Mammary neoplasms are described as the third most common type of feline tumor, after haematopoietic and skin tumors, and present a challenge for clinicians because the prognosis for feline mammary tumors ranges from guarded to poor. Thus, it is necessary to define new therapeutic approaches and establish more in-depth knowledge about this disease in felines. The main aspects of the diagnosis, prognosis and treatment of feline mammary neoplasia were discussed, aiming to standardize the criteria and to serve as a guide for pathologists and veterinary clinicians.

Objectives This study presents the clinical, pathological, immunohistochemical and molecular characterization of 26 cats with feline chronic gingivostomatitis (FCG). Methods Oral mucosal biopsies, blood and swabs were collected from cats presenting with oral lesions. The tissue sections were submitted for histopathology and immunohistochemical analysis for feline calicivirus (FCV), feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). The swabs were subjected to PCR analysis for FCV, and blood for FeLV and FIV. Results The main clinical findings were dysphagia (88.2%), halitosis (76.5%), sialorrhea (47.1%), weight loss (41.2%), intense oral discomfort (35.3%), oral hemorrhage (17.6%), and lackluster and fragile coat (11.8%). Gross inspection revealed bilateral lesions across the palatoglossal fold to the lateral tongue base. The lesions were diffuse, proliferative, intensely red and friable, and bled easily upon examination in 80.8% of cases. In 23.1% of cases, the lesions were multifocal to coalescent, at times forming multiple vesicles on a reddened, edematous palatoglossal fold. Microscopic examination showed that 15.4% of lesions had moderate (grade 2) and 84.6% had severe (grade 3) inflammation. Immunohistochemistry revealed the presence of FeLV antigens in the epithelium and the inflammatory infiltrate of 30.8% of the cats with FCG. FCV antigens were not detected in the FCG lesions. Conclusions and relevance The FCG cases analyzed could not be correlated with FCV. It is possible that FeLV plays a role as a causal agent of lesions in cases where the presence of the virus has been confirmed by immunohistochemistry in epithelial samples.

Mammary neoplasms are the most frequent tumors in female dogs. Of these neoplasms, benign mixed tumors (BMTs) and carcinomas in mixed tumors (CMTs) represent a large proportion of small animal oncology diagnoses. Together with carcinosarcomas (CSs), these three neoplastic entities are characterized by the proliferation of benign or malignant epithelial, myoepithelial, and mesenchymal cells, depending on their histological types. This histological heterogeneity, in addition to their molecular heterogeneity, confers these tumors with distinct biological behavior, which results in the need for different clinical and therapeutic approaches. The present consensual document elucidates the oncological issues related to the diagnosis, prognosis, and treatment of BMTs, CMTs, and CSs of the canine mammary gland.

Objectives The aim of this study was to report the clinical, radiographic and pathological features of pulmonary Langerhans cell histiocytosis in four cats, and carry out a literature review of feline histiocytic diseases. Methods Necropsy reports archived at the Department of Veterinary Pathology of the Federal University of Rio Grande do Sul were reviewed. The clinical information was then obtained from the clinical records at the Veterinary Hospital. Routine samples had been collected during necropsy, fixed in 10% formalin, routinely processed for histology, and stained with hematoxylin and eosin. Samples of lung were submitted for bacterial and fungal culture. Tissue sections of lung underwent immunohistochemical testing for vimentin, pancytokeratin, CD18, CD3, CD79αcy, E-cadherin and Iba1. Results This disease affected mixed breed cats aged 7–14 years. Clinical signs consisted of severe mixed inspiratory and expiratory restrictive dyspnea, lethargy and anorexia. Thoracic radiographs revealed different lesion profiles, predominantly of an interstitial and alveolar pattern. Grossly, the lungs were diffusely firm and did not collapse. The pleural surface was bright and irregular due to multifocal-to-coalescent, well-demarcated, white, firm nodules that also extended into and obliterated the pulmonary parenchyma. Histological changes were characterized by poorly demarcated infiltration with histiocytic cells arranged in cohesive groups within the alveolar, bronchiolar and bronchial spaces. Histiocytic cells had intense cytoplasmic immunolabeling for vimentin and Iba1, and robust membrane immunolabeling with CD18 and E-cadherin; these cells were negative for CD3, CD79αcy and pancytokeratin in all cases. Conclusions and relevance This article confirms that pulmonary Langerhans cell histiocytosis is a rare disease that occurs in middle-aged to older cats and causes widespread involvement of the pulmonary parenchyma, inducing acute or chronic, progressive respiratory disease characterized by mixed restrictive dyspnea that eventually leads to death. While a definitive clinical diagnosis is challenging, the nodular appearance of the pulmonary changes, together with the histological and immunohistochemistry findings, suffice for diagnostic confirmation of pulmonary Langerhans cell histiocytosis.

Dermatophytosis caused by Microsporum canis is a heterogeneous disease with variable clinical manifestations. M. canis is a zoophilic dermatophyte and the most frequent fungi isolated from dogs, cats and children in Brazil. The aim of this study was to investigate the genetic variability of M. canis isolates from different animal species using two microsatellite markers, namely, McGT(13) and McGT(17), and to correlate the results with the clinical and epidemiological patient data in Brazil. The study included a global set of 102 M. canis strains, including 37 symptomatic cats, 35 asymptomatic cats, 19 human patients with tinea, 9 asymptomatic dogs and 2 symptomatic dogs. A total of 14 genotypes were identified, and 6 large populations were distinguished. There was no correlation between these multilocus genotypes and the clinical and epidemiological data, including the source, symptomatology, clinical picture, breed, age, sex, living conditions and geographic location. These results demonstrate that the use of microsatellite polymorphisms is a reliable method for the differentiation of M. canis strains. However, we were unable to demonstrate a shared clinical and epidemiological pattern among the same genotype samples.

Using a retrospective study, 493 cats tested for FeLV and FIV were selected for analysis of the association between hematologic findings and positivity at immunoassay test. Individual and hematologic variables were assessed considering the influence of results using univariate and multivariate logistic regression analysis. Out 153 of the 493 cats were positive for FeLV (31%), 50 were positive for FIV (10.1%) and 22 were positive for both FIV and FeLV (4.4%). Multivariate analysis detected significant associations between FeLV infection and age below 1 year (p=0.01), age from 1 to 10 years (p=0.03), and crossbreed (p=0.04). Male cats were more likely to be FIV-positive (p=0.002). Regarding hematological changes, FeLV-positive cats have higher odds to anemia, leukopenia and lymphopenia than FeLV-negative cats. FIV-positive cats are more likely to have anemia than negative. Identification of associated factors related to animal status and correlation of hematological disorders with infection by retroviruses in cats could be useful for detecting these retroviral diseases in cats.

Objectives This study aimed to characterize the cytologic, pathologic and immunohistochemical (IHC) aspects of feline giant-cell sarcoma. Methods Biopsy and necropsy reports from the Department of Veterinary Pathology were retrieved, and 13 cases of pleomorphic sarcoma (PS) were selected according to the established epidemiologic, pathologic and IHC criteria. All samples were fixed in 10% formalin, routinely processed for histology, and stained with hematoxylin and eosin. Samples also underwent IHC testing for vimentin, ionized calcium-binding adaptor molecule 1 (Iba-1), desmin, actin and S-100. Results The mean age of the affected cats was 9.5 years, and females were over-represented. Most neoplasms were observed in the flank, lateral thorax, limbs and interscapular region, and were >2 cm in diameter. Cytology analysis revealed highly cellular preparations with three distinct populations (spindle cells, small round cells and multinucleated giant cells) in a dense eosinophilic stroma. Histologically, PS was composed of a combination of these three populations. IHC labeling for vimentin and Iba-1 was strongly positive for spindle cells and multinucleated giant cells, respectively. Desmin/actin showed variable labeling among the samples. S-100 was negative in all samples. Conclusions and relevance PS is a neoplasm of mesenchymal origin, also known as malignant fibrous histiocytoma. The predominant subtype in this study that affected the cats was the giant-cell type, characterized by the presence of multinucleated giant cells among spindle-shaped cells. These findings are similar to those described in human patients; thus, a comparison between the neoplasms seen in these species might be useful, and the knowledge of biologic behavior and overall treatment approach for humans could be extrapolated to cats.

Sarcocystis neurona is the main agent associated with equine protozoal myeloencephalitis (EPM). Apart from horses, S. neurona has been occasionally described causing neurologic disease in several other terrestrial animals as well as mortality in marine mammals. Herein, we describe the clinical, pathological, and molecular findings of a fatal case of S. neurona-associated meningoencephalitis in a domestic cat. The causing agent was analyzed by multilocus genotyping, confirming the presence of S. neurona DNA in the tissue samples of the affected animal. Significant molecular differences were found in relation to S. neurona isolates detected in other regions of the Americas. In addition, the parasite was identical to Sarcocystis sp. identified in opossum sporocysts in Brazil at molecular level, which suggests that transmission of. S. neurona in Brazil might involve variants of the parasite different from those found elsewhere in the Americas. Studies including more samples of S. neurona would be required to test this hypothesis, as well as to assess the impact of this diversity.