The best surgical technique for the treatment of mammary tumors in female dogs has been exhaustively debated among the scientific community. Despite biological knowledge of these tumors, some authors have suggested aggressive procedures, without any clinical advantage. The aim of this study was to evaluate the influence of surgical procedure on the overall survival, disease-free interval and new lesion development interval in dogs with mammary tumors treated according to established prognostic factors. This prospective study included 143 intact female dogs that underwent surgery for mammary neoplasms and were followed up for about 738.5 days. Each animal represented a repetition. Each surgical technique represented a group: lumpectomy (P1), mammectomy (P2), regional mastectomy without cranial abdominal gland involvement (P3), regional mastectomy with cranial abdominal gland involvement (P4), and radical mastectomy (P5). Considering only the first surgical event, 84.6% of animals had more than one mammary tumor, and tumors were identified in two mammary chains in 52.5%. There was no difference in ipsilateral and contralateral tumor development when surgical techniques were compared. Only 33 dogs developed new lesions in remaining mammary tissue, without correlation with primary lesion. Surgical technique had no effect on the overall survival, diseasefree interval and new lesion development interval in patients on this study, which respected oncological surgery principles and established prognostic factors for mammary gland tumors in dogs.

A imuno-histoquímica pode ser aplicada na oncologia veterinária para a definição do imunofenótipo neoplásico, com possibilidades ilimitadas de utilização. A técnica baseia-se na identificação de antígenos "in situ", que podem apresentar valor prognóstico e terapêutico. A expressão de receptores de estrógeno e progesterona está diretamente relacionada ao melhor prognóstico para os neoplasmas mamários, enquanto a super-expressão do receptor KIT (CD117), proteínas Ki-67 (MIB-1), VEGF, CD31 e COX-2 podem ser associados à progressão tumoral para vários tipos histológicos. Essa associação possui valor preditivo em potencial, tendo em vista a possibilidade da utilização de bloqueadores específicos. Esta revisão tem como objetivo apresentar as possibilidades da utilização da imuno-histoquímica nos tumores de cães, visando à definição mais precisa do prognóstico e a indicação de tratamentos específicos para cada paciente.

Mast cell tumors (MCTs) are hematopoietic neoplasms composed of mast cells. It is highly common in dogs and is extremely important in the veterinary oncology field. It represents the third most common tumor subtype, and is the most common malignant skin tumor in dogs, corresponding to 11% of skin cancer cases. The objective of this critical review was to present the report of the 2nd Consensus meeting on the Diagnosis, Prognosis, and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors, which was organized by the Brazilian Association of Veterinary Oncology (ABROVET) in August 2021. The most recent information on cutaneous and subcutaneous mast cell tumors in dogs is presented and discussed.

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Background: Thymomas are epithelial neoplasms of the thymus, although lymphocyte infiltration is common. Histological features are not sufficient to define its biological behaviour, which is dependent of clinical criteria of invasiveness and resectability. Myasthenia gravis may happen as a paraneoplastic syndrome in up to 47% of canine thymomas. Thisarticle aims at reporting a case of thymoma associated with myasthenia gravis in a dog, emphasizing the morphological, phenotypical and therapeutical aspects.Case: A 7-year-old, male Labrador, was presented with a history of acute dyspnea and exercise intolerance. The physical examination revealed a “red-brick” mucousa, tachycardia and cardiac and pulmonar hypofonese. Chest radiographs revealed an area of increased radiopacity in the cranial mediastinum without a plane of separation to the heart. The eccodopplercardiogram exam identified a poorly delimited mass adjacent to the base of the heart, measuring 9.5x6.8cm. Computed tomographydemonstrated it as an expansive neoformation (9.5x6.5x7.8cm). Mass was removed through intercostal thoracotomy and the removed tissue was submitted to histopathology with a diagnosis compatible with type AB thymoma (mixed). Immunohistochemistry was positive for AE1/AE3 citokeratin in 90% of epithelial cells, confirming tumour origin. Tumour infiltrating lymphocytes were positive for CD79a (70%) and CD3 (20%). The proliferation index (Ki-67 imunolabeling) was 60%. About 45 days after surgery the patient was presented with generalized muscle weakness and regurgitation, with confirmed megaesophagus on chest X-ray. Treatment with pyridostigmine was initiated because of suspected myasthenia gravis, and complete remission of the neurological signs occurred within a month. A chemotherapeutic protocol with carboplatin wasthen instituted. After four sessions, a new thoracic radiograph revealed tumour recurrence in the cranial mediastinum. Therefore, metronomic chemotherapy was started sequentially with oral chlorambucil and firocoxib. Patient remained well for nine months when regurgitation and muscle weakness re-initiated, even with pyridostigmine treatment. New chestX-ray demonstrated increased tumour mass and the owner decided for euthanasia, resulting in a survival time of 368 days.Discussion: The prognosis of the thymoma depends on the histological type, clinical staging and presence of paraneoplastic syndromes. Due to the heterogeneity of the cases, there are not enough studies available to compare the animals submitted to different therapeutic modalities. In humans, when possible, and in the absence of metastases, complete surgical resection is the standard treatment followed by chemotherapy and/or adjuvant radiotherapy. In dogs, surgical resection of thymomasshould be considered, despite the invasiveness detected in imaging studies. The presence of paraneoplastic syndromes, such as myasthenia gravis, are commonly associated with worse prognosis, however, as evidenced in this case, pyridostigmine was useful in maintaining the neuromuscular function and patient´s quality of life, along with surgery and adjuvant chemotherapy, which probably contributed to the increase of the expectation of life. Further studies are necessary to evaluate the efficacy of adjuvant chemotherapy in maximum tolerated and metronomic dosage, for thymic neoplasms in dogs.Keywords: thymus, neoplasia, paraneoplastic syndrome, carboplatin, cyclophosphamide.

Background: Breast tumours represent about 50 to 70% of all neoplasms in female dogs and their occurrence is directly related to the reproductive status and patient´s age. The purpose of this research was to apply the Brazilian consensus on diagnosis, prognosis and treatment of canine mammary tumours and to and define the regional epidemiological aspects of canine mammary gland tumours in Vitoria metropolitan region (ES, Brazil) between 2012 and 2016 and to correlate the macroscopic characteristics such as lesion size and location of the neoplasm with histopathological diagnosis, tumours grade and lymph node metastasis.Materials, Methods & Results: Data were collected from the archives of the Laboratory of Animal Pathology of UVV and the clinical files of the patients seen in the Veterinary Hospital Prof. Ricardo Alexandre Hippler in 5 years (2012 to 2016). The animals were separated into groups by age to facilitate classification in the group with the highest occurrence of neoplasms. The evaluation of the macroscopic characteristics was performed through the histopathological record described in the pathology laboratory, for each patient, at the time of the initial evaluation. After descriptive analysis, data was correlated using Spearmann test, and frequency dispersion was evaluated using chi-square test, both in the software Graph Pad Prism v. 6.01. This study included 255 bitches and diagnosis of 486 lesions, once 48.6% of the dogs had more than one lesion. 86.8% of lesions were consistent with actual mammary neoplasms, of which 67% were malignant and 20% were benign. Non-neoplastic lesions corresponded to 7.2% of cases and 5.8% were extra-mammary neoplasms, with an increased incidence of lipomas (39.3%) and mast cell tumours (32.1%). Cross-breed dogs represented 26.7% of cases. Poodles (25.5%), Pinschers (9.8%) and Dachshund (4.7%) were overrepresented. Among mammary glands, the most affected with 30.8% and 25.4% were for inguinal and caudal abdominal mammary gland, respectively.Regarding the histopathological grade, 43.7% of the malignant mammary gland tumours were grade I, 40% grade II and 16.2% grade III. The neoplasms smaller than 3 cm in diameter, corresponded to 43.7% malignant neoplasms, of which 75 corresponded to grade I. Those larger or equal to 3-5 cm in diameter corresponded to 22.1% malignant neoplasm, of which 31 corresponded to grade II, and those larger than 5 cm in diameter corresponded to 25.8% malignant neoplasms, of which 34 corresponded to grade II. Macroscopic ulceration was reported in 35/486 neoplasms; of these, 85.7% were malignant. Necrosis was evidenced, microscopically in 11.7% of malignant neoplasms and there was a weak, positive correlation between the occurrence of necrosis and ulceration (P < 0.0001; rs = 0.223), which also correlated with tumour size and histological grade. Of these patients, 24.4% had metastases, and of these, 8.8% presented macroscopic abnormalities in the lymph node. Discussion:Older dogs are at higher risk of developing malignant mammary gland tumour when compared to young bitches, most neoplasms with a histopathological grade III occurred in animals older than 10 years, in agreement with the literature. Age increasing might be related to more biologically aggressive mammary gland tumours. Early neutering is commonly recommended to prevent proliferative abnormalities in the mammary glands, but it has been related to several disorders, and neoplasms, in some breeds. Multiple tumours in more than one mammary gland with different histopathological diagnoses among them, isn’t related to multicentric disease or worse prognosis, as also seen in this survey.Among mammary glands, the inguinal and caudal abdominal are often the most affected,as it was observed in this study; however, no differences were observed in the occurrence of malignant neoplasms, benign or non-neoplastic. Background: Breast tumours represent about 50 to 70% of all neoplasms in female dogs and their occurrence is directly related to the reproductive status and patient´s age. The purpose of this research was to apply the Brazilian consensus on diagnosis, prognosis and treatment of canine mammary tumours and to and define the regional epidemiological aspects of canine mammary gland tumours in Vitoria metropolitan region (ES, Brazil) between 2012 and 2016 and to correlate the macroscopic characteristics such as lesion size and location of the neoplasm with histopathological diagnosis, tumours grade and lymph node metastasis.Materials, Methods & Results: Data were collected from the archives of the Laboratory of Animal Pathology of UVV and the clinical files of the patients seen in the Veterinary Hospital Prof. Ricardo Alexandre Hippler in 5 years (2012 to 2016). The animals were separated into groups by age to facilitate classification in the group with the highest occurrence of neoplasms. The evaluation of the macroscopic characteristics was performed through the histopathological record described in the pathology laboratory, for each patient, at the time of the initial evaluation. After descriptive analysis, data was correlated using Spearmann test, and frequency dispersion was evaluated using chi-square test, both in the software Graph Pad Prism v. 6.01. This study included 255 bitches and diagnosis of 486 lesions, once 48.6% of the dogs had more than one lesion. 86.8% of lesions were consistent with actual mammary neoplasms, of which 67% were malignant and 20% were benign. Non-neoplastic lesions corresponded to 7.2% of cases and 5.8% were extra-mammary neoplasms, with an increased incidence of lipomas (39.3%) and mast cell tumours (32.1%). Cross-breed dogs represented 26.7% of cases. Poodles (25.5%), Pinschers (9.8%) and Dachshund (4.7%) were overrepresented. Among mammary glands, the most affected with 30.8% and 25.4% were for inguinal and caudal abdominal mammary gland, respectively.Regarding the histopathological grade, 43.7% of the malignant mammary gland tumours were grade I, 40% grade II and 16.2% grade III. The neoplasms smaller than 3 cm in diameter, corresponded to 43.7% malignant neoplasms, of which 75 corresponded to grade I. Those larger or equal to 3-5 cm in diameter corresponded to 22.1% malignant neoplasm, of which 31 corresponded to grade II, and those larger than 5 cm in diameter corresponded to 25.8% malignant neoplasms, of which 34 corresponded to grade II. Macroscopic ulceration was reported in 35/486 neoplasms; of these, 85.7% were malignant. Necrosis was evidenced, microscopically in 11.7% of malignant neoplasms and there was a weak, positive correlation between the occurrence of necrosis and ulceration (P < 0.0001; rs = 0.223), which also correlated with tumour size and histological grade. Of these patients, 24.4% had metastases, and of these, 8.8% presented macroscopic abnormalities in the lymph node. Discussion:Older dogs are at higher risk of developing malignant mammary gland tumour when compared to young bitches, most neoplasms with a histopathological grade III occurred in animals older than 10 years, in agreement with the literature. Age increasing might be related to more biologically aggressive mammary gland tumours. Early neutering is commonly recommended to prevent proliferative abnormalities in the mammary glands, but it has been related to several disorders, and neoplasms, in some breeds. Multiple tumours in more than one mammary gland with different histopathological diagnoses among them, isn’t related to multicentric disease or worse prognosis, as also seen in this survey.Among mammary glands, the inguinal and caudal abdominal are often the most affected,as it was observed in this study; however, no differences were observed in the occurrence of malignant neoplasms, benign or non-neoplastic.

Background: Malignant myoepithelioma is a rare neoplasm in humans and rats, poorly reported in dogs and not previously described in rabbits. This study aims to report a case of malignant mammary myoepithelioma in a domestic rabbit (Oryctolagus cuniculus). Case: A domestic, hybrid, female, entire, nulliparous, 7-year-old rabbit was attended in the Veterinary Hospital Prof. Ricardo Alexandre Hippler at Universidade Vila Velha (UVV) with a history of apathy, lethargy and anorexia. In the clinical examination a 5 cm tumour was observed in the right abdominal mammary gland (M2), along with floating smaller lesions in M1 and M3. There were no palpable abnormalities in the axillary and inguinal lymph nodes. Complete blood count and serum biochemistry were within the normal range. Fine needle aspiration was performed for cytological evaluation of the tumour in M2 and it was suggestive of a malignant glandular neoplasm, with probable epithelial origin. Complete staging included chest and abdominal radiographs, but they were unremarkable. The patient was submitted to a right unilateral mastectomy, involving resection of the inguinal lymph node. The sample was sent to the Laboratory of Animal Pathology of UVV for routine histological evaluation. M2 lesion was compatible with malignant myoepithelioma based on the literature, while nodules in M1 and M3 were classified as mammary cysts. The inguinal lymph node showed no significant abnormalities. An immunohistochemical panel was performed in the Laboratory of Comparative Pathology of the Institute of Biological Sciences at the Universidade Federal de Minas Gerais (UFMG), using immunomarkers (pan-cytokeratin, p63 and vimentin) to characterize the tumour and confirm its diagnosis. Immunohistochemistry revealed expression of p63, and was negative for pan-cytokeratin and vimentin, which confirmed the myoepithelial origin, without involvement of the epithelial compartment. Clinical follow-up was recommended every 2-3 months, including abdominal ultrasonography, chest radiographs, complete blood count and serum biochemistry. Ultrasonography showed thinning of the uterine wall, dilation of 3.7 cm in diameter and presence of endometrial cysts of varied sizes, around 0.7 cm. Neutering was recommended but it was not elected by the pet's responsible. These findings remained stable throughout the follow-up, which was greater than 405 days. Discussion: This is the first report of a malignant myoepithelioma in rabbit, with a detailed description of the clinical, surgical, pathological and immunophenotypic aspects of this neoplasm in this species. This is a tumour characterized by proliferation of epithelioid to spindle-like myoepithelial cells, as observed in this case, forming an extensive and well delimited solid area with marked central necrosis, compatible with what has already been described in the literature in bitches and women. As observed in this case, the neoplastic cells usually exhibit moderate cellular and nuclear pleomorphism, moderate anisocytosis and anisokaryosis, and sever...

Mammary gland tumors represent 42% of all tumors in the bitch. Although there are numerous studies about disease development and progression, some questions remain concerning the surgical treatment. Many surgical techniques may be used for the treatment of canine mammary tumors similar to Medicine, the advantages and disadvantages of each procedure have been extensively discussed. The purpose of this study is to evaluate the influence of surgical procedure on survival, disease free interval and new lesion development interval in dogs with mammary tumors treated according to the biological behavior of these lesions. For this, 143 intact bitches were submitted to surgery for the treatment of mammary tumors between 2007 and 2011. Removal of mammary tumors was performed through the simplest and less invasive surgical procedure necessary for the complete removal of all tumors and main known lymphatic connections between affected glands: lumpectomy, mammectomy, regional mastectomy (including abdominal cranial mammary gland or not) or radical mastectomy. Mean clinical follow-up was 738.5 days. Considering only the first surgical event, 84.6% of animals had more than one mammary tumor, and 52.5% had tumors in both mammary chains. Comparing surgical techniques, there was no difference in ipsilateral and contralateral tumor development. Only 33 dogs developed new lesions in remaining mammary tissue, without correlation with primary lesion. Surgical technique had no effect on overall survival, disease-free interval and new lesion development interval in patients on this study, treated according to oncological surgery principles and established prognostic factors for mammary gland tumors in dogs. It is important to consider these results when deciding on the surgical management of dogs with mammary tumors, to avoid aggressive surgical procedures that will not translate into clinical advantages to the patient.