receiving distilled water or EEP for 30 consecutive days. EEP treatment induced significant regression of gross and histological lesions of gastric pyloric tumors that consistently corresponded with specific transcriptional regulation of cell cycle components. Also, the considerable p21 protein expression coupled with a marked reduction in rapidly dividing BrdU-labeled S-phase cells unequivocally supported our observation. Altogether, these findings support the role of Philippine stingless bee propolis as a promising adjunct treatment option in differentiated-type gastric cancer.

This retrospective study of a series of 18 cases aimed to describe the clinical and pathological findings of oral tumours in rabbits, as there have been few reports detailing spontaneous oral tumours in this species. A total of 13 different tumour types were diagnosed: squamous cell carcinoma (three), ameloblastoma (two), fibrosarcoma (two), osteosarcoma (two), cementoma (one), complex odontoma (one), giant cell epulis (one), sarcoma (one), chondrosarcoma (one), trichoepithelioma (one), papilloma (one), malignant melanoma (one) and basal cell carcinoma (one). Odontogenic tumours were relatively common in this study as compared to the oral tumours typically identified in dogs and cats. The most common clinical sign in this study was feeding abnormalities. Surgical excision and radiation therapy were found to be effective in rabbits.

Objectives Primary copper-associated hepatopathy (PCH) has been reported in young cats. Although our group recently reported a young cat with PCH harbouring single-nucleotide variations in ATP7B, limited information is available regarding its association with the pathogenesis of feline PCH. The objective of this study was to investigate the prevalence of ATP7B variations in cats with PCH. Methods Rhodanine staining was performed to detect hepatic copper accumulation (HCA) in intraoperative liver tissue specimens from 54 cats. In cats with HCA, variations in ATP7B and COMMD1 and serum ceruloplasmin activity were analysed. Results Based on age, liver histopathological findings and hepatic distribution of accumulated copper, PCH was suspected in 4/54 cats. Sequence analysis of ATP7B and COMMD1 revealed single-nucleotide variations in ATP7B in 3/4 cats with PCH. Among the cats with PCH, one showed remarkably low serum ceruloplasmin activity, while the other three did not. Conclusions and relevance The results of this study suggest that some cats with PCH harbour single-nucleotide variations in ATP7B, suggesting that feline PCH is an equivalent disorder to human Wilson’s disease. This study provides basic evidence facilitating further studies of the pathophysiology and treatment of feline PCH.

Aquaporin-2 (AQP2), a vasopressin-regulated water channel, plays an important role in renal water homeostasis. It has been reported that the level of AQP2 in human urine is altered during pregnancy. However, little is known about the level of urinary AQP2 in pregnant cattle. In this study, we examined the level of AQP2-bearing extracellular vesicles (uEV-AQP2), which account for most urinary AQP2, in both heifers and cows during the gestational and postpartum periods. The level of uEV-AQP2 was significantly decreased during gestation in comparison with the other cattle examined. Similarly, the levels of EV marker proteins in uEVs, including tumor susceptibility gene 101 (TSG101) protein and apoptosis-linked gene 2-interacting protein X (ALIX), were significantly decreased during gestation. There were significant correlations between the levels of uEV-AQP2 and uEV-TSG101, or uEV-ALIX. Immunohistochemistry data from pregnant and non-pregnant cattle supported the notion that the level of uEV-AQP2 was decreased during gestation. These data indicate that the level of uEV-AQP2 is decreased in pregnant cattle, possibly through a decrease in both the number of EVs released into the urine and renal AQP2 expression.

Canine histiocytic sarcoma (HS) is an aggressive tumor type originating from dendritic cells or macrophages. We previously reported high incidence of the two-base (AT) insertion mutation (insAT) in the tumor protein p53 (TP53) gene in dogs with HS, and the aim of this study was to investigate the clinical significance of insAT in canine HS. The present study established a sensitive digital PCR-based assay for detecting insAT and examined its associations with clinical variables and survival time. The mutation was detected in 26 of 64 dogs (41%), and the mean mutant allele frequency was 1.9% (range, 0.014-35%), indicating that not all tumor cells harbor insAT. The incidence of insAT was significantly higher in dogs with metastatic lesions than in those without metastatic lesions. However, the existence of insAT was not associated with survival time or response to chemotherapy with lomustine or nimustine. This study suggested that HS cells might acquire insAT in the TP53 gene during development of metastasis, but insAT was not a prognostic factor in canine HS. Further studies are needed to investigate the contribution of insAT to the development of metastatic lesions of canine HS.

The rapid growth in aging populations has made prevention of age-related memory decline and dementia a high priority. Several epidemiological and clinical studies have concluded that fermented dairy products can help prevent cognitive decline; furthermore, intake of Camembert cheese prevents microglial inflammation and Alzheimer’s pathology in mouse models. To elucidate the molecular mechanisms underlying the preventive effects of fermented dairy products, we screened peptides from digested milk protein for their potential to regulate the activation of microglia. We identified dipeptides of tryptophan–tyrosine (WY) and tryptophan–methionine that suppressed the microglial inflammatory response and enhanced the phagocytosis of amyloid-β (Aβ). Various fermented dairy products and food materials contain the WY peptide. Orally administered WY peptide was smoothly absorbed into blood, delivered to the brain, and improved the cognitive decline induced by lipopolysaccharide via the suppression of inflammation. Intake of the WY peptide prevented microglial inflammation, hippocampal long-term potential deficit, and memory impairment in aged mice. In an Alzheimer’s model using 5×FAD mice, intake of the WY peptide also suppressed microglial inflammation and accumulation of Aβ, which improved cognitive decline. The identified dipeptides regulating microglial activity could potentially be used to prevent cognitive decline and dementia related to inflammation.

A 7‐year‐old neutered female domestic shorthaired cat born in Poland and then moved to Japan presented to the local clinic with recent onset of convulsive cluster seizures and status epilepticus. Magnetic resonance imaging revealed bilateral swelling of the hippocampus with T2 hyperintensity and contrast enhancing image, suggesting hippocampal necrosis. The cat completely recovered after treatment with antiepileptic drugs (AED) and administration of prednisolone (1 mg/kg PO q24h for 4 days and tapered). However, cluster seizures reoccurred and developed into status epilepticus despite increasing doses of AED. Although the convulsions were resolved by other AEDs, stupor and renal failure developed, and the cat was euthanized. Pathological findings were consistent with hippocampal necrosis. Immunological analysis for leucine‐rich glioma inactivated 1 (LGI1) autoantibodies was negative, but antibodies against DCC (deleted in colorectal carcinoma) known as netrin‐1 receptor were found. This report describes a case of feline autoimmune limbic encephalitis and hippocampal necrosis that were presumably associated with DCC autoantibodies.

An 11-year-old castrated male Chihuahua dog was presented with complaints of polyuria, polydipsia, abdominal enlargement, and alopecia. Hyperadrenocorticism was diagnosed on the basis of clinical signs, blood tests, adrenocorticotropin-stimulation test results, and an elevated serum adrenocorticotropin concentration. Contrast-enhanced magnetic resonance imaging showed that the pituitary gland was enlarged, compatible with a pituitary macroadenoma. Pituitary-dependent hyperadrenocorticism was suspected, and transsphenoidal hypophysectomy was thus performed for complete resection of the tumor. After surgery, the serum adrenocorticotropin concentration normalized and the hyperadrenocorticism resolved. Histological and immunocytochemical analyses revealed a benign tumor composed of mature neuronal cells and glial cells, suggestive of a ganglioglioma with immunolabeling for adrenocorticotropin. Careful analysis of the resected tumor revealed no pituitary adenoma tissue. The clinical and histopathologic findings indicated that the ganglioglioma was directly responsible for the hyperadrenocorticism. This is the first case of hyperadrenocorticism caused by a ganglioglioma in a dog.

Summary Twenty-two newborn puppies that did not receive colostrum exhibited acute respiratory signs and died at a breeding facility. Pathological examinations were performed on four of the puppies. At necropsy examination, the lungs were firm and mottled dark red, consistent with acute bronchopneumonia. Histopathologically, there was marked infiltration of neutrophils and macrophages into the bronchi and alveoli, and gram-negative coccobacilli were attached diffusely to the cilia of bronchial mucosa. Immunohistochemistry for Bordetella bronchiseptica antigen revealed positive labelling of the bacterial agents. On electron microscopy, a large number of coccobacilli were observed attaching to the cilia of bronchial epithelial cells. Real-time polymerase chain reaction amplified a B. bronchiseptica gene from the affected lung tissue. Based on these findings, the four puppies were diagnosed with fatal B. bronchiseptica bronchopneumonia.

The mutations of TP53 gene are frequently observed in canine histiocytic sarcoma (HS). The objective of this study was to examine the distribution of tumor cells with TP53 gene mutations. Tumor tissues were divided into three or four regions and TP53 gene mutations were examined. TP53 gene mutations were detected only in parts of the HS tissues from six of the eight dogs, and the frequency of the mutant allele varied (0-65%) among the tumor regions. This study suggests that canine HS can exhibit intratumor heterogeneity. Further studies are needed to examine the clinical significance of the intratumor heterogeneity of TP53 gene mutations.

Canine anal sac gland carcinoma (ASGC) frequently occurs in the apocrine glands of the canine anal sac and shows aggressive biological behavior. The expression of human epidermal growth factor receptor 2 (HER2) has been reported in various human and canine tumors. HER2 is a promising therapeutic target of these tumors, and HER2-targeted drugs, such as trastuzumab and lapatinib, have improved the outcome of these patients. In this study, HER2 expression in ASGC was evaluated to investigate its potential as a therapeutic target for canine ASGC. HER2 mRNA expression in surgically resected ASGC tissues was significantly higher than that in normal anal sac tissue. To evaluate the expression of HER2 protein, paraffin-embedded ASGC tissues were immunohistochemically evaluated. Strong and broad staining of HER2 was detected in ASGC tissues, while HER2 was weakly to moderately stained in normal anal sac apocrine glands and squamous epithelia. The degree of HER2 expression in ASGC tissues was scored based on its intensity and positivity (score: 0–3+). Scoring of HER2 expression revealed 6 samples (24%) scored 3+, 14 (56%) scored 2+, and 5 (20%) scored 1+, with no samples scoring 0. In all, 80% of canine ASGC tissues were positive for HER2 (scored ≥2+). Furthermore, putative HER2-overexpressed cells in ASGC were detected with trastuzumab by flow cytometry. These preliminary data may lead to further evaluation of the role of HER2 in canine ASGC as a mechanism of malignancy and as a therapeutic target for HER2-targeted therapy.

The present paper describes Felis catus papillomavirus (FcaPV) type 5-associated cutaneous mass in a Domestic Shorthair cat. Histological examination revealed multicentric epidermal acanthosis with papillomavirus-associated cytopathic changes, which progressed to a tumor lobule with intact basement membrane. An association between FcaPV-5 and the cutaneous lesions was confirmed by detection of virus antigen and genes using immunohistochemistry, polymerase chain reaction (PCR), sequencing analysis, and in situ hybridization. Based on these findings, the lesions were diagnosed as FcaPV-5-associated viral plaques and Bowenoid in situ carcinoma (BISC). To date, this is the first reported case of FcaPV-5 infection in a cat in Japan, and the second case reported worldwide. For the first time this papillomavirus type is associated with BISC development.

Papillomavirus (PV) is a well-known pathogen associated with epithelial and mucosal neoplastic diseases. In contrast to human PVs, characterization of animal PVs from the aspect of anogenital neoplasm is still on a learning curve. In the present study, two vulval and one anal warts, histologically diagnosed as fibropapillomas, excised from dairy cattle were analyzed. PCR and sequencing revealed that bovine papillomavirus type 1 (BPV-1) and BPV-2 were detected from anal and vulval fibropapillomas, respectively. Immunohistochemistry detected PV antigen in a few differentiated keratinocytes of one vulval case. Reverse-transcriptase PCR detected the early region, but not the late region of BPV mRNA in all three cases. The present study will provide new insight into the relationship between BPV and anogenital papilloma in cattle.

Objectives To examine the efficacy and adverse events of continuous L-asparaginase administration in dogs with large cell lymphoma of presumed gastrointestinal origin. Methods We retrospectively reviewed medical records of dogs with large cell lymphoma of presumed gastrointestinal origin treated with continuous L-asparaginase administration from 2009 to 2018. We collected information on the signalment, lesion site, complete blood count, serum biochemical profile, diagnostic imaging findings, cytological and histopathological findings, immunophenotype, L-asparaginase administration frequency, treatment response, adverse events, rescue protocol, and patient outcomes. Clinical outcomes were assessed using medical records or by contacting the owner or referring veterinarian. Results Thirty-two dogs with large cell lymphoma of presumed gastrointestinal origin received weekly L-asparaginase administration. The median number of L-asparaginase injections was seven (range: 1-30). Although two of the 32 dogs had gastrointestinal toxicity of grade 3 or higher, none developed a hypersensitivity reaction. The response rate based on ultrasonographic findings was 18/32 (56%) and that based on clinical signs was 30/32 (94%). The median overall progression-free survival was 50 days (range: 2-214 days), and median overall survival was 147 days (range: 2-482 days). Clinical significance Adverse events associated with continuous L-asparaginase administration were rare. Clinical signs at diagnosis improved in most cases. Based on these results, continuous L-asparaginase administration appears to be a reasonable treatment option for dogs with large cell lymphoma of presumed gastrointestinal origin. This article is protected by copyright. All rights reserved.

Meningioma is the most common primary brain tumor in cats, although there are few reports about their pathological features. To investigate the histopathological subtypes and immunohistochemical features including expression of cytokeratin and cell adhesion molecules, 45 cases of feline meningioma were examined. The mean age was 12.5 years (range 6-21 years). No statistically significant sex predilection was observed. Regarding the anatomical location of meningioma, tumors mostly developed in the cerebrum, followed by spinal cord and cerebellum, and multiple meningioma was observed in one cat. Microscopically, linear or focal mineralization was observed in 40 cases and cholesterol cleft was observed in 14 cases. Based on histopathological subtypes, there were 15 fibrous, 22 transitional, 2 meningothelial, 5 atypical, and 1 anaplastic meningiomas. These subtypes are classified into grade 1 (39 cases), grade 2 (5 cases), and grade 3 (1 case). There was no significant difference in the Ki-67 index among histological subtypes or grades. Immunohistochemically, the tumor cells were positive for cytokeratin in 5 cases (12.8%), vimentin in 17 cases (43.6%), E-cadherin in 36 cases (92.3%), β-catenin in 21 cases (53.8%), and N-cadherin in 1 case (2.6%), demonstrating the utility of E-cadherin-immunohistochemistry for the diagnosis of feline meningiomas.

The simultaneous accumulation of multiple pathological proteins, such as hyperphosphorylated tau (hp-tau) and phosphorylated α-synuclein (p-αSyn), has been reported in the brains of patients with various neurodegenerative diseases. We previously demonstrated that hp-tau-dependent p-αSyn accumulation was associated with the activation of GSK-3β in the brains of P301L tau transgenic mice. To confirm the effects of another mutant tau on p-αSyn accumulation in vivo, we herein examined the brains of PS19 mice that overexpress human P301S mutant tau. Immunohistochemically, hp-tau and p-αSyn aggregates were detected in the same neuronal cells in the cerebrum and brain stem of aged PS19 mice. A semiquantitative analysis showed a positive correlation between hp-tau and p-αSyn accumulation. Furthermore, an activated form of GSK-3β was detected within cells containing both hp-tau and p-αSyn aggregates in PS19 mice. Western blotting showed a decrease in inactivated PP2A levels in PS19 mice. The present results suggest that the overexpression of human P301S mutant tau induces p-αSyn accumulation that is accompanied by not only GSK-3β, but also PP2A activation in PS19 mice, and highlight the synergic effects between tau and αSyn in the pathophysiology of neurodegenerative diseases that show the codeposition of tau and αSyn.

Case summary A 14-year 3-month-old spayed female mixed-breed cat presented with jaundice, anaemia and thrombocytopenia. Haemophagocytic syndrome associated with lymphoma was suspected after cytological examination of the spleen. Despite treatment with prednisolone, L-asparaginase and nimustine, the cat died 176 days after the initial presentation. Necropsy revealed splenomegaly and hepatomegaly, without lymphadenopathy. Histopathologically, neoplastic lymphoid cells infiltrated the hepatic sinusoid and splenic sinus. The neoplastic lymphoid cells showed marked hepatocytotropism and contained erythrocytes, which was also confirmed by electron microscopy. Immunohistochemically, neoplastic lymphoid cells were positive for CD3, TIA1 (GMP-17) and granzyme B, and negative for CD8, CD20, CD56, CD57, CD79a and Iba1. Based on these findings, the cat was diagnosed with hepatosplenic T-cell lymphoma (HS-TCL) with hepatocytotropism. Relevance and novel information This case shows cytotoxic immunophenotype of HS-TCL in a cat, which has not been demonstrated before. Severe hepatocytotropism and haemophagocytosis of the neoplastic cells were likely to be associated with jaundice and anaemia, respectively, and the poor outcome of the present case.

A 6-year-old intact female sugar glider (Petaurus breviceps) had a swelling at the pouch region and died 8 days after presentation. At necropsy, the urinary bladder and abdominal lymph nodes were enlarged and a mass was located in the pericloacal region. Tumour infiltration was also observed in the medial iliac lymph nodes, liver, spleen, small intestine, uterus and left ovary. Histopathologically, the tumours were composed of pleomorphic histiocytes that had round or bizarre nuclei and abundant pale eosinophilic cytoplasm. Immunohistochemically, tumour cells were positive for ionized calcium-binding adaptor molecule 1 and human leukocyte antigen and negative for CD3, B lymphocyte antigen 36 and cytokeratin. Histopathological and immunohistochemical examinations confirmed a diagnosis of disseminated histiocytic sarcoma. This neoplasm has not been previously reported in a sugar glider.

Arteriolar lesions with lipid and/or amyloid deposits are frequently detected in canine gonads by routine histopathologic examination; however, they have never been examined in detail. In the present study, a total of 139 testes/epididymides and 200 ovaries from 72 male (4 months to 14 years old) and 105 female (7 months to 16 years old) dogs were examined for arteriolar lesions. Arteriolar lesions were detected in 21 of 72 male dogs (29%) and 54 of 105 female dogs (51%). These lesions were histologically classified into 4 types: “fibromuscular hypertrophy,” characterized by thickening of the tunica intima; “focal vasculitis,” characterized by mononuclear cell infiltration; “vacuolar change,” consisting of lipid accumulation and infiltration of foamy cells; and “hyalinosis,” characterized by irregular thickening with amyloid deposits. In the lesions of vacuolar change and hyalinosis, lipid deposition and infiltration of α-SMA-positive cells and Iba-1-positive cells were also observed. Foamy cells and amyloid deposits were immunopositive for apolipoproteins and oxidized low-density lipoprotein-related proteins. These results indicate that vacuolar change is possibly an early stage of atherosclerosis, and that amyloid may deposit as a consequence of the microenvironment associated with atherogenesis. Logistic regression analysis revealed that arteriolar lesions with lipid deposits were associated with age and interstitial cell tumors in male dogs, and with age in female dogs. Aging is likely an important risk factor of arteriolar lesions with lipid deposits of the canine gonads.

Alzheimer’s disease (AD) is characterized by the accumulation of amyloid-β (Aβ) as senile plaques and cerebral amyloid angiopathy, and hyperphosphorylated tau (hp-tau) as neurofibrillary tangles in the brain. The AD-related pathology has been reported in several non-human animals, and most animals develop only the Aβ or tau pathology. We herein describe the Aβ and hp-tau pathology in the brains of aged pinniped species (seal, sea lion, and walrus). Molecular analyses revealed that the sequence of pinniped Aβ was identical to that of human Aβ. Histopathological examinations detected argyrophilic plaques composed of Aβ associated with dystrophic neurites in the cerebral cortex of aged pinnipeds. Astrogliosis and microglial infiltration were identified around Aβ plaques. Aβ deposits were observed in the blood vessel walls of the meninges and cerebrum. Pinniped tau protein was physiologically subjected to alternative splicing at exons 2, 3, and 10, and presented as five isoforms: two 3-repeat tau isoforms (1N3R, 2N3R) and three 4-repeat tau isoforms (0N4R, 1N4R, 2N4R); 0N3R tau isoform was absent. Histopathological examinations revealed argyrophilic fibrillar aggregates composed of hp-tau in the neuronal somata and neurites of aged pinniped brains. Few hp-tau aggregates were found in oligodendrocytes and microglia. Biochemically, hp-tau of the 3-repeat and 4-repeat isoforms was detected in brain sarkosyl-insoluble fractions. Aβ and hp-tau both predominantly accumulated in the neocortex, particularly the frontal cortex. Furthermore, the activation of GSK-3β was detected within cells containing hp-tau aggregates, and activated GSK-3β was strongly expressed in cases with severe hp-tau pathologies. The present results suggest that, in association with Aβ deposition, the activation of GSK-3β contributes to hp-tau accumulation in pinniped brains. Here, we report that pinniped species naturally accumulate Aβ and tau with aging, similar to the human AD pathology.

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine tumor, and most human MCC cases are infected by Merkel cell polyomavirus (MCPyV). However, the underlying pathogeneses of MCC in animals remain unclear. In the present study, newly established cell lines from feline and canine MCC, a MCPyV-positive human MCC cell line, and MCC tissues from 25 cats and 1 dog were examined and compared pathologically. Feline and canine MCCs were composed of tumor cells arranged in trabeculae and solid packets. Twenty out of 25 feline MCC cases (80%) had other proliferative cutaneous lesions, such as carcinoma in situ and squamous cell carcinoma. Among the 25 feline MCC cases, tumor cells were immunopositive for cytokeratins (CKs), including CK5/6 (4/25 cases, 16%), CK7 (5, 20%), CK18 (25, 100%), CK19 (20, 80%), and CK20 (20, 80%). The tumor cells of feline MCC were also immunopositive for synaptophysin (24/25, 96%) and CD56 (22/25, 88%). The tumor cells of canine MCC were immunopositive for CK18, CK19, CK20, and synaptophysin. Cultured feline and canine MCC cells grew in adherent monolayers and exhibited diffuse cytoplasmic immunoreactivity for CKs, whereas human MCC cells grew in suspension and exhibited dot-like cytoplasmic immunoreactivity for CKs. Differences in the distribution of CKs between human and animal MCC may be attributed to cell adhesion propensities. MCPyV genes and antigen were not detected in feline or canine MCC, suggesting a different etiology from human MCC.

Neonatal encephalopathy with seizures (NEwS) is an epileptic encephalopathy with an autosomal recessive inheritance pattern found in Standard Poodle puppies. The causal genetic variant for NEwS has been identified as a homozygous missense mutation in ATF2 (c.152T>G, p.Met51Arg), and a pathological cerebellar change has been reported. Magnetic resonance imaging showed reduced whole-brain size, dilated ventricles, developmental abnormalities of the white matter of the cerebrum, white matter signal abnormalities in the occipital lobe, and abnormal morphology of the cerebellum. Histopathology included previously unrecognized irregular neuronal migration in the subventricular zone around the lateral ventricles in the frontal lobe and white matter rarefaction especially at the level of the occipital lobe in the cerebrum in addition to the cerebellar cortical dysplasia that has been previously described. The findings of this case may highlight the critical role of ATF2 in neurodevelopmental processes in the canine brain.

Podoplanin (PDPN), a small transmembrane mucin-like glycoprotein, is ectopically expressed on tumor cells. PDPN is known to be linked with several aspects of tumor malignancies in certain types of human and canine tumors. Therefore, it is considered to be a novel therapeutic target. Monoclonal antibodies targeting PDPN expressed in human tumor cells showed obvious anti-tumor effects in preclinical studies using mouse models. Previously, we generated a cancer-specific mouse&ndash, dog chimeric anti-PDPN antibody, P38Bf, which specifically recognizes PDPN expressed in canine tumor cells. In this study, we investigated the safety and anti-tumor effects of P38Bf in preclinical and clinical trials. P38Bf showed dose-dependent antibody-dependent cellular cytotoxicity against canine malignant melanoma cells. In a preclinical trial with one healthy dog, P38Bf administration did not induce adverse effects over approximately 2 months. In phase I/II clinical trials of three dogs with malignant melanoma, one dog vomited, and all dogs had increased serum levels of C-reactive protein, although all adverse effects were grade 1 or 2. Severe adverse effects leading to withdrawal of the clinical trial were not observed. Furthermore, one dog had stable disease with P38Bf injections. This is the first reported clinical trial of anti-PDPN antibody therapy using spontaneously occurring canine tumor models.

Objectives Neoplasms that arise in the nasal cavity are reported infrequently in rabbits. This case series aims to review and determine the clinical behaviour of neoplasms in the nasal cavity in rabbits. Materials and methods A retrospective study was conducted on seven pet rabbits diagnosed with intranasal tumours to describe the clinical and histopathological findings and prognoses after surgery and/or radiotherapy. Results The most common clinical signs were nasal snoring when breathing, nasal discharge, and subsequent dyspnoea and anorexia. Six different histopathological types of tumours were diagnosed: intranasal adenocarcinoma, squamous cell carcinoma, osteosarcoma, carcinoid tumour, osteoma, and lymphoma. Skull radiography only revealed the abnormalities in three of seven cases but on CT, the intranasal masses were more clearly identified in all cases. All cases received tumour resection through rhinostomy and four cases received radiotherapy after surgery. In the six cases with a known outcome, the survival time after surgery was more than 13 months. Clinical significance This case series provides an insight of the behavior of intranasal neoplasms in rabbits. Surgical treatment and radiotherapy could improve their clinical sings.