Eletrocardiografia computadorizada em cadelas com tumores mamários / Electrocardiography in bitches with mammary tumors

The incidence of cancer has increased due to greater longevity of the animals as a consequence of better control of other diseases, improvement of nutrition and good practices in preventive medicine. Malignant tumors can cause paraneoplastic syndrome such as hypercalcemia, anemia, cachexia, among others and consequent cardiovascular disorders. The electrocardiography (ECG) is a complementary exam that can reveal with its traces these rhythmic disorders. Based on that, the objective of this study was to evaluate the ECG in bitches with mammary tumors in order to detect in which type of tumor would be found significant changes as in cardiac rhythm, ECG waves, segments or cardiac axis. Twenty-nine female dogs were used in this study, being 19 bitches with mammary tumor, and they were allocated in three groups: G1: control group (n = 10), G2: benign neoplasia group (n = 6) and G3: malignant neoplasia group (n = 13). The most prevalent type of neoplasia in G2 was the benign mixed tumor (83%), followed by adenoma (17%) whereas in G3: carcinoma in mixed tumor (61%); papillary carcinoma (23%). Regarding cardiac rhythm, it was found sinus arrhythmia (SA) and normal sinus rhythm (NS): G1: 50% SA and 50% NS; G2: 67% SA and 33% NS; G3: 54% SA and 46% NS. No ventricular or atrial arrhythmias were detected. For other parameters in G1, G2 and G3, respectively (mean ± Std error): FC (bpm): 110±9.2, 120 ± 8.5, 124±7,5; P (ms): 48 ± 1.6, 51 ± 1.8, 50 ± 1.2; P (mV) 0.19 ± 0.02, 0.2 ± 0.02, 0.19 ± 0.02; PR (ms): 94 ± 4.3, 93 ± 5.5, 89 ± 3.9; QRS (ms): 56 ± 1.54, 60 ± 4, 62 ± 1.2; R (mV): 1.1 ± 0.06, 1.2 ± 0.24, 0.9 ± 0.13; QT (ms): 203 ± 9.4; 204 ± 7.9; 182 ± 15.6; and cardiac axis (°): 66 ± 6.2, 61 ± 7.9, 70 ± 7.5. There were no significant differences for all cardiac parameters and also for ST interval and T wave morphology. All electrocardiographic parameters found are in accordance with other studies carried out in the canine species. The results regarding tumor types differ from what was found in another study, in which in 18 bitches with mammary tumors, 55% were benign, with prevalence of adenomas (38%) followed by benign mixed tumors, and 45% malignant, with adenocarcinoma prevailing (22%). In another study, it was verified in 63 bitches the predominance of tubular carcinoma (26.56%) and carcinoma in mixed tumors (23.44%). Diverging from the electrocardiographic parameters of this study, a significant difference was found in the R wave amplitude value in the research by Barros et al., (2015) who performed computerized electrocardiography in 50 dogs, not only with mammary neoplasms (55% mammary carcinomas), but also in mastocytomas, lymphomas, benign tumors and other sarcomas. This author found out that the R wave amplitude values of the neoplasia group were lower when compared to the control group. In addition, we suspect that other types of tumors could result in more paraneoplastic syndrome than the mammary neoplasms found in this research. Neoplasms as lymphomas (T cells), apocrine gland anal sac adenocarcinomas, multiple myelomas and thymomas are known as a cause of hypercalcemia of malignancy and histiocytic sarcomas, myelomas, leukemia and lymphomas causing anemia. In conclusion, ECG has no changes in benign or malignant mammary tumors in dogs. However, this fact does not exclude the importance of its performance in pre-anesthetic evaluations. Further studies with a larger sample including the clinical staging of these bitches with a balanced number of animals with low and high staging are suggested.(AU)

Linfonodo axilar como sentinela de neoplasia mamária em cadelas / Axillary lymph node as sentinel for mammary neoplasia in bitches

Linfonodo axilar como sentinela de neoplasia mamária em cadelas. O estudo dos tumores de mama em cadelas é de grande importância devido à alta frequência com que surgem na clínica de pequenos animais. O presente estudo teve como objetivo avaliar a importância do linfonodo axilar como sentinela em neoplasias mamárias de cadelas. Foram avaliadas 49 fêmeas com neoplasia mamária, submetidas à mastectomia unilateral total, utilizando o corante azul patente para a identificação do linfonodo axilar, o qual foi submetido à análise histopatológica com a coloração de hematoxilina-eosina e imuno-histoquímica (IHQ) com anticorpo citoqueratina (AE1/AE3) para procura de metástase. Oito cadelas apresentaram metástases em linfonodo axilar, sendo sete detectadas por histopatologia e por IHQ e uma somente pela IHQ (micrometástase). Uma paciente que apresentava tumor em mamas abdominal caudal e inguinal tinha metástase no linfonodo axilar e inguinal. Assim, observa-se que o tumor pode causar alteração na drenagem linfática provocando metástase em linfonodos que normalmente não drenam determinadas mamas, por isso a retirada do linfonodo axilar deve ser incluída como técnica de rotina para permitir melhor estadiamento das neoplasias mamárias de cadelas.(AU)

Mammary tumors research in bitches is important due to their high incidence. The aim of this study was to evaluate the importance of the axillary lymph node as a sentinel lymph node for mammary neoplasms in female dogs. Forty-nine bitches with mammary neoplasia were submitted to total unilateral mastectomy, and the axillary lymph node was identified using the patent blue dye. This lymph node was processed routinely for histopathological analysis and stained with hematoxylin-eosin and by immunohistochemistry (IHC) with cytokeratin antibody (AE1/AE3) to search for metastasis. Eight dogs had axillary lymph node metastases, seven of which were detected by histopathology and by IHC and only one by IHC (micrometastasis). One dog who presented tumor in caudal and inguinal abdominal mammary glands had metastases in the axillary and inguinal lymph nodes. It is concluded that the mammary tumor can cause alteration in lymphatic drainage leading to metastases in lymph nodes which normally do not drain certain glands; so the removal of the axillary lymph node should be included as a routine technique to allow better staging of mammary neoplasms of bitches.(AU)