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Feline infectious peritonitis (FIP) is one of the most important infectious diseases and a significant cause of death in cats. While the pathology of FIP has been well documented, there is little information on the hepatic lesions. The aim of this study was to characterize the macroscopic, microscopic and immunohistochemical patterns of the liver lesions in cats with FIP. A retrospective study was conducted on 131 cats with FIP, of which 59 had histological inflammatory lesions in the liver and were immunopositive for feline coronavirus. Four major gross patterns were defined: perihepatitis (21/59); nodular with perihepatitis (18/59); nodular multifocal (13/59); and diffuse (7/59). Four histological patterns were observed: (1) random pyogranulomas; (2) random multifocal to coalescent caseous necrosis surrounded by pyogranulomatous inflammatory infiltrate, fibrin and cellular debris; (3) perihepatitis; and (4) random multifocal to coalescent caseous necrosis surrounded by neutrophils, macrophages, lymphocytes and plasma cells. Most cats had more than one histological pattern. FIP virus antigen was detected in macrophages in the pyogranulomas and around the necrotic areas. The diagnosis of FIP remains challenging, especially in cats without effusion. The liver can be considered a suitable site for biopsy when feasible., Competing Interests: Declaration of competing interests The authors declared no conflicts of interest in relation to the research, authorship or publication of this article., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Feline infectious peritonitis (FIP) is an important cause of death in cats. Thoracic manifestations are less common than abdominal manifestations, and FIP-associated respiratory disease is poorly documented. This study aimed to investigate pathological findings in the respiratory tract of cats with FIP and the occurrence and distribution of feline coronavirus antigen in the respiratory tract using immunohistochemistry. A retrospective study was carried out on 112 cats with FIP, of which 66 had inflammatory histological lesions in the respiratory tract (58.9%) and were included in this study. Three major gross patterns were defined: marked fibrin deposition in the thoracic cavity with lung atelectasis; marked fibrin deposition in the thoracic cavity with lung pyogranulomas; and lung pyogranulomas without thoracic effusion. Histological analysis revealed primary lesions in the visceral pleura and lung parenchyma at a similar frequency, with multifocal to diffuse presentations. Marked lesions were commonly observed. Five major histological patterns were defined: pleuritis; pleuritis and vasculitis/perivascular injury in the lung parenchyma; pleuritis and pneumonia; perivascular injury in the parenchyma without pleuritis; and pneumonia without pleuritis. In the pleura and pulmonary parenchyma, FIP virus antigen was detected in perivascular and peribronchial macrophages and in macrophages within bronchial-associated lymphoid tissue and foci of necrosis and inflammation in the pleura and lung parenchyma. Co-infections with retroviruses were detected in 47 cats (71.2%), mainly with feline leukemia virus (62.2%). Although FIP is a systemic disease, some cats developed significant lesions in the thoracic cavity, including involvement of the upper respiratory tract and presenting respiratory signs, without other classic signs of FIP. This work advances our knowledge of FIP in the respiratory system, helping veterinarians to recognize the various presentations of this disease., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Branchial cysts are a congenital anomaly in humans and other animal species. In this study, twenty commercially bred slaughtered pigs ranging from 120 to 150 days of age, sourced from different farms and lots, were found to have cysts in the oropharyngeal region at meat inspection despite the absence of clinical signs. Two cysts were selected for histopathological examination. The first cyst was surrounded by fibrous connective tissue and lined by a simple single cell layer of epithelium. The second cyst comprised a squamous pseudostratified to simple stratified epithelium, accompanied by a mild inflammatory infiltrate. This cyst was also surrounded by fibrous connective tissue and glands. The pathological diagnosis of branchial cysts in slaughtered pigs was established on the basis of their anatomical location and gross and microscopic findings., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The aim of this study was to characterize the pathological and immunohistochemical aspects of pancreatic carcinoma in cats, through a retrospective study. From January 2010 to December 2021, 1,908 cat necropsies were performed, in which 20 cases of exocrine pancreatic neoplasia were diagnosed (1.04%). Affected cats were mature adults and seniors, except for one 1-year-old cat. In 11 cases the neoplasm was a soft, focal nodule on the left (8/11) or right (3/11) lobe. In nine cases there were multifocal nodules throughout the pancreatic parenchyma. The size of the single masses ranged from 2 to 12 cm, and the multifocal masses from 0.5 to 2 cm. The most frequent tumour type was acinar carcinoma (11/20), followed by ductal carcinoma (8/20), undifferentiated carcinoma (1/20) and carcinosarcoma (1/20). On immunohistochemical evaluation, all the neoplasms were remarkably reactive to pancytokeratin antibody. The ductal carcinomas were strongly reactive for cytokeratins 7 and 20, which proved to be a good marker for pancreatic ductal carcinoma in cats. The main form of metastasis was abdominal carcinomatosis, with a marked invasion of blood and lymphatic vessels by neoplastic cells. Our findings reinforce the fact that pancreatic carcinoma should be rated highly in the differential diagnosis in mature adult and senior cats with abdominal masses, ascites and/or jaundice., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Septicaemia is the main pathological manifestation of Salmonella infection in chinchillas (Chinchilla lanigera), although information on its pathology is limited. We now describe the gross, histological and immunohistochemical features of Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) infection in ranched chinchillas. Eighty-five adult pregnant chinchillas had anorexia, prostration, weight loss, hyperthermia and abortion. Necropsy of 13 animals revealed splenomegaly, hepatomegaly, mesenteric lymphadenomegaly, prominent Peyer's patches, pulmonary oedema, white pinpoint lesions in multiple organs and petechiae in the urinary bladder. In all cases, histological lesions were consistent with septicaemia, characterized by acute necrotizing hepatitis, splenitis, lymphadenitis, cystitis, pneumonia, enterocolitis, gastritis and/or nephritis. Immunohistochemistry for Salmonella spp on seven cases revealed intralesional immunolabelling in all affected organs. Salmonella sp was isolated from liver, spleen, intestinal contents and blood of 10 chinchillas. Isolates of four animals were identified as S. Typhimurium., Competing Interests: Conflict of Interest Statement The authors declared no conflicts of interest with respect to the research, authorship or publication of this manuscript., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Pneumonia in cats may cause severe lung injury and consequent death. We describe the post-mortem findings and aetiologies of naturally fatal pneumonia in 78 domestic cats, using gross and histopathological examinations, immunohistochemistry and microbiological techniques. Morphological patterns found were bronchopneumonia (27/78), interstitial (15/78), bronchointerstitial (13/78), granulomatous (8/78), aspiration (8/78) and pyogranulomatous (5/78) pneumonia, and pleuropneumonia (2/78). Bacterial pneumonia was identified as the most common cause (32/78), followed by viral (15/28 feline calicivirus, 10/28 felid alphaherpesvirus 1 and 3/28 both viruses), aspiration (8/78), fungal (5/78) and parasitic pneumonia (5/78). Co-infection with feline immunodeficiency virus and feline leukaemia virus was found in 54 cats. Viral infections involved cats of all ages, indicating the importance of investigating viral causes in cats with respiratory diseases, including in adult and ageing cats., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Fatal hypothermia represents a diagnostic challenge in veterinary pathology. Wischnewski spots (WS) and black oesophagus (BO) have been described in human cases of fatal hypothermia but rarely in animals. We now describe WS and BO in suspected fatal hypothermia in a free-ranging brown howler monkey (Alouatta guariba clamitans) and a pet rabbit (Oryctolagus cuniculus). Both animals had dark spots resembling WS on the gastric mucosa and the monkey also had BO with haematin deposition. In both cases, stress factors and relatively cold environmental conditions were present prior to death., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Salmonella spp. are gram-negative commensal bacteria of vertebrates, including reptiles. Infected snakes may be asymptomatic or manifest clinical disease and death, especially after stressful events. Salmonellosis was diagnosed in 10 captive snakes from the Bothrops genus. The most frequent changes were emaciation (8/10), fibrinonecrotic or granulomatous hepatitis (8/9), fibrinonecrotic or granulomatous enterocolitis (8/9), necrotic and heterophilic myocarditis (2/10), fibrinonecrotic or granulomatous pancreatitis (2/5), fibrinoheterophilic osteomyelitis (1/10), fibrinous and pyogranulomatous pericarditis (1/10) and granulomatous splenitis (1/6). Salmonella enterica was isolated from six cases. The subspecies identified were arizonae (3/6), diarizonae (1/6) and houtenae (1/6), in addition to the serotype Typhimurium (1/6). In cases without isolation, there was immunolabelling of Salmonella spp. in intestinal (3/4), hepatic (1/4) and cardiac (1/4) lesions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

There are few pathological and immunohistochemical descriptions of thyroid neoplasms in cats. We investigated neoplasms of the thyroid in 31 cats (average age 15.6 years) in Southern Brazil. Most (96.8%) of these cases were classified as follicular adenomas and were predominantly unilateral and multinodular. Histologically, macrofollicular adenomas were the most common type observed. Carcinomas represented 3.2% of the investigated tumours. By immunohistochemical labelling, thyroglobulin was expressed more commonly than paired box gene 8 or thyroid transcription factor 1 in the follicular adenomas. One carcinoma was immunopositive for thyroglobulin, pancytokeratin, chromogranin A and synaptophysin, suggestive of a calcitonin-negative neuroendocrine carcinoma., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

We describe the pathology of gastrointestinal tuberculosis in three cows. Gross lesions were found in the jejunum and ileum in all cases, and were characterized by button-shaped ulcers in the mucosa overlying Peyer's patches and adjacent mucosa. One case had similar changes in the pyloric region of the abomasum. In the affected intestinal segments, marked granulomatous inflammation effaced the lymphoid follicles of Peyer's patches and often extended transmurally. Transmural granulomatous inflammation was also found in the abomasum of one cow. Acid-fast bacilli were identified by the Ziehl-Neelsen method and the lesions were immunolabelled by an anti-Mycobacterium tuberculosis complex antibody. M. tuberculosis var. bovis was isolated in one case. Disseminated tuberculosis and marked lung lesions in all cows suggested that the gastrointestinal lesions were most likely secondary to pulmonary infection., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Osteosarcoma is the most common primary bone neoplasm in dogs and often involves the appendicular skeleton. We report the clinicopathological and prognostic features of appendicular osteosarcomas diagnosed in 153 dogs from 2008 to 2018. The survival data for 22 dogs that underwent surgery and chemotherapy were statistically compared with the clinical, histopathological and immunohistochemical data for correlation with prognosis. The affected dogs had a mean age of 9.1 years and a mean body weight of 33.4 kg. No sex predilection was detected, although the incidence was slightly higher in females (52%). Large mixed and purebred dogs were most commonly affected. Long bones were affected in 124 cases (92.5%; 124/134). The extremities affected within long bones were the metaphysis of the proximal humerus (29%), distal radius (17.7%), distal femur (15.3%) and proximal tibia (7.2%). Histologically, osteoblastic osteosarcoma was most commonly detected (56.9%), followed by chondroblastic (13.7%), telangiectatic (11.8%), fibroblastic (7.8%), giant cell-rich (5.2%) and poorly differentiated neoplasms (4.6%). Regional lymph nodes were available for analysis in 28 out of 70 excisional biopsies from amputated entire limbs. Metastases to regional lymph nodes were observed in 14.3% (4/28) of these cases. Distant metastases were found in 75% (39/52) of cases in which diagnostic imaging or necropsy was carried out. The lungs were the most common site of metastasis (87.2%; 34/39 cases). Weight, age, sex, affected limb or bone, histological classification, mitotic count or histological grade did not influence survival (P >0.05). Neoplasms located at proximal extremities (n = 7) of affected limbs had a tendency for a poorer prognosis than those at distal extremities (n = 15) (P = 0.06). For these cases, the 1-year survival rate was 14.3% compared with 40% for neoplasms at distal extremities. There was no significant difference in the survival rate when amputation (n = 16) or limb preservation (n = 6) techniques were employed with chemotherapy (P = 0.20). The survival period of dogs that had undergone limb amputation, or limb preservation surgery, and chemotherapy was 73-1,185 days, with a mean and median of 376 and 256 days, respectively. Mild to marked cytoplasmic immunolabelling of osteopontin was found in all cases but the intensity (P = 0.66) and percentage of neoplastic cells labelled (P = 0.49) did not influence survival., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

We describe a case of penile tuberculosis in a bull. The prepuce was thickened, firm and pale with multifocal to coalescent caseous nodules, and the inguinal and mesenteric lymph nodes were moderately enlarged. Lesions in the prepuce, penis and lymph nodes were characterized by multifocal to coalescent areas of caseous necrosis and marked granulomatous inflammation. Acid-fast bacilli were seen within necrotic foci and Langhans giant cells. Mycobacteriumtuberculosis var. bovis was identified in inguinal lymph nodes by the polymerase chain reaction technique and by bacterial isolation. Although rare, tuberculosis should be considered in the differential diagnosis of granulomatous lesions in the genital tract of bulls., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Chromobacterium violaceum is an opportunistic pathogen of mammals that produces characteristic violet pigment in bacterial culture. We report pneumonia and septicaemia caused by C. violaceum in a horse. Necropsy examination was performed on a 3-year-old Quarter Horse stallion with a history of recurrent episodes of pneumonia, fever, dyspnoea and sanguineous nasal discharge. The lungs were not collapsed, but they contained dark red foci mixed with white areas, and multiple nodules of firm consistency. Within the liver and kidney there were randomly distributed, multifocal, white pinpoint lesions (0.1-0.5 cm diameter) in the capsule and extending into the parenchyma. The brain and spinal cord contained numerous petechiae. Microscopically, the lung had severe multifocal to coalescing infiltration of degenerate neutrophils within the alveoli and parenchyma associated with extensive areas of necrosis and haemorrhage. Rod-shaped bacteria were often present in the centre of the lesions. There was intense intra-alveolar exudation of fibrin and fibrinoid degeneration of blood vessels associated with thrombosis and ischaemic necrosis adjacent to areas of severe haemorrhage. Similar lesions were present in the liver and kidneys. A pure culture of C. violaceum was obtained from samples of the lung and liver. The identity of the organism was confirmed by amplifying and sequencing the 16S rRNA gene with subsequent analysis of sequence similarity., (Copyright © 2017 Elsevier Ltd. All rights reserved.)