Pathological features of hepatic portal venous gas in a cat

An 8-year 8-month-old castrated male Munchkin presented with vomiting, anorexia and hypoactivity. Computed tomography revealed excessive gas accumulation within the intestinal lumen and gas bubbles in the liver, spleen, and portal venous system, indicating hepatic portal venous gas. The cat died without any significant improvement, and mild splenomegaly was found at necropsy. Histologically, multiple gas vacuoles were diffusely observed in the liver and spleen. In the stomach, multiple gas vacuoles and scattered focal ulcers were detected within the mucosa. Multifocal hemorrhage was noted in the small and large intestines, whereas gas vacuoles were not present. Based on these findings, a gastric ulcer under high gas pressure may have provided an entry point for gas into the portal venous system.     

Lymphangiosarcoma with systemic metastases in a Japanese domestic cat

A 4-year-2-month-old female Japanese domestic cat was diagnosed with lymphangiosarcoma through tissue biopsy of an amputated leg. Two months later, the cat was euthanized, and postmortem findings revealed edema, and bruising at the caudal region of the trunk, pulmonary hemorrhage, pulmonary nodules and mediastinal lymphadenopathy. Microscopically, neoplastic tissues were observed in the dermis and subcutis of the trunk, lung, mediastinal lymph nodes, diaphragm, omentum and mesentery. The tumor cells were spindle to polygonal-shaped with nuclear pleomorphism aligning along pre-existing collagen bundles and forming irregular vascular channels in which the erythrocytes were rarely observed. These cells were immunopositive for vimentin, von Willebrand factor and CD31. Based on the histopathological and immunohistochemical features, the neoplasia was diagnosed as lymphangiosarcoma with systemic metastases.     

Detection of indoleamine 2,3-dioxygenase 1-expressing cells in canine normal and tumor tissues

Cancer immunotherapy is a novel cancer treatment for canine tumors. Indoleamine 2,3-dioxygenase 1 (IDO1) is overexpressed in some human tumors and inhibits antitumor immunity. In this study, we comprehensively evaluated expression pattern of IDO1 and the nature of IDO1-expressing cells in canine normal and tumor tissues. In normal tissue samples, IDO1 expression was detected only in the lymph nodes, spleen, tonsil tissues, and colon tissues. In contrast, IDO1-positive tumor cells were observed in several tumor tissue types. This is the first study to evaluate IDO1 expression in canine normal and tumor tissues, and the results suggest that IDO1 is a promising target for novel cancer immunotherapy in dogs with tumors.     

Rapid visualization of mammary gland tumor lesions of dogs using the enzyme-activated fluorogenic probe; γ-glutamyl hydroxymethyl rhodamine green

Since gamma-glutamyl transpeptidase (GGT) is highly and locally expressed in human breast cancer, a GGT-enzymatically activatable fluorescent probe, gamma-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG), has been developed to detect the human breast cancer area with high performance. In this study, GGT expression and the efficacy of gGlu-HMRG on visualization were investigated in canine mammary gland tumors (MGT). Seventeen non-fixed fresh-frozen MGT specimens and each peritumoral control tissue were utilized. The GGT mRNA levels were highly observed in the tumor specimens compared with the control. GGT immunostaining was mostly observed on the cell membrane and cytosol of the alveolar and duct mammary epithelium of MGT tissues. These signals were strongly positive in several cases while they were mild to not observed in other cases. When gGlu-HMRG solution was dropped to the non-fixed tissue pieces of MGT or control tissues, the fluorescence intensities (FIs) were measured using Maestro in-vivo imaging device. FIs in MGT tissues were significantly higher than each control tissue 20 min after treatment. Based on Youden index method said that the maximum sensitivity and specificity of FI was 82.4% and 82.4%. These findings suggest that GGT is highly expressed in several MGTs in dogs and gGlu-HMRG could visualize at least a part of MGT tissues in dogs. Nevertheless, it should be needed to assess the false-negative areas more carefully in canine than human cases.     

Immunohistochemical study of autophagy associated molecules and cell adhesion molecules in canine intracranial granular cell tumors

Granular cell tumors (GCTs) are characterized by abundant eosinophilic cytoplasmic granules. Based on the hypothesis that canine intracranial GCT is a subtype of meningioma and its cytoplasmic granules are formed through autophagy processes, histopathological and immunohistochemical examination were performed on biopsy samples from 7 cases of canine intracranial GCTs and 15 cases of conventional meningiomas. Histopathologically, 7/7 cases of GCTs involved the meninges; foci of meningothelial-like cells were observed in 3/7 cases; brain invasion was observed in 2/7 cases. Immunohistochemically, neoplastic cells of GCTs were positive for E-cadherin and negative for S100, cytokeratin, CD204, and β-catenin in 7/7 cases. Neoplastic cells of 15/15 cases of meningiomas were positive for E-cadherin, and negative for S100 and CD204. Immunoreactivity of meningiomas for cytokeratin and β-catenin was observed in 6/15 cases and 8/15 cases, respectively. Cytoplasmic granules of GCTs were positive for ubiquitin (5/7), p62 (5/7), and LC3 (7/7). Compared to GCTs, the ratios of ubiquitin (6/15) and p62 (3/15) positive cases were lower in meningiomas, and 15/15 cases were negative for LC3. These findings indicate that the biological natures of GCTs including anatomical location, histopathological features and immunoreactivity for E-cadherin are almost in conformity with those of meningiomas. The immunoreactivity for autophagy associated molecules may suggest the possible involvement of autophagy in cytoplasmic granule formation of canine intracranial GCTs.     

Systemic Streptococcus agalactiae infection with meningo-ventriculitis in a Linnaeus’s two-toed sloth (Choloepus didactylus)

A captive male Linnaeus’s two-toed sloth died without any obvious clinical signs. At necropsy, multifocal ulceration at the lumbar and perianal skin, mitral valve vegetation, and multifocal hemorrhage in the leptomeninges were observed. Histopathologically, suppurative meningo-ventriculitis, dermatitis, and endocarditis characterized by severe neutrophilic infiltration were observed. Gram-positive cocci arranged in pairs or chains were present in these inflammatory lesions. Streptococcus agalactiae gene was detected in the skin, heart, and brain tissues by PCR and sequence analysis. These findings may indicate that S. agalactiae primarily infected the skin and then caused septicemia resulting in endocarditis and meningo-ventriculitis. The present case suggests that S. agalactiae infection can cause severe meningo-ventriculitis in two-toed sloth without any specific clinical signs.     

Choroid plexus papilloma in a dog surviving for 15 months after diagnosis with symptomatic therapy

A 4-year-old female French bulldog presented with a 6-month history ofright-sided head tilt and acute onset ataxia. Magnetic resonance imaging (MRI) showed alarge mass lesion at the cerebellomedullary pontine angle. The dog was able to stand andwalk after beginning symptomatic therapy with prednisolone, acetazolamide and glycerin.Magnetic resonance imaging 10 months after the first examination indicated slightexpansion of the tumor. The dog was able to walk with continuous symptomatic therapy for15 months until death, although the head tilt persisted. On postmortem examination, thegross tumor was slightly larger than when seen on the second MRI scan and washistopathologically diagnosed as a choroid plexus papilloma.