Melanoma is a rare neoplasm in small ruminants, particularly in sheep, and is uncommon in young animals. This study describes the clinical, cytological, histopathological, and immunohistochemical findings of a melanoma in a lamb. A three-month-old female sheep presented with a progressively growing mass in the left periauricular region, first observed at 45 days of age. Cytological evaluation revealed atypical cellular proliferation with marked pleomorphism and mitotic figures, suggesting a malignant neoplastic process. Imaging examinations demonstrated increased soft-tissue volume without evidence of bone involvement. Surgical excision was performed for both diagnostic and therapeutic purposes. Histopathological examination revealed a non-encapsulated, densely cellular, infiltrative neoplasm predominantly composed of epithelioid cells, with marked anisocytosis and anisokaryosis, a high mitotic index, intracytoplasmic melanin pigment, and areas of necrosis. Immunohistochemical analysis showed positive immunostaining for S100 and Melan-A, confirming the melanocytic origin of the neoplasm. Despite surgical removal, rapid local recurrence and clinical deterioration were observed, culminating in death within 30 days, indicating aggressive biological behavior and possible metastatic dissemination. This report demonstrates that, although rare in sheep, melanoma can occur in young animals and may progress rapidly, with a poor prognosis, highlighting the importance of an integrated diagnostic approach and its inclusion in the differential diagnosis of cutaneous masses in lambs.
Germ cell tumors can be classified as teratoma, embryonal carcinoma, yolk sac carcinoma, dysgerminomas and seminomas. Teratomas are composed by well-differentiated cells from at least two of the three embryonic layers, and are more commonly in ovaries or testicles, but can occur extragonadal. This case describes a subcutaneous mature teratoma in a 6-month-old kitten. Macroscopically, the tumor was multilobulated and firm, measuring 11 x 6,5 x 5cm; on cut surface, multiple cystic cavities, solid white areas and hard portions. Histologically, cells derived from the three layers were present – hair follicles and glands, nervous tissue, odontogenic epithelium, respiratory epithelium, and different mesenchymal cells (bone, adipocytes, muscle fibers and fibrous tissue). Immunolabeling for pancytokeratin, vimentin, GFAP and p40 were strong in the different types of cells, and no immature tissue was seen. So, the tumor was classified as a mature extragonadal teratoma. The mass was completely excised and no recurrence was seen.
This report describes the first known spontaneous case of B. coridifolia poisoning in a domesticated llama. In August 2023, the death of a 10-month-old female llama was reported on a farm in the Santa Catarina Plateau, Brazil. The affected llama had been acquired 2 months earlier from Paraná and initially kept with sheep on ryegrass pasture. One day before death, it was moved to a native field heavily invaded with B. coridifolia. Clinical signs included polydipsia and muscle tremors, progressing rapidly to death approximately 14 h after the onset of clinical signs. At necropsy, the 1st and 2nd gastric compartments (C1 and C2) contained abundant fibrous ingesta and exhibited mild mucosal congestion. In the 3rd gastric compartment (C3), mild to moderate congestion, predominantly affecting the caudal region, was observed. Histopathology revealed marked diffuse mucosal necrosis with inflammatory infiltrates predominantly composed of neutrophils and macrophages, and mild edema in the aglandular portions of C1 and C2. In C3, mild to moderate congestion was observed. Additional findings included pulmonary congestion and edema, renal congestion, and centrilobular hepatocellular degeneration. Specimens of B. coridifolia collected from the property were submitted to the Herbarium Lages of the State University of Santa Catarina (LUSC) for botanical confirmation. The epidemiological, clinical, and pathological findings supported the diagnosis of B. coridifolia (mio-mio) toxicosis.This case underscores the importance of proper pasture management and careful monitoring when relocating animals to areas containing known toxic plants.
Penile and preputial squamous cell carcinomas are among the most common tumors in horses, and inflammation of the external genitalia caused by Halicephalobus gingivalis is an important differential diagnosis. H. gingivalis is a free-living nematode that causes fatal parasitic encephalitis in horses and humans and can eventually be diagnosed in the kidneys, lymph nodes, lungs, genital and ocular mucosa. The objective was to characterize clinical and pathological lesions caused by H. gingivalis infection in the prepuce with concomitant involvement of penile squamous cell carcinoma in an equine. A 15-year-old male Pampa horse with prepuce and penis ulcerated lesions had these surgically excised. Histopathological analysis revealed granulomatous posthitis with H. gingivalis intralesional and ulcerated penile squamous cell carcinoma. The animal had a satisfactory clinical and surgical evolution, and there was no recurrence of the lesions after a six-month follow-up period. Considerations regarding the route of infection, treatment, and zoonotic potential were highlighted, showing the importance of including this pathogen in the differential diagnosis of nodular lesions affecting the preputial and penile areas in horses.
Diffuse immunoexpression of Preferentially Expressed Antigen in Melanoma (PRAME) is an ancillary diagnostic tool for distinguishing human melanoma from melanocytic nevi. Canine melanocytic neoplasms are common in veterinary diagnostic practice; however, no established immunohistochemical biomarkers of malignancy are currently available. This case series study aimed to investigate the immunoexpression of the anti-PRAME (EPR20330) antibody in canine melanocytic tumors. Two cutaneous melanocytomas and six melanomas from distinct anatomical sites (haired skin, oral cavity and feet) were submitted to immunohistochemistry protocol with anti-PRAME antibody (clone EPR20330, dilution 1:100, Abcam) overnight at 4°C. Nuclear immunolabeling was scored on a 5-point scale based on the percentage of positive tumor cells (0: none; 1: 1–25%; 2: 26–50%; 3: 51–75%; 4/diffuse: ≥76%). The two evaluated melanocytomas were PRAME-negative. All melanomas were PRAME-positive and diffuse nuclear immunolabeling was observed in 4/6 cases. To the best of our knowledge, this is the first study to demonstrate the immunohistochemical expression of the anti-PRAME antibody (clone EPR20330) in canine melanomas. Our preliminary findings, based on a limited sample size, suggest that PRAME may represent a promising ancillary diagnostic marker for these tumors, similar to its use in human samples. However, further studies with larger cohorts are needed to better characterize its labeling patterns in canine melanocytic neoplasms and to confirm its diagnostic value in veterinary pathology.
Porcine Respiratory Disease Complex (PRDC) causes substantial economic losses in swine production due to decreased efficiency and increased reliance on pharmaceuticals for disease control. Diagnosis of PRDC can be achieved by evaluating lung lesions at slaughterhouses, which enables assessment of herd health status and the formulation of targeted control strategies. In this study, the MADEC and SPES scoring systems were employed to characterize lung lesions associated with PRDC in pigs slaughtered in Colombia. A total of 16,223 red viscera (lungs, heart, and liver) from 15 commercially advanced farms were examined, utilizing the MADEC system for cranioventral consolidations and the SPES system for dorsocaudal pleuritis. Additionally, histopathological analyses and multiplex PCR tests were performed on randomly selected samples to identify microscopic lesions and respiratory pathogens. Approximately 70% of diaphragmatic lobes on both sides exhibited mild lesions (MADEC1), while severe lesions (MADEC3–4) were predominantly observed in the cardiac and accessory lobes. The prevalence of pleuritis was 17.7%, with SPES types 1 and 2 being most common. Glaserella parasuis was the only pathogen detected in the analyzed samples. Furthermore, concurrent use of up to five antimicrobial groups was documented across the farms. In conclusion, the observed respiratory lesions likely reflect the widespread circulation of PRDC agents, underscoring the need to enhance biosecurity, vaccination programs, and epidemiological surveillance in Colombian swine production. The adoption of standardized systems, such as MADEC and SPES, facilitates effective monitoring and control of respiratory diseases throughout the production chain.
The necropsy of pet birds is an important tool for determining the cause of death and for identifying potential zoonotic or non-zoonotic etiological agents related to fatality. This retrospective study (2014 to 2024) aims to identify the main causes of death in Psittaciformes kept under human care in the Jaboticabal/SP region, Brazil. A total of 146 necropsy cases and histopathological analyses archived at the Wildlife Pathology Service of São Paulo State University, Jaboticabal campus, were examined. The most prevalently analyzed species included Amazona aestiva, Nymphicus hollandicus, and Ara ararauna, with a higher prevalence of adult birds and those from household environments. Causes of death were classified into infectious and non-infectious processes. Metabolic conditions, such as atherosclerosis, were the leading cause of death (14.3%), followed by trauma and poisonings. Among infectious causes, parasites of the genus Paratanaisia, as well as bacterial and fungal infections, were prominent. Difficulties in isolating infectious agents and carcass autolysis limited some diagnoses. The study reinforces the importance of necropsy as a diagnostic tool and highlights the need for preventive management practices tailored to birds in households, breeding facilities, and zoos. The findings highlight the importance of monitoring pre-mortem factors and implementing targetd preventive medicine strategies to improve the well-being and longevity of captive Psittaciformes.
Myxoid mesothelioma is a rare variant of mesothelioma, characterized by a myxoid component, which refers to a gelatinous extracellular matrix containing mucin. This study describes a case of myxoid mesothelioma in a 13-year-old Yorkshire Terrier that presented with sudden abdominal distension, pain, and respiratory discomfort. Imaging exams revealed an extensive amount of amorphous, homogeneous, and viscous material in the abdominal cavity. Due to unsuccessful drainage attempts, exploratory laparoscopy was performed, uncovering large volumes of gelatinous material and areas of mesenteric thickness. Despite intensive care, the animal died post-surgery and was submitted for necropsy. Gross examination revealed diffuse gelatinous material coating the omentum and mesentery, along with firm micronodular areas. Microscopic analysis showed neoplastic sarcomatoid to round cells supported by delicate fibrovascular connective tissue with abundant myxoid stroma. Marked anisocytosis, anisokaryosis and cellular pleomorphism were observed; the myxoid nature of the stroma was confirmed by intense Alcian blue staining. Immunohistochemistry revealed positive vimentin and WT1 immunoreactivity, confirming the mesothelial origin of the tumor, while pancytokeratin, carcioembryonic antigen, high molecular weight cytoqueratin, and calretinin were negative. These findings support the diagnosis of myxoid-variant mesothelioma with clinical presentation of Pseudomyxoma peritonei.
Dilated cardiomyopathy (DCM) in dogs is a common hereditary primary myocardial disease affecting large and giant breeds, predominantly Doberman Pinschers. This pathology is associated with mechanical and electrophysiological dysfunction of the myocardium, which is manifested by inadequate ventricular eccentric hypertrophy. Our report focuses on the case of unusual systemic pulmonary collaterals in a Doberman Pinscher with DCM phenotype. Cardiologic data have shown that myocardial histologic changes may be secondary to the presence of pulmonary collaterals and their potential influence on the development of left ventricular volume overload. Thus, we had every reason to believe that the volume overload that caused the development of congestive heart failure in this dog and possibly sudden cardiac death was caused by the presence of a combined arterial malformation. This case illustrates that atypical bypass manifestations detected during echocardiography can be further evaluated using computed tomography and angiography to further characterize and identify concomitant vascular abnormalities that might otherwise be masked or overlooked, especially when LV volume overload occurs in breeds predisposed to DCM. The research team considers it very important to publish such cases, as this will help the entire veterinary community quickly accumulate knowledge and experience for diagnostic and treatment of similar and other cases.
Ebstein's anomaly is a rare congenital cardiac abnormality characterized by an abnormal positioning of the cusps of the tricuspid atrioventricular valve. This study aimed to report the clinical and pathological aspects of the condition in an adult medium-sized mixed-breed dog, treated at a veterinary hospital in Brazil, through clinical evaluation, echocardiography, and post-mortem examination. This case highlights the importance of imaging exams for accurate diagnosis and the formulation of therapeutic strategies aimed at patient survival. To our knowledge, this is the first report of this congenital cardiac anomaly in a medium-sized mixed-breed dog.
Wildlife animals in human care can develop pathological processes that rarely occur in their natural habitats, including neoplastic disorders. This report presents the post-mortem pathological findings of a white-tailed deer (Odocoileus virginianus) from a conservation center in Medellín, Colombia. O. virginianus had lung metastases originating from a primary papillary ovarian carcinoma. The post-mortem examination revealed macroscopic and microscopic involvement of multiple organs, including the ovaries, uterus, lungs, kidneys, liver, and spleen. Immunohistochemical analysis showed positive staining for pancytokeratin in neoplastic epithelial cells. This case underscores the importance of recognizing and understanding the multi-causal pathological processes contributing to the death of a wild animal in captivity.
A two-year-old male Siamese cat was submitted for necropsy. The animal had been anorexic, exhibited aggressive behavior, and had collided with objects around the house. Radiographic evaluation revealed an opaque abscess in the thoracic mediastinal region, and the cat died two days later. At necropsy, a slightly irregular abscess was found in the mediastinal region, varying from white to yellow, measuring 6 x 4 cm. The cut section contains yellow, irregular, and poorly defined areas interspersed with discrete red areas of firm consistency, along with hard areas. Histologically, the mediastinal abscess showed proliferation of poorly collagenized fibrous connective tissue, intense angiogenesis, and a marked infiltration of macrophages and epithelioid macrophages surrounding extensive areas of liquefactive necrosis with cellular debris, as well as abundant viable and degenerated neutrophils and areas of mineralized bone matrix formation. Aseptically collected fragments of the mediastinal abscess were submitted for bacterial culture, which isolated Pseudomonas aeruginosa. The anatomopathological and microbiological findings confirmed a diagnosis of mediastinal abscess due to Pseudomonas aeruginosa in a cat. We highlight the importance of both pathological and microbiological evaluation in such cases, expanding the differential diagnoses of mediastinal masses in cats.
An 18-year-old, American Paint mare presented for acute colic for a suspected colon torsion. On presentation, the blood and abdominal lactate were 1.3 mmol/L (normal range 0-2 mmol/L) and 5.3 mmol/L (normal range <2 mmol/L), respectively. In the following morning, her blood and abdominal lactate increased to 7.3 mmol/L and 9.9 mmol/L. Due to uncontrollable pain, lack of a surgical option due to financial limitations, and increasing suspicion for a strangulating lesion, euthanasia was elected.
A 10-month-old dog with a history of vomiting with blood and diarrhea after ingesting plastic bags. An ultrasound examination revealed peritonitis and multiple gastric ulcers. The dog was referred for surgery. During the surgical procedure, extensive ulcers were observed in the stomach mucosa. A gastrectomy of the affected region was performed. The dog didn’t recover from the surgical procedure.
Feedlot with 3,700 animals. About 20 animals died in one month (December 2023). In January 2024, 7 new animals died within 2 days, prompting a visit to the establishment. On physical examination, clinical signs included apathy, lethargy, marked ptyalism and sialorrhea, watery diarrhea, and dyspnea with superficial tachypnea. The affected animals often adopted a kyphotic posture and refused to move when stimulated (Fig.1). Clinical signs began 15 to 45 days after arrival at the feedlot. Treatments with tilmicosin, tylosin, florfenicol, and tulathromycin were administered without a favorable response. The cattle had been fed a low-fiber, high-cereal diet containing monensin.
Ovarian granulosa cell tumor (GCT) is a common type of sex cord neoplasm in cattle. This paper reports a rare case of GCT identified in a bovine abortion. A necropsy was performed on an 8-month-old bovine fetus, revealing an enlarged right ovary measuring 5.5 cm. The cut surface displayed reddish cystic areas with mucinous content, interspersed with whitish to blackish regions. The histopathological evaluation identified a benign epithelial neoplastic proliferation with an acinar arrangement supported by fibrocollagenous stroma. Immunohistochemistry was performed using antibodies against cytokeratin AE1/AE3, vimentin, protein S-100, chromogranin A, inhibin, and somatostatin. The tumor stained positive for cytokeratin AE1/AE3 and vimentin, while protein S-100, inhibin, chromogranin A, and somatostatin were non-reactive. Polymerase chain reaction (PCR) tests for Toxoplasma gondii, Neospora caninum, and bovine viral diarrhea virus yielded negative results. This report provides a detailed anatomical, histopathological, and immunohistochemical characterization of a congenital GCT in a bovine fetus.
Cases of neurologic disease occurred in a sheep farm in late 2023, with a surge in cases in July 2024. The disease affected lambs more frequently. Clinical signs lasted from 7 days to 1 month and included blindness, ataxia, lateral deviation of the head, circling, and reflux of ruminal contents through the nose. One animal had exophthalmos. There were several dogs on the farm. The total number of sheep on the farm was 100 and 50 were in the group where the disease occurred. Six of those 50 had clinical signs and died. All sheep were free in the pasture.
Rhinosporidiosis is a chronic disease caused by Rhinosporidium seeberi, which can infect several host species, including domestic animals and humans. The taxonomy of R. seeberi is still controversial, but scientific evidence supports the classification of this organism as a Mesomycetozoan. Considering the absence of previously reported cases of rhinosporidiosis in the Northern Region of Brazil, the goal of this report was to describe the clinical and pathological findings of a case of R. seeberi infection in a male mule in Araguaína (Tocantins State, Brazil). An 8-year-old male mule presented respiratory difficulties due to a polypoid exophytic lesion that partially obstructed the nasal cavity. The lesion was surgically excised and submitted for microscopic analysis. Microscopically, there was multifocal erosion, epithelial hyperplasia, diffuse inflammatory infiltrate, composed of many histiocytes and plasma cells, and fewer neutrophils and lymphocytes, with numerous intralesional organisms with diameters ranging from 10 to 400 μm compatible with sporangia exhibiting numerous nuclei and endoconidia compatible with R. seeberi.
A 3-year-old, female, Plott hound dog had a history of severe facial pruritus, swelling, and drooling. The week prior, this dog and three other dogs hunted feral hogs. At the time this dog was submitted for necropsy at the Louisiana Animal Disease Diagnostics Laboratory (LSU Diagnostics), the two other dogs had already died.
An 18-year-old English thoroughbred gelding was evaluated because of incoordination, circling, and head pressing. The horse died 5 days after the clinical signs started.
