An intact 16-month-old female Entlebucher Mountain Dog in poor general condition was presented with clinical signs of gastrointestinal disease. Abdominal ultrasonography revealed a mass in the right kidney. Nephrectomy combined with ovariohysterectomy was performed. Histology revealed a mesenchymal tumour that was composed of neoplastic spindle cells forming interlacing fascicles, whorls and bundles, and embedded into a loose myxoid to dense collagenous stroma. Immunohistochemically, neoplastic cells diffusely labelled for vimentin and partially for S-100 protein and p75. Based on these results, the tumour was diagnosed as a classical variant of a congenital mesoblastic nephroma. The expression of p75 has not been described in this tumour entity before and its significance with regard to tumour promoting or tumour suppressing function or indication of a neurogenic differentiation remains undetermined. After a 3-year follow-up the dog was clinically healthy, indicating a successful surgical treatment.

Retroperitoneal neoplasms are rare in both human and veterinary medicine, particularly in cats, where they account for less than 0.1 % of all neoplasms. This report describes a rare case of retroperitoneal T-cell lymphoma in a 7-month-old, feline leukaemia virus (FeLV)-positive Domestic Shorthair cat, leading to urethral and intestinal obstruction and subsequently cystitis and megacolon, respectively. The cat presented with clinical signs of weight loss, vomiting, tenesmus and urinary retention, and was diagnosed with a retroperitoneal mass compressing the colon and the urinary bladder. Due to the poor prognosis, the cat was euthanized during an exploratory laparoscopy and submitted for post-mortem examination. At necropsy, there was a large retroperitoneal, white, soft-to-firm, irregular mass that encompassed and compressed the rectum, colon, urethra and urinary bladder neck, along with megacolon and haemorrhagic cystitis. Histologically, the mass consisted of sheets of medium-sized neoplastic lymphocytes with mild anisocytosis and anisokaryosis. In the urinary bladder, a necrohaemorrhagic cystitis was observed. The cytoplasm of the neoplastic lymphocytes was positive by immunolabelling for CD3; therefore, the neoplasm was classified as a lymphoblastic T-cell lymphoma. Additionally, multifocal cytoplasmic FeLV immunolabelling was observed within the neoplastic cells, suggesting a possible viral involvement in the case's oncogenesis. This is the first reported case of a possibly FeLV-related retroperitoneal lymphoma in a cat. It had both intestinal and urinary tract obstructions as clinical outcomes. Our findings highlight retroperitoneal lymphoma as a new differential diagnosis for cats with lower urinary tract and gastrointestinal tract obstructions.

Congenital malformations affecting the lower respiratory tract of non-human primates are extremely rare, with only a few published reports. We report a complex case of multiple congenital lung malformations in a 1-year-old female black-capped Bolivian squirrel monkey (Saimiri boliviensis boliviensis) that died following an anaesthetic procedure for tattoo placement. At necropsy, the left lung lobes had severe pulmonary hypoplasia. The left medial lung lobe had a long stalk that ended with multiple air-filled cysts and bullae, characteristic of congenital lobar emphysema. Histologically, at the margin of the left cranial lung lobe was a 2 mm diameter mass composed of multiple cystic structures lined by a cuboidal epithelium and supported by thick trabeculae of myxoid stroma and dense connective tissue containing capillaries. The histological morphology of the mass was consistent with congenital pulmonary airway malformation type 4, an exceedingly rare condition in both human and veterinary medicine.

The occurrence of vaginal calculi is rare in animals. This report describes the first record of a vaginal calculus in an adult captive red-rumped agouti (Dasyprocta leporina). The specimen presented with a swelling in the genital region, which was firm and mobile on palpation. Direct examination revealed a calculus occupying the entire vaginal cavity. Surgical intervention consisted of a ventral vulvar incision and direct removal of the calculus, followed by appropriate suturing of the musculature, subcutaneous tissue and skin. The agouti showed good clinical recovery, with proper wound healing and return to normal physiological conditions. Post-operative abdominal ultrasonography ruled out urinary tract alterations, suggesting an exclusively vaginal origin of the calculus. Chemical analysis of the calculus revealed a mixed composition of calcium carbonate, calcium oxalate, calcium phosphate (hydroxyapatite) and ammonium-magnesium phosphate (struvite). This report highlights the importance of recognizing the occurrence of vaginal calculi in agoutis and of including them in the differential diagnosis of clinical signs such as urinary incontinence, pollakiuria, haematuria and genital swelling.

Polyclonal B-cell lymphocytosis of English Bulldogs (PBLEB) is a lymphoproliferative disorder associated with splenomegaly and hyperglobulinaemia. Information regarding both the degree of expected lymphocytic organ infiltration and possible treatment protocols is limited, and clinical overlap with neoplastic lymphoproliferative disease presents a diagnostic challenge. Here, we report and discuss the case of a 5-year-old English Bulldog with PBLEB, presenting with a marked gammopathy, marked splenomegaly and subsequent abdominal distension resulting in gastrointestinal clinical signs. We present extensive clinicopathological and histopathological data, demonstrate marked infiltration of tissues including the bone marrow, and document a favourable clinical outcome following splenectomy.

Splenic neoplasm is frequently diagnosed in dogs and can present as nodules or splenomegaly. This retrospective study aimed to characterize the gross features of splenic neoplasm in dogs at necropsy in order to recognize possible presentation patterns for each diagnosis. In a 10.5-year period, 1,187 dogs underwent necropsy with a confirmed diagnosis of neoplasia, of which 262 had splenic neoplasm. Three dogs had two distinct concurrent tumours, totalling 265 splenic neoplasms. Of these, non-angiogenic tumours were diagnosed in 217 cases (81.9 %) and angiogenic neoplasms were diagnosed in 48 cases (18.1 %). Most non-angiogenic neoplasms were metastatic (50.2 %), mainly epithelial and round cell in origin, with multifocal, red to white nodules, followed by multicentric (31.8 %) and primary (18 %) tumours. Lymphoma was the main multicentric neoplasm, often with splenomegaly associated with micronodular or nodular pattern. Most primary tumours were stromal sarcomas, which often exhibited focal nodules. Haemangiosarcoma was the most common angiogenic neoplasm, frequently with multifocal red nodules in multiple organs. Angiogenic tumours and primary non-angiogenic tumours were significantly larger than multicentric and metastatic tumours, but no statistical difference was observed. These findings indicate that although gross overlap among splenic tumour types persists, certain macroscopic patterns, such as focal nodules in stromal sarcomas, multifocal nodules in haemangiosarcomas and larger size of angiogenic and primary non-angiogenic neoplasia, may help guide initial differential diagnoses.

The rete testis forms from the mesonephric tubules in a series of interconnected channels in which spermatozoa travel in a high volume of fluid between the seminiferous tubules and efferent ductules. Cystic rete testis can be identified by uni- or multilocular cysts with a wall lined by low cuboidal epithelial cells and a dense fibrous stroma. An 11-year-old male central bearded dragon (Pogona vitticeps) was evaluated for a coelomic mass. The animal had no other clinical signs apart from coelomic mass effect. Exploratory surgery revealed a mass in the region of the right testis that was excised and submitted for histology. The central bearded dragon had no post-operative clinical abnormalities. Grossly, the 6-cm diameter, smooth, yellow mass was composed of numerous, 0.5-3.0-cm diameter cysts filled with yellow fluid. Histologically, the cysts were lined by simple cuboidal to flattened epithelial cells that rarely formed small tufts or papillary projections. Cyst lumina occasionally connected with seminiferous tubules, approximately 10 % of which were dilated and all of which had normal spermatogenesis. Epithelial cells had a small amount of eosinophilic, slightly vacuolated cytoplasm, rare apical cilia and basilar, round nuclei with coarse chromatin and small, distinct nucleoli. This is the first description of a cystic rete testis in a reptile or any non-mammalian species. Cystic rete testis can be primary or secondary to obstruction of the efferent ductules or epididymis. The lack of inflammation and absence of diffuse dilation of the seminiferous tubules suggest that spermatozoa were able to escape, consistent with primary cystic rete testis.

Epidermal growth factor-containing fibulin-like extracellular matrix 1 (EFEMP1)-derived amyloidosis causes gastrointestinal bleeding in humans. Amyloidosis has also been reported in the Tsushima leopard cat (Prionailurus bengalensis euptilurus) and rhesus macaque (Macaca mulatta). However, the clinical signs and lesions in humans and animals differ. A captive Tsushima leopard cat, aged 19 years, died of haemorrhage due to a gastric ulcer and a pathological analysis was performed. Amyloid was deposited in the venous walls and interstitium of the systemic organs, especially the stomach and intestines. The amyloid appeared as a weakly basophilic hyaline-like substance and stained with Congo red. Immunohistochemistry and liquid chromatography-tandem mass spectrometry revealed that the amyloid was composed of both N- and C-terminal EFEMP1 peptides. The amyloid fibrils were approximately 10 nm wide, unbranched, short and randomly arranged. The patient died from gastric bleeding caused by EFEMP1-derived amyloidosis. These findings suggest that EFEMP1-derived amyloidosis in Tsushima leopard cats has pathological features similar to those in affected humans, including amyloid deposition predominantly in the walls of veins and fatal gastrointestinal bleeding.

Lingual neoplasms comprise approximately 2-4 % of canine oropharyngeal tumours, with liposarcomas being particularly rare and typically arising in the subcutis of the extremities and trunk. This report describes a 5-year-old spayed female Bedlington Terrier that presented with a ruptured lingual mass with muscular invasion, for which glossectomy was performed. Histopathological examination revealed a neoplastic proliferation of well-differentiated adipocytes that infiltrated the skeletal muscle layer. The deeper portion of the mass had dedifferentiation of adipocytes and malignant transformation into liposarcoma. The dedifferentiated neoplastic spindle cells contained cytoplasmic lipid vacuoles that stained positively with Oil Red O and had marked pleomorphism and elevated mitotic activity. Immunohistochemically, the neoplastic cells were positive for S100 and negative for CD34. While prior studies have suggested that liposarcomas do not originate from the malignant transformation of lipomas, the findings in this case support the possibility of infiltrative lipoma undergoing malignant transformation into a dedifferentiated and aggressive liposarcoma. This case underscores the potential for benign lipomatous lesions to evolve into their malignant counterparts under certain pathological conditions.

Beak neoplasia is a rare condition in avian species and is most often reported within the order Psittaciformes. Through a multi-institutional retrospective study, we describe nine cases of beak neoplasia from six species belonging to the orders Galliformes (Gallus gallus domesticus and Syrmaticus reevesii), Psittaciformes (Amazona sp and Ara sp), Anseriformes (Anas platyrhynchos domesticus) and Columbiformes (Columbina livia domestica). The sex distribution was four females, four males and one not specified. The average age at the time of diagnosis was 11.8 years (range 2-38 years; standard deviation ± 12.8 years). The most commonly reported tumour was squamous cell carcinoma, followed by melanoma; metastases were documented in both neoplasms. Other diagnosed neoplasms included undifferentiated carcinoma, lipoma and fibrosarcoma. Most neoplasms were located at the maxillary rhamphotheca (66 %; 6/9). Clinical signs included chronic weight loss, anorexia, hyporexia, inappetence, dysphagia, extensive ulceration of the beak keratin, secondary bacterial infection, halitosis, crop impaction and dyspnoea. The progression of neoplasms affecting the beak varied from 3 weeks to several years, leading to euthanasia in 55 % (5/9) of the cases.

We report a rare case of association of mesenteric volvulus and left hepatic hypoplasia in an approximately 6-year-old, uncastrated male German Shepherd Dog. The small and large intestines were displaced from their normal anatomical position and intensely dilated, with diffusely hyperaemic and haemorrhagic serosae. The mesenteric root, at its insertion into the roof of the abdominal cavity, was twisted 360° counterclockwise along its axis. The small and large intestines had thick, haemorrhagic and oedematous walls, with liquefied, bloody and fetid contents throughout. The left medial and lateral hepatic lobes and the caudate process of the caudate lobe were markedly reduced in size, while the right medial lobe was slightly enlarged, indicating left hepatic hypoplasia with mild compensatory right-sided hypertrophy. Intestinal samples tested negative for Clostridioides difficile, Salmonella spp, canine parvovirus, Giardia spp and Campylobacter spp. Microscopic analysis revealed diffuse necrosis of the mucosa and marked diffuse haemorrhage in the intestines, with preservation of crypts. In the lamina propria, a mild lymphoplasmacytic infiltrate was present, along with some intact and degenerated neutrophils. The only histological difference observed between the hypoplastic and normal hepatic lobes was moderate biliary hyperplasia and hypertrophy. Based on the macroscopic findings, the diagnosis of mesenteric volvulus and left hepatic hypoplasia was confirmed, both of which are considered rare in dogs. The severity of the hepatic hypoplasia may have predisposed to mesenteric volvulus.

The development of neoplasms in giant anteaters (Myrmecophaga tridactyla) is poorly documented, with most studies focused on non-neoplastic changes. This report describes a case of chondrosarcoma in a 15-year-old male captive giant anteater that presented with lameness for approximately 6 months, locomotion difficulties and swelling of the left thoracic limb. After review of a radiograph, humane euthanasia was decided due to the poor prognosis and quality of life. At necropsy, a 17 × 20 × 13 cm mass was seen to project from the humeroradioulnar joint of the left thoracic limb. The mass was white, firm to soft, with translucent areas and moderate multifocal irregular cavitations. Histologically, it consisted of a poorly demarcated and partially encapsulated malignant mesenchymal neoplasm, arranged in irregular lobules of varying sizes containing hyaline cartilage. Immunohistochemical analysis revealed moderate immunolabelling of vimentin in neoplastic mesenchymal cells but no immunolabelling for pan cytokeratin. Based on the macroscopic, histopathological and immunohistochemical findings, a diagnosis of chondrosarcoma was established. This case emphasizes the importance of diagnosing diseases in captive species in which pathological conditions are rarely documented. This appears to be the first reported case of chondrosarcoma in a giant anteater.

A captive 10-year-old male North American river otter (Lontra canadensis) was evaluated for a 2-week history of weight loss and intermittent vomiting and regurgitation. Exploratory surgery identified a raised nodule on the quadrate lobe of the liver and an irregular nodule in the left limb of the pancreas. Partial lobectomy of the quadrate and right medial hepatic lobes was performed to excise the masses, and the pancreatic nodule was removed. Histological and immunohistochemical results were consistent with a glucagonoma that had metastasized to the liver. The otter received palliative care until 42 days postoperatively when it was humanely euthanized due to recurrence of clinical signs. Glucagonoma is a rare neoplasm in all species, with only a few cases reported in dogs, cats and horses. To the authors' knowledge there are no other reports of glucagonoma in mustelid species.

We document complex developmental anomalies of the cardiovascular system, including patent ductus arteriosus (PDA), additional pulmonary arteries, malformed interatrial septum (IAS), unconventional origin of the common brachiocephalic trunk (CBCT) and subclavian arteries, in a 1-week-old calf of the Indian Sahiwal breed. The PDA was comprised of a cylindrical tube of regular calibre. Additional pulmonary arteries originated from the pulmonary trunk immediately after the bifurcation into the pulmonary arteries. The IAS had the form of an inverted cone frustrum, which projected towards the left atrial chamber, with a wider opening towards the right atrium and a narrow opening towards the left atrium, and contained blood clots. The CBCT originated from the systemic aorta, with the right subclavian artery emerging as its first branch. Microscopic observation revealed that the PDA appeared similar to other blood vessels but with an uneven wall, resulting from a predominant smooth muscle cell population. The PDA had fewer internal cushions and less elasticity, suggesting a lower chance of conversion to the ligamentum arteriosum.

Vertebral column deviations, namely scoliosis, kyphosis, lordosis and combinations thereof, are poorly characterized in marine mammals. Here we present the clinical history and the post-mortem pathological and computed tomography (CT) scan analysis results on a 52-year-old captive female Antillean manatee (Trichechus manatus manatus) from Brazil. This animal had been kept at multiple small enclosures for most of its life. The main gross pathological and CT scan findings were severe thoracolumbar kyphoscoliosis that resulted in spinal canal stenosis and spinal cord compression. The adjacent thoracolumbar epaxial and hypaxial muscles were pale and atrophic. Acute and chronic myopathic changes, atrophy, as well as lipomatosis were confirmed microscopically. In this manatee, severe thoracolumbar kyphoscoliosis was probably triggered by captivity-related restricted mobility and postural and swimming alterations, including intermittent circling over decades. We surmise that postural, degenerative, spinal muscular/neuromuscular and muscle disuse atrophy occurred concurrently over time. These lesions probably resulted in sustained pain and could explain the behavioural alterations reported. This case sheds light on captivity-related vertebral column disease in sirenians and provides scientific evidence to inform housing recommendations for this taxon.

A 39-year-old female rhesus macaque (Macaca mulatta) presented for stertor that had progressed over a 2-year period. A mass involving the soft palate was seen partially obstructing the oropharynx. Histopathological examination revealed a well-circumscribed, partially encapsulated mass composed primarily of myoepithelial cells with scattered duct-like structures, squamous metaplasia and hyaline stroma. The mass was diagnosed as a myoepithelial-rich pleomorphic adenoma. To the best of our knowledge, this is the first reported case in non-human primates.

This study evaluated dental and temporomandibular joint (TMJ) pathology in North American wolverines (Gulo gulo luscus) from coastal southern Alaska, using 182 specimens (43.4 % females, 54.4 % male, 2.2 % unknown) collected across the 20th century. Among the individuals, 2.2 % were classified as young adults, 83.0 % as adults and 14.8 % had an undetermined age. High rates of dental diseases were identified, reflecting patterns seen in other wild carnivores, with acquired conditions occurring more frequently than congenital ones. Periodontitis was the most common pathology (98.9 %), with most cases showing mild severity (stage 2 = 98.9 %). Tooth fractures were identified in over two-thirds of the specimens, with deeper structural damage (complicated crown fractures = 26.2 %, complicated crown-root fractures = 23.1 %, root fractures = 31.3 %) observed more often than enamel fractures, likely due to typical biting behaviour. No significant differences in fracture prevalence were found between sexes (P = 0.3741). Enamel hypoplasia was rare (5.5 %), suggesting minimal systemic stress during dental development. Variations in root numbers were frequently noted (27.5 %), potentially reflecting an adaptive trait for dietary handling. Periapical lesions (9.9 %) were linked to pulp exposure (17.6 %, OR = 49.09, 95 % CI = 28.01-85.22, P <-0.0001), especially in the canine teeth, but were also seen in association with moderate to severe bone loss due to periodontitis (stages 3 and 4 = 65.9 %, OR = 7.75, 95 % CI = 2.20-24.80, P <0.0001). Attrition and abrasion were common (96.1 %), particularly affecting incisor and canine teeth, with a slightly higher incidence in females (U = 2,922, n = 79, n = 99, P = 0.0036), hinting at potential behavioural or dietary differences. TMJ pathology was uncommon (1.6 %) and mild, potentially suggesting that wolverine feeding habits may exert less stress on the joint compared to species with high bite-force diets. Overall, the observed dental and TMJ lesions align with patterns in other wild carnivores, suggesting similar environmental and behavioural influences. Future studies on dietary, genetic and longitudinal health factors could provide deeper insight into the dental adaptations and resilience of North American wolverines in their natural habitats.

Quadricuspid aortic valve (QAV) is a rare congenital heart condition in which the aortic valve is comprised of four, rather than three, sinuses and cusps. The clinical significance of QAV is unclear; it is diagnosed most frequently in humans and has not been reported in cattle. QAV was identified in three female Holstein cattle at necropsy for unrelated clinical conditions. Although heart murmurs were identified on clinical examination, no animal had heart failure. In all three cases the non-coronary cusp of the aortic valve was comprised of two separate cusps, resulting in a quadricuspid valve. Histological examination of the abnormal valves did not reveal consistent significant microscopic lesions. The clinicopathological consequences, genetic basis and incidence of QAV in cattle are unclear; however, veterinarians and pathologists should be aware of this condition as a possible differential diagnosis in cattle with heart murmurs.

In humans and cats, pancreatic carcinoma (PC) arising from the exocrine pancreas is considered an aggressive cancer associated with a poor prognosis due to its high metastatic rate. The aim of this retrospective multi-institutional study was to investigate tissue expression of biomarkers of tumour invasiveness, metastasis and immune escape in cats with PC. A secondary aim was to correlate the overall immunohistochemical scores (OISs) with histological characteristics, presence of metastasis and survival. Immunohistochemistry for COX-2, E-cadherin, CD44, c-KIT and PD-L1 was performed on 40 PC tissue samples. CD44 was expressed in all PCs with 27 (67 %) having a moderate to high OIS. PD-L1, E-cadherin, COX-2 and c-KIT expression was seen in 20 (50 %), 21 (52 %), 18 (45 %) and 14 (35 %) cases, respectively, with predominantly low OISs. Metastasis was present in 43 % of cats with a median survival time (MST) of 7 days (95 % CI 0-20; range, 1-1,094) and a 1-year survival rate of 13.8 %. When excluding cats that died or were euthanized at diagnosis, the MST was 19 days (95 % CI 0-99; range, 2-1,094). No statistical associations were found between COX-2, E-cadherin, PD-L1, CD44 or c-KIT OIS and histological subtype, necrosis, vascular invasion, mitotic count, presence of metastasis or survival. Positive E-cadherin expression was significantly associated with the presence of perineural invasion (P = 0.009; OR 1.50 [95 % CI 1.11-2.03]).