Congenital malformation of the vaginal orifice,imperforate vagina,in the common marmoset (Callithrix jacchus)

The following is a report on a congenital vaginal malformation, imperforate vagina, in the common marmoset (Callithrix jacchus). This anomaly was observed for the first time in an adult female in our research colony. There was no uterine and vaginal aplasia or atresia in her grossly normal genital tract. The plasma progesterone concentration suggested that the ovarian cycle had ceased. However, this may not be related to a functional anomaly, but rather to suppressed ovulation resulting from subordination to cagemates considering the various stages of follicular development observed.     

Spontaneous Malignant T-cell Lymphoma in a Young Adult Crl:CD (SD) Rat

We investigated a case of spontaneous malignant T-cell lymphoma observed in a 19-week-old male Crl:CD (SD) rat. The rat showed paralysis beginning 1 week before euthanasia. Hematological examination revealed marked lymphocytosis without distinct atypia. Macroscopically, hepatosplenomegaly and partial atrophy of the thoracic spinal cord were observed. Microscopically, neoplastic cells infiltrated into the liver, splenic red pulp, bone marrow and epidural space of the thoracic spinal cord, while no neoplastic cells were observed in the thymus and lymph nodes. Moreover, the spinal cord showed focal degeneration due to compression by marked infiltration of neoplastic cells in the subdural space. The neoplastic cells were generally small-sized round cells that had a round nucleus with/without a single nucleolus and scanty cytoplasm. Immunohistochemically, the neoplastic cells were positive for CD3 and CD8 and negative for CD79α. Judging from these results, the present tumor in this young adult rat was diagnosed as malignant T-cell lymphoma.     

Pharmacokinetics and effects on clinical and physiological parameters following a single bolus dose of propofol in common marmosets (Callithrix jacchus)

The objectives of this study were (a) to establish a population pharmacokinetic model and (b) to investigate the clinical and physiological effects of a single bolus dose of propofol in common marmosets. In Study 1, pharmacokinetic analysis was performed in six marmosets under sevoflurane anaesthesia. 8 mg/kg of propofol was administrated at a rate of 4 mg kg^?1 min^?1. Blood samples were collected 2, 5, 15, 30, 60, 90, 120 or 180 min after starting propofol administration. Plasma concentration was measured, and population pharmacokinetic modelling was performed. A two‐compartment model was selected as the final model. The population pharmacokinetic parameters were as follows: V₁ = 1.14 L, V₂ = 77.6 L, CL₁ = 0.00182 L/min, CL₂ = 0.0461 L/min. In Study 2, clinical and physiological parameters were assessed and recorded every 2 min after 12 mg/kg of propofol was administrated at a rate of 4 mg kg^?1 min^?1. Immobilization was sustained for 5 min following propofol administration without apparent bradycardia. While combination of propofol and sevoflurane caused apnoea in Study 1, apnoea was not observed following single administration of propofol in Study 2. These data provide bases for further investigation on intravenous anaesthesia using propofol in common marmosets.     

A case of nontraumatic gas gangrene in a common marmoset (Callithrix jacchus)

The common marmoset is widely used in neuroscience and regenerative medicine research. However, information concerning common marmoset disorders, particularly infectious diseases, is scarce. Here, we report a case of a female common marmoset that died suddenly due to gas gangrene. The animal presented with gaseous abdominal distention at postmortem, and Clostridium perfringens type A was isolated from several tissues. Vacuoles, a Gram-positive bacteremia and intravascular hemolysis were observed microscopically in the muscles, liver and lungs. On the basis of these findings, we diagnosed nontraumatic gas gangrene caused by Clostridium perfringens type A in this common marmoset.     

Spontaneous Rhabdomyosarcoma in a Common Marmoset ( Callithrix jacchus )

The common marmoset (Callithrix jacchus) is now widely used in various research fields, including toxicology. However, information about the background pathology of this species is scarce. Here, we report a case of rhabdomyosarcoma that spontaneously occurred in a common marmoset. A 44-month-old male common marmoset was euthanized due to bilateral hind limb paralysis. At necropsy, a 2×2×5-cm intramuscular mass was observed in the lower right back. Histologically, the mass was mainly composed of interlacing bundles of spindle-shaped tumor cells. Immunohistochemically, the tumor cells were positive for myogenin, desmin, vimentin and alpha-smooth muscle actin. Ultrastructurally, the tumor cells contained bundles of myofilaments with Z-band-like structures. Thus, the tumor was diagnosed as a rhabdomyosarcoma. To our knowledge, this is the first report of spontaneous rhabdomyosarcoma that was definitely diagnosed in the common marmoset.     

Spontaneous seminoma in medaka (Oryzias latipes)

Although spontaneous development of seminoma is rare in medaka, we encountered spontaneous testicular tumors located within the abdominal cavity in two adult medakas. The growth patterns of the tumors were a combination of solid and cord arrangements in one of the two cases (Case I) and lobular in the other case (Case II). The tumor cells resembled the cells at different stages of spermatogenesis, and a small number of oocyte-like cells were also scattered within the tumor. The tumor with solid and cord patterns showed loss of normal testicular architecture, and the tumor cells had partly invaded the dorsal muscular tissue and metastasized to the liver, kidney, and eye. The tumor with a lobular pattern did not exhibit local invasion or metastasis. The tumors were diagnosed as seminomas based on their histopathological characteristics, and the tumor in Case I was observed to be more malignant than that in Case II.     

Fatal lymphoproliferative disease in a common marmoset (Callithrix jacchus) following inoculation of Ag876 strain of Epstein-Barr virus and a tumor-promoting agent: Preliminary report

We report here the development of a fatal lymphoproliferative disease in a common marmoset (Callithrix jacchus) following inoculation of the Ag876 strain of Epstein-Barr virus (EBV) and of the tumor promoting agent 12-O-tetradecanoylphorbol-13-acetate (TPA). The marmoset showed antibodies against EBV capsid and early antigens (VCA, EA) but not against nuclear antigen (EBNA). EBNA was detected in impression smears from lymph nodes and liver, and the presence of the EBV genome was detected from the same organs by hydridization techniques. To our knowledge this is the first report of the oncogenicity of this strain of EBV. The need for further studies to assess the in vivo interaction between EBV and tumor promoting agents in the development of malignancies is stressed.     

Lymphoma in Miniature Dachshunds: A retrospective multicenter study of 108 cases (2006‐2018) in Japan

BackgroundMiniature Dachshunds (MD) are predisposed to lymphoma with disease onset of young age and long‐term survival.ObjectivesTo compare clinical features and survival time of lymphoma in MD and non‐MD.AnimalsOne hundred and eight MDs with lymphoma and 149 non‐MD breed dogs with lymphoma were included in the study.MethodsThis was a retrospective multicenter observational study. Lymphoma was classified based on signalment, histopathology/cytology, and anatomical site of the disease. For each type of lymphoma, median survival time was analyzed by Kaplan‐Meier estimates and life table analysis. Prognostic factors for large‐cell gastrointestinal lymphoma (LGIL) were analyzed using Cox regression.ResultsGastrointestinal lymphomas were more common in MDs (53/108) compared to non‐MDs (41/149). The multicentric lymphoma was most common in non‐MD breed dogs (74/149) compared to MDs (33/108). The median age that dog developed lymphoma in MD and non‐MD were both 10 years old; however, lymphomas were more frequently observed in younger dogs (<4 years) in MDs (20/108) compared to non‐MDs (9/149; P = .002). Seventy percent were diagnosed with B‐cell with median age of diagnosis was 3 (1‐14) years. Mott cell differentiation was observed in 6 dogs. Age <4 years and B‐cell phenotype were significant factors for longer survival time in MD with LGIL.Conclusions and Clinical ImportanceLymphomas in MDs involved gastrointestinal lesions at higher frequency compared to other dog breeds examined. B‐cell lymphoma was more common in early‐onset LGIL in MD and cases that involved Mott cell differentiation were observed. Awareness of this specific presentation of lymphoma in dogs will possibly affect the treatment decision process for the owners of MD with LGIL.     

A Retrospective Study of Multi‐agent Chemotherapy including either Cyclophosphamide or Lomustine as Initial Therapy for Canine High‐grade T‐cell Lymphoma (2011‐2017)

Multi‐agent chemotherapy (vincristine, epirubicin and prednisolone) including either cyclophosphamide (CEOP) or lomustine (LEOP) was given as first‐line chemotherapy to treatment‐naïve canine lymphoma patients with measurable, high grade T‐cell lymphoma (HGTCL). All patients responded to either CEOP or LEOP. Toxicity was typical of multi‐agent chemotherapy protocols and 25% of dogs receiving lomustine exhibited mild‐to‐moderate ALT elevation and 29% grade 3 or 4 neutropenia. Median progression‐free survival (100 versus 269 days) and overall survival (155 versus 327 days) were significantly higher in patients receiving LEOP compared to CEOP. Overall survival was improved for patients receiving LEOP compared to those receiving CEOP followed by lomustine‐based rescue therapy. The results of this retrospective study support further evaluation of lomustine as part of first‐line, multi‐agent therapy for patients with HGTCL.     

More effective induction of anesthesia using midazolam-butorphanol-ketamine-sevoflurane compared with ketamine-sevoflurane in the common marmoset monkey (Callithrix jacchus)

The common marmoset has been increasingly used for research in the biomedical field; however, there is littleinformation available regarding effective methods of anesthesia in this species. This study retrospectivelyanalyzed 2 regimens of anesthesia induction: intramuscular injection of ketamine followed by inhalation of 5%sevoflurane, and intramuscular injection of midazolam, butorphanol and ketamine followed by inhalation of 5%sevoflurane. Anesthetic depth did not reach the surgical anesthesia stage in 7 out of 99 animals receiving theformer regimen, whereas there were only 2 such animals out of 273 receiving the latter regimen. The latterregimen, when followed by maintenance anesthesia with 3% sevoflurane inhalation, was successfully used invarious nociceptive procedures. These results indicate that the injection of a combination of midazolam,butorphanol and ketamine followed by inhalation of a high concentration of sevoflurane is effective foranesthesia induction in marmosets.     

A Case of Spontaneous Malignant Hibernoma in a Crl:CD(SD)IGS Rat

A firm, tan, well-circumscribed mass that measured 25 × 30 × 35 mm was observed in the thoracic cavity of a 53-week-old male Crl:CD(SD) IGS rat. Histologically, the mass was encapsulated by fibrous tissue and contained fibrovascular septae. Tumor cells were compactly arranged, and most were oval to polygonal in shape with multivacuolated cytoplasm and a centrally located nucleus. In some parts of the tumor, marked cellular atypia and frequent mitoses were evident. Vacuoles in cytoplasm were positive for oil red O. The tumor cells were characterized ultrastructurally by abundant, round to oval mitochondria with transverse closely-packed cristae. Tumor cells were immunohistochemically positive for uncoupling protein 1 (UCP-1). Several thrombi and hemorrhagic or necrotic foci were also observed within the tumor mass. Vascular invasion of the tumor capsule was observed; however, invasion of surrounding tissues or metastases were not observed. Based on the pathology findings, this case was diagnosed as a malignant hibernoma.     

Epidermotropic Cutaneous T-Cell Lymphoma (mycosis fungoides) in Syrian Hamsters (Mesocricetus auratus). A Report of Six Cases and the Demonstration of T-Cell Specificity

Abstract— Epidermotropic cutaneous T-cell lymphoma was diagnosed in six Syrian hamsters (Mesocricetus auratus) with a generalised dermatosis characterised by pruritus, alopecia and exfoliative erythroderma. Plaques and nodules were evident in one animal. Clinical and histopathological findings were suggestive of mycosis fungoides and electron microscopical investigations in one case were supportive. Immuno-histochemical stains for CD3 antigen were strongly positive in all cases. Résumé— Un lyphome T cutané a été diagnostiqué chez six hamsters de Sibérie (Mesocricetus auratus) avec une dermatose généralisée, caractérisée par un prurit, une alopécle et une érythrodermie exfoliative. Des plaques et des nodules ont été observées sur un animal. Les données cliniques et histopathologiques étaient évocatrices d'un mycosis fungoïdes et les examens en microscopie électronique étaient compatibles dans un cas. Les marquages immuno-histochimiques de l'antigène CD3 étaient très positifs dans tous les cas. Zusammenfassung— Bei sechs Syrischen Goldhamstern (Mesocricetus auratus) wurde ein epidermotropes kutanes T-Zell-Lymphom mit einer generalisierten Dermatose diagnostiziert, die durch Pruritus, Alopezie und eine exfoliative Erythrodermie gekennzeichnet war. Bei einem Tier traten auch Plagues und Knoten auf. Die klinischen und histopathologischen Befunde deuteten auf Mycosis fungoides hin. Elektronenmikroskopische Untersuchungen unterstützten diesen Verdacht in einem Fall. Immunhistochemische Färbungen auf CD3-Antigen waren bei alien Fallen stark positiv. Resumen En un grupo de seis hamsters de siria, (Mesocricetus auratus), se diagnosticó limfoma epidermotrópico cutáneo de linfocitos T, presentando una dermatosis generalizada de tipo pruriginoso, acompañada de alopecia y eritroderma exfoliativo. Las placas y nódulos fueron evidentes en uno de los animales. Los estudios clinicos e histopatológicos indicaron una micosis fungoide, y las investigaciones de microscopía, en uno de los caseos, pareció indicar lo mismo. La tintura inmuno-histoquimica para el antígeno CD3 resultó claramente positiva en todod los casos.     

Nonregenerative immune‐mediated anemia associated with a diffuse large B‐cell lymphoma in a captive jaguar (Panthera onca)

An 18‐year‐old male castrated jaguar (Panthera onca) was presented with anorexia and continuous bleeding from the oral cavity after a history of fighting with the partner animal. Clinical evaluation revealed ulcerating lesions on the gingiva and hard palate and a hematoma on the tongue. Computed tomography of the head and endoscopic examination of the esophagus and stomach were unremarkable. Hematology and clinical chemistry revealed severe nonregenerative anemia, mild thrombocytopenia, and moderate azotemia. Several PCRs for feline hemotropic mycoplasmas (Mycoplasma haemofelis, M heamominutium, M turicensis), Babesia felis, and Bartonella spp., as well as an FeLV antigen test were negative. The cytologic examination of a bone marrow aspirate was consistent with ineffective erythropoiesis, most likely due to immune‐mediated destruction of the erythroid precursor cells. Prednisolone therapy was initiated (1.25 mg/kg/day), and the CBC returned to normal 16 days after the initiation of the therapy. Anemia relapsed after 4 months and severe splenomegaly was noted. A repeat bone marrow aspirate revealed active erythropoiesis in the presence of erythroid precursor phagocytosis suggesting an immune‐mediated process. Splenic fine‐needle aspiration and tissue biopsies were taken, and all findings including histology and immunohistochemistry were consistent with a diffuse large B‐cell lymphoma (DLBCL). Five days later, the clinical condition deteriorated and the jaguar died. Histopathology following necropsy showed infiltration with neoplastic lymphoblasts in the spleen, liver, and abdominal lymph nodes. This case report describes a nonregenerative immune‐mediated anemia associated with a DLBCL in a jaguar.     

Spontaneous Extraskeletal Osteosarcoma in a Rabbit (Oryctolagus cuniculus): Histopathological and Immunohistochemical Findings

A spontaneously occurring subcutaneous mass in the left forelimb of a nine-year-old rabbit (Oryctolagus cuniculus) was examined histopathologically and immunohistochemically. Clinically, edema and hemorrhage were seen around the mass. No connection of the tumor mass to the appendicular skeleton was found. The tumor was arranged in a solid growth pattern and irregular bundles, and neoplastic cells were polygonal to spindle-shape. Osteoid (positive for osteocalcin) and multinucleated giant cells were diffusely or focally seen. Neoplastic cells were positive for vimentin, osterix and Ki-67, indicating the nature of osteoblasts with proliferating activity, but negative for α-smooth muscle actin, desmin or CD204. Based on these findings, a diagnosis of extraskeletal osteosarcoma was made, a very rare tumor both in laboratory and pet rabbits.