Detailed clinicopathological and ultrastructural characterizations of bovine renal thrombotic microangiopathy (TMA) remain limited. A 20-month-old castrated Japanese Black (Bos primigenius taurus) steer was presented with depression and severe azotaemia. Histologically, glomeruli varied considerably in size, with many being reduced in size and collapsed or with global sclerosis, whereas enlarged glomeruli were less frequent. Intraglomerular thrombi consisted predominantly of periodic acid-Schiff-positive hyaline material, while fibrin-positive thrombi were infrequent. Small arteries and arterioles had concentric wall thickening with marked narrowing of the lumina, and similar vascular lesions were observed in the jejunal submucosa also. Ultrastructurally, glomerular capillaries showed severe narrowing of the lumina, accompanied by frequent mesangial interposition and multilayering of the glomerular basement membrane. No electron-dense immune deposits were identified. These findings were consistent with subacute-to-chronic endothelial injury-associated TMA with membranoproliferative remodelling. This case provides a comprehensive clinicopathological and ultrastructural characterization of bovine renal TMA.
Amebiasis is a parasitic disease primarily associated with amoeboid protozoa of the genus Entamoeba; however, comparable infections may also be caused by other genera in different hosts. In reptiles, it is mainly attributed to Entamoeba invadens, which can be fatal in several species. This report describes an outbreak of amebiasis in two species of testudines, red-footed tortoises (Chelonoidis carbonarius) and black-bellied sliders (Trachemys dorbigni), from a wildlife screening and rehabilitation centre in Minas Gerais, Brazil. The facility housed around 130 testudines, and between 2022 and 2024, 79 animals died, of which 21 were diagnosed with amebiasis based on post-mortem examination. Clinical signs were non-specific, including anorexia, lethargy, reluctance to move and sudden death. Histological lesions were most frequent in the liver (17/21), duodenum (10/21) and colon (4/21), but were also present in the coelomic wall (4/21), lungs (2/21) and spleen (1/21). Lesions were characterized by necrosis, fibrin deposition and inflammatory infiltrates of lymphocytes and histiocytes, associated with numerous intralesional amoeboid protozoa. For diagnostic confirmation and species-level identification, polymerase chain reaction was performed on frozen tissues from six animals, targeting the amplification of a 109 bp fragment of the E. invadens 18S rRNA gene. Based on the pathological and molecular findings, along with protozoan species identification, a definitive diagnosis was established. Although amebiasis has been reported previously in reptiles, including red-footed tortoises, this is the first description in black-bellied sliders. This study highlights the importance of amebiasis as a cause of morbidity and mortality in captive testudines.
Locomotor disorders in pigs involve both infectious and non-infectious causes; however, iatrogenic peripheral neuropathies are rare. This study describes clinical, macroscopic and histological alterations associated with an outbreak of chronic neuritis in piglets following intramuscular drug administration on two farms. In two farms, each with 500 sows, approximately 7% of farrowing house piglets (26/370) presented with a plantigrade posture of the left pelvic limb (LPL) beginning on the third day of life, with no clinical improvement despite treatment. Nine piglets were subjected to necropsy. On gross examination, an off-white thickening involving the branches of the common fibular nerve of the LPL (indicative of fibrosis) was observed. On microscopic examination, Masson's trichrome and haematoxylin and eosin staining revealed granulomatous inflammation and abundant fibrovascular connective tissue between nerve fascicles, many of which were atrophied or undergoing degeneration. The anatomopathological findings were consistent with chronic (22.2%) and chronic-active (77.8%) neuritis and perineuritis associated with denervation-induced muscular atrophy, predominantly affecting the gastrocnemius muscle, which resulted in the plantigrade posture. Considering the location and pattern of the histological lesions, as well as the history of intramuscular injections during the first days of life, the lesions were considered to be of iatrogenic aetiology.
Tracheal disorders are uncommon in animals. Among congenital anomalies, segmental or complete absence of tracheal rings is described rarely in humans and in animals even less frequently. This report describes the clinical, gross and histopathological features of two cases of segmental absence of tracheal rings in cats and briefly reviews tracheal disorders. Cat 1 was a 1-year-old male mixed breed (Domestic Shorthair) that presented with a history of trauma and pneumothorax, followed by persistent respiratory distress and death despite treatment. Cat 2 was a 3-year-old male stray mixed breed (Domestic Shorthair) admitted with severe dyspnoea that died before therapy could be initiated. At necropsy, both cats showed an absence of cartilaginous rings in the distal third of the trachea, approximately 2 cm cranial to the carina. The affected segments measured 1 cm (cat 1) and 2 cm (cat 2) in length, with moderate to marked narrowing of the lumina. Cat 1 also had marked emphysema in the perirenal adipose tissue. Histologically, the cartilaginous rings were completely absent and replaced by vascularized fibrous connective tissue infiltrated by a small number of mixed inflammatory cells and loss of the respiratory epithelium in the affected segments. Pulmonary lesions included alveolar emphysema, congestion, haemorrhage and oedema in cat 1, and atelectasis, congestion and alveolar oedema in cat 2. Segmental absence of tracheal rings in cats appears to occur predominantly in the distal third of the trachea. Although rare, it should be considered as a differential diagnosis in cats presenting with respiratory distress.
A 9-month-old unsterilized female Swiss mouse (Mus musculus), housed in the Central Animal Facility of the Federal University of Mato Grosso, presented with a 1-month history of progressive abdominal distention. Occupying most of the abdominal cavity was a prominent oval-shaped, 30 g (constituting 38% of the bodyweight), 4.5 cm × 3.5 cm × 3.2 cm nodule with an irregular surface that was compressing the liver, diaphragm and thoracic cavity cranially, the right kidney laterally and the intestinal loops caudally. Histological examination confirmed a multilocular paraovarian cyst closely resembling the giant paraovarian cysts described in women. Paraovarian cysts should be suspected as a differential diagnosis in cases of marked abdominal distention in mice.
Mitotic count is a key parameter of the cytological evaluation of canine lymphomas (CLs), but consensual guidelines for counting are missing. Variations in cell preservation are common in cytological smears and this can compromise the reproducibility of mitotic counting. We compared three methodologies for selecting fields for mitotic counting in CL cytological smears and interobserver agreement was assessed. Mitotic counting was performed in 19 CLs by three observers in five high-power fields (HPFs), selected according to the following methodologies: (A) randomly and with well-preserved cells; (B) adjacent fields within the best-preserved monolayer area; and (C) in the area with the highest mitotic activity (hot spots). Counts were analysed both as the total number in five HPFs and as number per mm2; using published cut-off values, mitotic counts were classified as low, intermediate or high. Counts by methods A and B were comparable, while consistently higher values were obtained with method C. Overall, the mitotic count classification shifted in 21% of the cases, with a higher assignment of cases to the high category using method C. Interobserver agreement was poor between observers using microscopes with different field of view diameters. When counts were normalized to number per mm2, the agreement improved. The methodology of counting in adjacent fields showed better interobserver agreement compared to random fields. However, there was a high variability in the recorded numbers by each observer in highly proliferative CLs. The data highlights that mitotic counts in cytological smears of CL are highly dependent on methodology for selection of the fields and on the microscope.
Hystricomorphs, such as guinea pigs (Cavia porcellus), degus (Octodon degus) and chinchillas (Chinchilla lanigera), have become increasingly popular pet animals in Japan. However, comprehensive data on diseases in these animals remain limited, primarily restricted to single case reports, except for guinea pigs. The present study aimed to investigate the frequency of neoplastic and non-neoplastic diseases in pet guinea pigs, degus and chinchillas in Japan and to describe their epidemiological characteristics. We reviewed biopsy samples from guinea pigs (n = 134), degus (n = 57) and chinchillas (n = 16) collected at the Miwa Exotic Animal Hospital and the Laboratory of Veterinary Pathology, University of Tokyo, between 2006 and 2020. The most common condition in guinea pigs was integumentary disorders (n = 83; 61.9%), with mammary carcinoma (n = 41; 49.1%) being the most prevalent. The second most common condition was female reproductive disorders (n = 43; 32.1%), with ovarian cysts (n = 11; 25.6%) the most frequent. In degu samples integumentary disorders (n = 23; 40.3%) were the most common, followed by respiratory disorders (n = 22; 38.5%). Soft tissue sarcoma (n = 15; 65.2%) was the most frequently observed integumentary disorder, while fibroma with bone formation (n = 10; 45.4%) was the most prevalent respiratory disorder. In chinchilla samples female reproductive disorders (n = 13; 81.2%) were the most common, with endometritis being the most frequent (n = 5; 38.4%). The frequency of disorders peaked at 3-4 years old in guinea pigs and degus. No age-specific peaks were observed in chinchillas. This is the largest retrospective histopathological study on degus and chinchillas to date and the findings provide valuable insights for veterinarians treating hystricomorphs.
Amyloidosis is a group of disorders characterized by the deposition of misfolded proteins within the body, with disease subtypes classified based on the precursor protein. With the increasing longevity of captive animals, several forms of age-related amyloidosis have been reported in recent years, and attention to this disease in the welfare of aged animals has been growing. Here, we report a case of amyloidosis in a 14-year-old Shetland Sheepdog involving three age-related amyloid types. Histopathological analysis, mass spectrometry-based proteomic analysis and immunohistochemistry revealed fibrinogen Aα-chain-derived amyloid deposited in the vascular walls of the liver, glomeruli of the kidney, cardiac mitral valve, coronary artery walls and myocardial interstitium; apolipoprotein A-I-derived amyloid deposited in pulmonary vascular walls and alveolar septa; and EGF-containing fibulin-like matrix protein 1-derived amyloid deposited in the submucosa and vascular walls of the gastrointestinal tract. All three of these amyloidoses have been documented as age-related amyloidosis in animals, suggesting that ageing may also have contributed to the development of triple amyloidosis in this case. This study highlights the diversity of amyloidosis in aged dogs and emphasizes the importance of accurate organ-specific typing of amyloids.
Proliferative enteropathy is a common infectious disease affecting pigs, horses and other animals; it is caused by Lawsonia intracellularis, an obligately intracellular bacterium. Lawsonia infection causes a distinctive pathological change, characterized by a rugose thickening of the intestinal mucosa, due to the adenomatous proliferation of immature intestinal crypt epithelial cells, with local depletion of goblet and enteroendocrine cells. The disease has a low infectious dose; transmission occurs readily between young animals via oral contact with infected faecal material derived from other infected animals and the environment. Intracellular L. intracellularis infection causes the transient amplifying epithelial cells in the crypts of the aboral intestine to fail to differentiate, leading to the distinctive adenomatous proliferation. This differentiation failure reflects Lawsonia's ability to disrupt paracrine crosstalk signalling between epithelial cells and the layers of supporting cells surrounding each crypt. A working hypothesis is that the intracellular infection of transient amplifying cells in the crypt by Lawsonia disrupts the quiescence activity of bone morphogenetic protein at the crypt-villus junction zone. Lawsonia infection is a rare example of host tissue hyperplasia due to a reaction induced by a bacterium.
Testicular involvement in cats with lymphoma is poorly documented, and its clinical importance remains unclear. Here, we present a case with concurrent gastrointestinal and bilateral testicular lymphoma, which was evaluated using fine-needle aspiration (FNA) cytology and polymerase chain reaction for antigen receptor rearrangements (PARR). Cytological evaluation of both lesions revealed a monomorphic population of immature lymphoid cells with features consistent with lymphoma. PARR targeting T- and B-cell receptor gene rearrangements, performed to further characterize the lesions, did not reveal monoclonal lymphoid proliferation at either site. The lack of confirmatory evidence with PARR highlights the limitations of clonality testing for FNA-based diagnosis, particularly in cases with minimally invasive sampling. The present case highlights the fact that lack of clonality does not conclusively exclude lymphoma and emphasizes the need for caution when interpreting clonality findings when diagnosis relies on minimally invasive sampling.
Dandy-Walker malformation (DWM) is a rarely reported constellation of congenital cerebellar and skull abnormalities that, in humans, traditionally includes cerebellar vermis hypoplasia (or agenesis), a malformed dilated and often cystic fourth ventricle and enlargement of the posterior cranial fossa (caudal cranial fossa in veterinary species). This combination of anomalies commonly causes hydrocephalus, leading to neurological signs. DWM is thought to arise from disrupted embryogenesis of the rhombencephalic alar plate, either spontaneously or following teratogenic exposure. Secondary anomalies, such as brainstem nuclei malformations or hypoplasia, are occasionally described in association. DWM occurs infrequently in humans and has rarely been reported in veterinary species. Clinical signs commonly described in veterinary species include abnormal gait, non-progressive cerebellar ataxia, nystagmus, unilateral or bilateral absence of the menace reaction and seizures. Here, we describe a 1-day-old, 30 kg, bovine male Angus calf that was delivered by a healthy heifer and euthanized due to neurological signs. Clinically, the calf was laterally recumbent with positional nystagmus and absent palpebral reflexes. Post-mortem brain examination confirmed agenesis of the cerebellar vermis and severe dilatation of the fourth ventricle. This case report documents the gross and histopathological features of DWM in a bovine neonate and summarizes the current veterinary literature.
Oral osteosarcoma accounts for a significant proportion of axial osteosarcomas. Telangiectatic osteosarcoma is a rare and aggressive osteosarcoma subtype that consists of blood-filled spaces that may be difficult to differentiate from aneurysmal bone cysts and haemangiosarcomas. Here we describe the clinical, histological and immunohistochemical features of nine oral telangiectatic osteosarcomas and four oral haemangiosarcomas in dogs. Medical records and histological samples were reviewed and immunohistochemistry (IHC) for RUNX2 and CD31 was performed on all cases. Oral telangiectatic osteosarcomas occurred in five castrated male dogs, three spayed female dogs and one female dog of different breeds with a median age of 11 years. Tumours consisted of rapidly growing, ulcerated and occasionally haemorrhagic oral masses involving the maxilla, mandible or gingiva. Histologically, neoplasms were infiltrative and composed of pleomorphic neoplastic cells forming blood-filled spaces admixed with solid bundles and irregular osteoid. All cases had strong nuclear RUNX2 immunolabelling and lacked CD31 immunolabelling. Haemangiosarcomas occurred in four spayed female dogs of multiple breeds with a median age of 9.4 years. Clinical signs consisted of oral bleeding from red and/or ulcerated tumours arising from the right maxilla, left mandible and right mandible. Haemangiosarcomas were composed of vascular channels lined by CD31-positive endothelial cells, with no osteoid or RUNX2 labelling. Oral telangiectatic osteosarcoma is a rare osteosarcoma subtype with histological features that resemble those of haemangiosarcomas, which can complicate the diagnosis, particularly in small biopsies. The combined use of histology and IHC (RUNX2 and CD31) supports reliable differentiation between these neoplasms.
Yersinia pseudotuberculosis is a zoonotic pathogen that has been recovered from a variety of companion, production, laboratory, wildlife and avian species. The prevalence of this bacterium varies geographically but is generally considered widespread within the terrestrial environment with human exposure principally by ingestion of contaminated food or water. Pseudotuberculosis, due to Y. pseudotuberculosis, is a common cause of mortality in captive exotic birds and mammals and, according to the OIE WAHIS-Wild Interface, is the 8th most frequently reported disease/infection for all wildlife worldwide and the 5th in wild mammals. This report increases the number of recognized species susceptible to pseudotuberculosis and expands the environmental distribution of this bacterium into the marine habitat with four Y. pseudotuberculosis culture-positive cases in three odontocete species, including three from the North Sea and one from the northeastern Pacific Ocean. This case series is the first to report pseudotuberculosis in mammals that reside exclusively in the marine habitat. At present, there is insufficient information on the natural history of Y. pseudotuberculosis and marine mammal infections to infer whether exposure was due to terrestrial contamination of water courses or, alternatively, the bacterium persisting within the marine environment.
A 12-year-old neutered male Domestic Shorthair Cat, negative for feline immunodeficiency virus and feline leukaemia virus, was presented to the veterinary hospital with a 3-week history of anorexia, lethargy, abdominal pain and intermittent vomiting. Abdominal ultrasonography revealed a heterogeneous, poorly demarcated mass in the right mesogastric region, involving the pancreas and adjacent organs. Cytological evaluation of the abdominal fluid revealed a neoplastic effusion consistent with carcinomatosis. Given the poor prognosis, the cat was euthanized and submitted for necropsy, which revealed a large volume of free transudate within the abdominal cavity. In the pancreas, there was a 6.0 × 3.0 × 7.5 cm, irregular, soft, white-to-yellow mass and multiple small, firm, white nodules, ranging from 0.1 cm to 1 cm in diameter, were adhered to the omentum, mesentery, diaphragm and abdominal wall and to the serosal surfaces of the urinary bladder, intestines, spleen, stomach, liver and lungs. Microscopically, the pancreas contained a neoplastic proliferation composed predominantly of round cells arranged in loosely cohesive groups. Similar neoplastic proliferations were observed in the peritoneum, diaphragm, omentum and mesentery, the serosal surfaces of the urinary bladder, intestines, spleen, stomach, liver, left adrenal gland and lungs, and in the mediastinal lymph nodes. Based on these findings, the histopathological diagnosis was metastatic undifferentiated pancreatic neoplasia. Immunohistochemical evaluation revealed strong, diffuse cytoplasmic immunolabelling for vimentin and ionized calcium-binding adaptor molecule 1 in the neoplastic cells, with no labelling for pancytokeratin (AE1/AE3), E-cadherin, CD3 and CD20. The gross, histological and immunohistochemical findings were consistent with a histiocytic sarcoma of probable pancreatic origin, with metastatic dissemination throughout the peritoneum resembling that observed in primary pancreatic carcinomatosis. Histiocytic proliferative disorders are rare in cats, and the unusual presentation of this case provides an important contribution to the recognition of the possible manifestations of histiocytic sarcomas in this species.
Molecular mimicry is hypothesized to play a key role in the pathogenesis of acute polyradiculoneuritis (APRN) in dogs, as in Guillain-Barré syndrome (GBS). GBS is linked to Campylobacter jejuni and cytomegalovirus, while Parvovirus B19 shows temporal and serological associations. In dogs, the cause of APRN is often unknown, although recent vaccination or ingestion of raw poultry contaminated with Clostridium perfringens is documented. Antiganglioside antibodies are potential serum biomarkers for APRN. Eight 2.5-month-old Sprocker littermates and a 3-month-old female Cockapoo developed severe gastrointestinal clinical signs and tested positive for canine parvovirus-2 (CPV-2) infection. Six littermates died, while two pups (one male, one female) and the Cockapoo recovered. Seven days later, the male puppy developed pelvic limb weakness progressing to flaccid tetraparesis over 24 h, followed by thoracic limb contracture. Both female pups, 10 days after recovering from illness, developed neuromuscular clinical signs that deteriorated for 9 days before improving. They presented with a short-strided, choppy gait with kyphosis, and the Cockapoo developed dysphonia. Both female puppies improved over several months. Antiganglioside antibodies were not detected in the two littermates at 1 and 3 months after clinical onset. Treatment included supportive care. Both littermates received prednisolone and methocarbamol, with only the female responding. The male was euthanized due to poor quality of life. Post-mortem examination revealed widespread muscular atrophy and axonal degeneration, with active regeneration detected on semi-thin tissue sections of nerves. This study described a peripheral neuropathy temporally associated with CPV-2 infection. Although a causal relationship cannot be established, the clinical course and pathological features are compatible with a post-infectious neuromuscular process.
Canine prostate carcinoma (cPCA) is an aggressive malignancy with limited prognostic markers. This study aimed to comprehensively characterize immune-cell infiltration, glycolysis, hypoxia and oncogenic markers in cPCA and assess their clinical relevance. Tumour tissues from 26 dogs with cPCA and hyperplastic prostate tissues from seven dogs were analysed using immunohistochemistry. Five immune cell markers (CD3, CD20, CD8, Foxp3 and CD204) were quantitatively assessed, and the amounts of immunolabelling of monocarboxylate transporter 4 (MCT4), glucose transporter 1 (GLUT1), human epidermal growth factor receptor 2 and Ki-67 were evaluated through established scoring methods. Associations between progression-free survival and overall survival were analysed using univariate Cox regression. All tumours were infiltrated by multiple immune-cell subsets, characterized by marked intertumoral heterogeneity. Immune-cell densities were generally higher in cPCA than in hyperplastic prostate tissue. Compared with hyperplastic prostate tissue, cPCA showed lower MCT4 and higher GLUT1 expression. No significant associations were observed between immune-cell density or marker expression and clinical outcomes. The findings suggest that cPCA has widespread immune-cell infiltration and distinct metabolic features; however, individual immunohistochemical markers alone were insufficient to predict clinical outcomes.
A pigmented dermal duct tumour was diagnosed in a 12-year-old female ring-tailed lemur (Lemur catta) kept in a zoo. The tumour developed on the ventral surface of the left fourth digit and appeared as a black, solid, ulcerated nodule. Histologically, it was a well-demarcated, non-encapsulated dermal proliferation of basaloid neoplastic epithelial cells forming solid nests with scattered small duct-like lumina. Scattered melanocytes and abundant melanin pigment were present within the tumour. There was no continuity between the tumour and the epidermis. Immunohistochemically, the basaloid neoplastic epithelial cells were positive for pan-cytokeratin and p63 but negative for cytokeratin 19, α-smooth muscle actin, vimentin, Sox10, DOG1, S100, PNL2 and Melan-A. Neoplastic luminal cells were positive for pan-cytokeratin and cytokeratin 19, but negative for p63. Based on the morphological and immunohistochemical findings, the tumour was diagnosed as a pigmented dermal duct tumour that corresponds to one of the subtypes of benign human poroid neoplasms. To our knowledge, this is the first report of this neoplasm in a ring-tailed lemur.
Proliferative enteropathy is a common infectious disease affecting pigs, horses and other animals; it is caused by Lawsonia intracellularis, an obligately intracellular bacterium. Lawsonia infection causes a distinctive pathological change, characterized by a rugose thickening of the intestinal mucosa, due to the adenomatous proliferation of immature intestinal crypt epithelial cells, with local depletion of goblet and enteroendocrine cells. The disease has a low infectious dose; transmission occurs readily between young animals via oral contact with infected faecal material derived from other infected animals and the environment. Intracellular L. intracellularis infection causes the transient amplifying epithelial cells in the crypts of the aboral intestine to fail to differentiate, leading to the distinctive adenomatous proliferation. This differentiation failure reflects Lawsonia's ability to disrupt paracrine crosstalk signalling between epithelial cells and the layers of supporting cells surrounding each crypt. A working hypothesis is that the intracellular infection of transient amplifying cells in the crypt by Lawsonia disrupts the quiescence activity of bone morphogenetic protein at the crypt-villus junction zone. Lawsonia infection is a rare example of host tissue hyperplasia due to a reaction induced by a bacterium.
Osteosarcoma is a malignant osteogenic tumour of mesenchymal origin and is the most commonly reported neoplasm primarily affecting the appendicular skeleton in dogs and cats. When there is no involvement of bones, and the soft tissue is the primary site of the neoplasia, it is known as extraskeletal osteosarcoma (EOS). EOS is well documented in dogs and cats but is rarely reported in non-domestic species. Microscopically, an osteosarcoma is characterized by neoplastic proliferation of mesenchymal cells with production of osteoid matrix or immature bone. The aim of this study is to report two cases of EOS in guinea pigs (Cavia porcellus), as well as to identify and correlate clinical, radiographic, pathological and immunohistochemical findings. In case 1, multiple mesenteric and pancreatic nodules were present. Case 2 had a large subcutaneous mass with pulmonary and renal metastases. In both cases, radiographs revealed soft tissue masses with mineralized areas but no skeletal involvement. Histological examination confirmed malignant mesenchymal proliferation with osteoid deposition. Immunohistochemistry was applied, with the caveat that there are no specific immunohistochemical markers for definitive diagnosis of osteosarcoma. The neoplastic cells in both cases were strongly immunopositive for vimentin and RUNX2. The cases showed variable immunolabelling for S100 and alpha-smooth muscle actin, Ki-67 and p63. These cases enhance the clinicopathological spectrum of EOS in guinea pigs and highlight the importance of combining radiographic, histopathological and immunohistochemical evaluation for accurate diagnosis.
