Identification of apolipoprotein E-derived amyloid within cholesterol granulomas of leopard geckos (Eublepharis macularius).

Apolipoprotein E (ApoE) is involved in cholesterol transport among cells and also plays an important role in amyloid formation, co-depositing with amyloid fibrils in various types of amyloidosis. Although the in vivo amyloidogenicity of ApoE has not been previously demonstrated, this study provides evidence of ApoE amyloidogenicity in leopard geckos (Eublepharis macularius), belonging to the class Reptilia. Histologically, amyloid deposits were localized within cholesterol granulomas and exhibited positive Congo red staining, with yellow to green birefringence under polarized light. On mass spectrometry-based proteomic analysis, ApoE was detected as a dominant component of amyloid; of the full length of the 274 amino acid residues, peptides derived from Leu185-Arg230 were frequently detected with non-tryptic truncations. Immunohistochemistry with anti-leopard gecko ApoE antibody showed positive reactions of amyloid deposits. These results show that ApoE is an amyloid precursor protein within the cholesterol granulomas of leopard geckos. Although further investigations are needed, the C-terminal region of ApoE involved in amyloid formation is a lipid-binding region, and there should be a relationship between amyloidogenesis and the development of cholesterol granulomas in leopard geckos. This study provides novel insights into the pathogenesis of ApoE-related diseases.

Establishment of a histiocytic sarcoma cell line and anti-tumor effect of bortezomib in the African pygmy hedgehog (Atelerix albiventris).

The African pygmy hedgehog (Atelerix albiventris) is known to have a high incidence of tumor. However, investigating the tumors of this species has been constrained by the limited availability of research materials such as cell lines and genome information. In this study, we successfully established a novel cell line from a histiocytic sarcoma (HS) of an African pygmy hedgehog, allowing us to conduct a drug screening. We investigated using FDA-approved drug library screening to determine which anticancer drug this tumor cell line is sensitive to, and as a result of apoptosis experiments, bortezomib among the three proteasome inhibitors was found to induce cell death of cancer cells by significantly increasing caspase-3 cleavage (P<0.01). Thus, we elucidated that the proteasome inhibitors, particularly bortezomib, exhibit anti-tumor effects on a cell line derived from an HS in an African pygmy hedgehog through a mechanism comparable to that described in human tumors. This study reports the first characterized cell line from the African pygmy hedgehog and also highlights the potential utility of bortezomib as an anti-tumor treatment for HS in this species.

The first report of ovarian torsion causing intracoelomic hemorrhage and subsequent hemorrhagic shock in a captive Humboldt penguin (Spheniscus humboldti).

A 21-year-old captive female Humboldt penguin (Spheniscus humboldti) was in good health until the day before the animal died. However, the animal suddenly exhibited symptoms of vomiting and anorexia, and died in shortly thereafter. The autopsy revealed a blood clot in the abdominal air sac and 280 mL of dark red fluid in the body cavity. The ovary was twisted around a blood vessel. Based on the findings described, it was considered that the cause of death was hypovolemic shock due to massive intracoelomic hemorrhage by vascular collapse resulting from ovarian torsion. This is the first report of ovarian torsion in penguins.

Disseminated histiocytic sarcoma in a degu (Octodon degus).

A 7-year-and-8-month-old, male degu (Octodon degus) with anorexia, depression, and labored breathing was found to have a thoracic effusion and enlargement of the right testis on radiographic examination. Despite treatment, the animal died. At necropsy, hepatomegaly, splenomegaly, and multifocal nodules on the intestinal serosa and mesentery were observed. Histologically, the foci were densely cellular invasive neoplasms composed of sheets of round to polygonal cells, with occasional multinucleated giant cells. Immunohistochemically, the neoplastic cells were immunopositive for ionized calcium-binding adapter molecule 1, human leukocyte antigen-DR, and CD204. These findings were consistent with disseminated histiocytic sarcoma.

Bilateral renal dysplasia with systemic fibrous osteodystrophy in a four-toed hedgehog (Atelerixalbiventris).

A 4-month-old female four-toed hedgehog (Atelerix albiventris) presented with lethargy, anorexia, dyspnoea and weight loss. Following death, post-mortem computed tomography (CT) and an autopsy were performed. CT revealed that the external surfaces of bones, including the cranial bones and vertebrae, were rough and osteolytic lesions were present multifocally in the ribs and some appendicular bones. On gross examination, both kidneys were severely enlarged and, on cut sections, a few cysts (up to 1 mm diameter) were present in the medulla. The cervical, thoracic and lumbar vertebrae were diffusely enlarged with deformation of the intervertebral discs. Histologically, there were immature glomeruli and tubules and adenomatoid/atypical epithelium in the kidneys. These changes were interpreted as renal dysplasia. In the bones evaluated, the trabeculae were thinner than normal, decreased in number and surrounded by many osteoclasts, with abundant fibrous connective tissue between atrophied trabeculae. These changes were consistent with fibrous osteodystrophy. Although kidney diseases are common in four-toed hedgehogs, there are no reports of congenital renal diseases, including renal dysplasia. To the best of our knowledge, this is the first report of the clinical and pathological features of renal dysplasia with fibrous osteodystrophy in a four-toed hedgehog.

Pyometra in a sugar glider (Petaurus breviceps): surgical treatment and postoperative complications.

A 7-year-old female sugar glider showed a well-defined, homogeneous, hypoechoic mass in the caudal abdominal cavity on ultrasound. Exploratory laparotomy revealed both uteri were severely dilated by viscous, purulent exudate. The patient underwent ovariohysterectomy with removal of bilateral vaginal canals. Antibiotic therapy was initiated postoperatively. Histopathological findings were consistent with suppurative metritis, leading to a clinical diagnosis of pyometra. Despite abscess formation in the uterine stump or central vaginal canal and bilateral renal pelvic/ureter dilations postoperatively, the sugar glider survived more than 270 days. Unfortunately, surgical and medical treatments performed in this case did not prove curative. The outcome of this case highlights the importance of further accumulation of cases to define more appropriate therapies for pyometra in sugar gliders.

B-Cell Lymphoma of the Middle Ear Treated with Multidrug Chemotherapy in a Cat.

Primary lymphoma of the middle ear is rare in cats, and little information has been accumulated on the treatment and course. An 11-year-old spayed female mixed-breed cat was brought to our hospital with facial nerve paralysis, which had been stable using prednisolone for 3 months. She was diagnosed with B-cell lymphoma of the right middle ear after otoscopic sampling, which showed evidence of the filling of bilateral tympanic bullae on computed tomography. Hepatic involvement was suspected, and she was treated with multidrug chemotherapy, resulting in clinical remission. On day 176, magnetic resonance imaging and computed tomography were performed at checkup, revealing tumor invasion into the nasopharyngeal region and the recurrence of hepatic lesions without any brain abnormality. Nasal congestion then worsened, and the patient died on day 228 after presenting with generalized seizures. Clinicians should be mindful of middle ear lymphoma as a differential diagnosis in cats who present with a sign of otitis media, especially whose condition does respond to corticosteroid treatment. The prognosis for feline middle ear lymphoma might not be as poor as previous reports, and multidrug chemotherapy might result in remission of the disease.

Toceranib phosphate and firocoxib-mediated partial response in a dog with advanced intranasal sarcoma.

A nine-year-old, castrated male mixed-breed dog presented with a three-month history of sneezing and stertorous breathing. Computed tomography revealed a soft tissue mass in the left nasal cavity with lysis of the cribriform plate. The mass was diagnosed as intranasal sarcoma based on histopathological analysis. The tumor cells were immunohistochemically positive for KIT and platelet-derived growth factor receptor α/ß and negative for vascular endothelial growth factor receptor 2 and cyclooxygenase-2. Treatment with toceranib phosphate (TOC) and firocoxib reduced the tumor size, which was defined as partial response (PR). After PR induction, TOC alone mediated survival for 205 days. This case report suggests that the combination of TOC and possibly firocoxib may be a therapeutic option for canine intranasal sarcoma.

Aortic valve insufficiency caused by a hypoplastic aortic valve in a calf.

A 1-month-old crossbred calf was referred for examination due to marked systolic heart murmurs and poor growth. The heart murmur was most audible on the right side of the cranial thorax. Cardiomegaly was evident on chest radiography, and echocardiography demonstrated aortic regurgitation and decreased fractional shortening. Cardiomegaly, aortic root dilation and cardiac displacement were confirmed by computed tomography. At necropsy, the heart was enlarged, and all three aortic valve leaflets were irregularly shaped. In calves with chronic aortic insufficiency, remodeling displacement of the heart and aorta causes changes in the location and timing of heart murmurs. Therefore, aortic insufficiency cannot be ruled out when a systolic heart murmur can be observed in the right chest wall.

Anaplastic oligodendroglioma with nasal invasion and systemic metastasis in a dog.

An 11-year-old spayed female French bulldog was referred on suspicion of nasal tumor. Anaplastic oligodendroglioma in the olfactory bulb that was suspected to have invaded the nasal cavity was diagnosed from imaging and histopathology. Metastasis to cervical lymph nodes was suspected, with no other metastases identified. The brain-to-nasal lesion and lymph nodes were treated with hypo-fractionated radiation therapy. Nasal congestion soon resolved. About 3 months later, follow-up computed tomography revealed multiple hepatic and splenic masses, which were cytologically suspected as metastatic oligodendroglioma. Nimustine, followed by toceranib phosphate, seemed to have no effect, and the dog died on day 167. Postmortem examination revealed the primary tumor disappearance and systemic metastases. Canine oligodendroglioma can grow outside the cranial vault, and systemically metastasize.

Fibrinogen Aα-chain amyloidosis outbreaks in Japanese squirrels (Sciurus lis): a potential disease model.

Fibrinogen Aα-chain amyloidosis is a hereditary systemic amyloidosis characterized by glomerular amyloid depositions, which are derived from the fibrinogen Aα-chain variant in humans. Despite its unique pathology, the pathogenic mechanisms of this disease are only partially understood. This is in part because comparative pathological studies on fibrinogen Aα-chain amyloidosis are currently unavailable as there is a lack of reported cases in animals other than humans. In this study, mass spectrometry-based proteomic analyses of Japanese squirrels (Sciurus lis) that died in five Japanese zoos showed that they developed glomerular-associated fibrinogen Aα-chain amyloidosis with an extremely high incidence rate (29/38 cases, 76.3%). The condition was found to be age-dependent in the Japanese squirrels, with 89% of individuals over 4 years of age affected. Mass spectrometry revealed that the C-terminal region of the fibrinogen Aα-chain was involved in amyloidogenesis in Japanese squirrels as well as humans. No gene variations were identified between amyloid-positive and amyloid-negative squirrels, which contrasted with the available data for humans. The results indicate that fibrinogen Aα-chain amyloidosis is a senile amyloidosis in Japanese squirrels. The results have also provided comparative pathological support that the amyloidogenic C-terminal region of the fibrinogen Aα-chain is involved in the characteristic glomerular pathology, regardless of the animal species. This study elucidates the potential causes of death in Japanese squirrels and will contribute to future comparative pathological studies of fibrinogen Aα-chain amyloidosis. © 2023 The Pathological Society of Great Britain and Ireland.

Identification and characterization of the genome of a papillomavirus from skin lesions of four-toed hedgehogs (Atelerix albiventris).

The present study describes the clinical and pathological characteristics of skin lesions in two four-toed hedgehogs (Atelerix albiventris). We performed inverse PCR to identify the genome of papillomavirus (PV) in the skin lesions and subsequently sequenced the full genome of the virus, which was tentatively named Atelerix albiventris papillomavirus 1 (AalbPV1). The overall sequences of the viral genomes of both four-toed hedgehogs were identical. This study first identified the presence of a novel PV in Japanese four-toed hedgehogs and provided genetic information about this virus.

First case of hemochromatosis in a sugar glider (Petaurus breviceps).

A 14-year-old, male sugar glider presented with lethargy, anorexia, diarrhea, and paralysis of the hind limbs, and ultrasonography showed possible liver dysfunction. Some medications were administered, but the animal died 10 months after the first presentation, and a necropsy was performed. Histopathologically, hepatocellular degeneration and necrosis, severe deposition of hemosiderin in Kupffer cells and hepatocytes, bridging fibrosis, and regenerative nodules were observed in the liver. Variably amounts of hemosiderin deposition was observed in the heart, lungs, spleen, and kidney. These findings led to the diagnosis of hemochromatosis. No sugar glider cases with hemochromatosis have been reported. The pathological characteristics of hemochromatosis in this species were documented for the first time. The pathogenesis of hemochromatosis in animals remains unclear, but it has been suggested that some commercially available food for sugar gliders containing excessive amounts of iron and vitamin C may induce the disease.

Morphological study of apocrine gland tumors in domestic Richardson's ground squirrels (Urocitellus richardsonii).

The morphology of 58 apocrine tumors from 31 domestic Richardson's ground squirrels (Urocitellus richardsonii) was examined, comparing tumor subtypes with clinical information and histological findings. The squirrels included 23 males (74%) and 8 females (26%). Of the 58 tumors, 36 (62%) were located from the cervical skin to the dorsal skin, 17 (29%) were from the perioral region to the cheek, and the location was unrecorded for the remaining 5 squirrels (9%). Histologically, 49 tumors (84%) were apocrine adenocarcinomas, 6 were apocrine adenomas (10%), and 3 were apocrine cysts (5%). The 49 apocrine adenocarcinomas were subclassified as 16 (33%) cystic papillary type, 16 (33%) tubulopapillary type, 12 (24%) solid type, and 5 (10%) micropapillary invasive type. Fisher's exact test revealed correlations between tumor subtypes and tumor diameters, nuclear atypia, tumor margins, vascular invasion, and periodic acid-Schiff (PAS) positivity. This study showed a predominance of apocrine adenocarcinomas with various histological subtypes. In addition, subclassification of these tumors was useful for predicting the biological behavior of apocrine gland tumors in Richardson's ground squirrels.

Expression of genes encoding interleukin 15 and its receptor subunits in the duodenal and colonic mucosae of dogs with chronic enteropathy.

A pro-inflammatory role of interleukin (IL)-15 and IL-15 receptor (R) in chronic intestinal inflammation, such as inflammatory bowel disease, has been reported in humans. However, the contribution of IL-15 signaling in the pathogenesis of canine chronic enteropathy (CE) remains unclear. Therefore, as a first step in elucidating the importance of IL-15 signaling in canine CE, we measured the mRNA expression of IL-15 and IL-15R subunits, including IL-15Rα, IL-15Rß, and IL-15Rγ, in the duodenal and colonic mucosae of healthy dogs and those with CE, including food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), and immunosuppressant-responsive enteropathy (IRE). Real-time PCR analysis revealed significantly lower IL-15Rα mRNA expression levels in the duodenal mucosa of dogs with IRE compared to healthy dogs. In contrast, the mRNA expression levels of IL-15, IL-15Rß, and IL-15Rγ in the duodenal mucosa and IL-15, IL-15Rα, IL-15Rß, and IL-15Rγ in the colonic mucosa did not differ among healthy dogs and those with FRE, ARE, or IRE. These findings suggest that decreased mRNA expression of IL-15Rα might be involved in the pathogenesis of duodenitis in dogs with IRE. Moreover, even in canine CE, IL-15 signaling appears to play different roles in duodenitis and colitis in dogs with FRE, ARE, and IRE. However, there were no correlations between the gene expression levels of IL-15Rα and clinical severity or histopathological scores in the duodenum of dogs with IRE. Further studies are necessary to investigate the IL-15Rα protein localization and to determine how impaired IL-15Rα expression contributes to the development of duodenitis in dogs with IRE.

Clinical course and pathologic study of retrobulbar histiocytic sarcoma in a central bearded dragon (Pogona vitticeps).

A central bearded dragon (Pogona vitticeps) presented with periorbital swelling and exophthalmos. A retrobulbar mass was detected, and enucleation with the mass was performed. Histologically, the mass was composed of a dense sheet and interlacing bundles of round to polygonal to short spindle-shaped cells with occasional bizarre mononuclear and multinucleated giant cells. Immunohistochemically, the neoplastic cells had various degrees of membranous and/or cytoplasmic granular reactivity to anti-ionized calcium-binding adapter molecule 1 and anti-CD204 antibodies. Ultrastructurally, the neoplastic cells had irregular nuclei and abundant cytoplasm with membrane-bound electron-dense lysosomes and endoplasmic reticula. These findings were consistent with a histiocytic sarcoma. The present study provided a detailed description of retrobulbar histiocytic sarcoma for the first time in a central bearded dragon.

Clinical characteristics of dogs presenting with vomiting as a gastrointestinal sign of chronic enteropathy.

Vomiting is a major gastrointestinal (GI) sign of chronic enteropathy (CE) in dogs. Previous studies have reported clinical characteristics of dogs with CE, who developed diarrhea with or without vomiting as GI signs. However, to characterize clinical features of dogs with CE appropriately, dogs presenting with vomiting without diarrhea should be included in the analysis. Thus, this study aimed to characterize clinical features and outcomes of dogs that presented with vomiting without diarrhea. Based on their presenting GI signs, we retrospectively classified 66 dogs with CE into "Vomiting", "Diarrhea", or "Vomiting and diarrhea" groups and compared clinical and histological characteristics of each group. We found that 18 of the 66 dogs with CE (27%) presented with vomiting without diarrhea as a GI sign. Compared to the other 2 groups, the Vomiting group was significantly associated with food-responsive enteropathy (FRE), Beagle, lower clinical severity scores, higher plasma albumin levels, and higher histological scores for eosinophils in the duodenal lamina propria according to the univariate analysis. The multivariate analysis revealed that FRE and higher histological scores for eosinophils in the duodenal lamina propria were significant variables in the Vomiting group. Moreover, the survival time was the longest in the Vomiting group among dogs with CE. These findings are of clinical significance as they indicate that presenting with vomiting without diarrhea may not only be helpful in differentiating FRE from the other types of CE, but also in predicting the prognosis.

Thymoma originating from the cervical component of the thymus in a degu.

A 5-y-old, male degu (Octodon degus) was presented with a subcutaneous mass in the ventral aspect of the cervical area. The mass was removed surgically. Histologically, the mass was a densely cellular, expansile neoplasm, with compression of thymic tissue to the periphery. The neoplasm consisted of solid sheets of polygonal cells, mixed with fewer small lymphocytes. Rare Hassall bodies were scattered throughout the mass. Polygonal cells were positive for anti-keratin/cytokeratin AE1/AE3 antibody, and small lymphocytes were positive for anti-CD3 antibody. The histopathologic and immunohistochemical findings were consistent with a thymoma. In addition, an autopsy revealed myxosarcoma of the right thoracic wall with metastasis to the lung. To our knowledge, thymoma originating from the cervical component of the thymus has not been documented previously in a rodent species.

Cutaneous papilloma and multicentric squamous cell carcinoma in four-toed hedgehogs (Atelerix albiventris).

Skin lesions possibly caused by Papillomavirus infections in two four-toed hedgehogs are described. In case 1, there was a papillary mass on the right hind limb. Histologically, the mass was consistent with a viral papilloma. In the other case, multifocal papillary masses with erosions and ulcers were found throughout the body, mainly on the extremities. Histology showed continuative lesions composed of acanthosis, Bowenoid in situ carcinoma, and squamous cell carcinoma, with abrupt transitions between the lesions. In both cases, keratinocytes in the granular layer infrequently had features of koilocytes and intranuclear inclusion bodies, and immunohistochemical staining was positive for anti-human papillomavirus antibody. To the best of the authors' knowledge, this is the first pathological documentation of possibly papillomavirus-associated skin lesions in four-toed hedgehogs.

Long-term management of a cat with nasopharyngeal lymphoma by chlorambucil.

Background: Lymphoma in the nasal cavity is the most common tumor of cats' upper respiratory tract. However, the effect of single-agent chlorambucil on nasal or nasopharyngeal lymphoma has not been evaluated in cats. Case Description: An 8-year-old, castrated male Scottish Fold weighing 3.5 kg presented with an 8-month history of nasal discharge, sneezing, and mild epistaxis. CT and rhinoscopy revealed nasal discharge and slight swelling of the nasopharyngeal mucosa, but no masses and local invasions were detected. Histopathological and immunohistochemical analyses of the nasopharyngeal mucosa demonstrated B-cell lymphoma in the cat. The treatment with chlorambucil led to long-term management of the cat without any side effects. No recurrences of clinical signs have been observed for 754 days. Conclusion: The present case report suggests that chlorambucil can be a therapeutic option for feline localized nasopharyngeal B-cell lymphoma without masses and local invasions.