Abdominal ultrasonographic findings in dogs with mammary tumors: association with tumor characteristics and survival

Abstract

Abdominal ultrasound is frequently performed as part of initial staging of canine mammary tumors. The aims of this study were to describe abdominal ultrasonographic findings present at diagnosis of mammary tumors in dogs and to assess their value for associations with histopathological results and treatment outcome. The medical records of 201 female dogs diagnosed with mammary tumors that had abdominal ultrasonography performed as part of their initial clinical evaluation were reviewed. Histopathological diagnosis of malignant mammary tumors was obtained in most cases (86%; 172 cases). One hundred and fifty-seven animals (78%) had some ultrasonographic abnormality. A total of 338 ultrasonographic changes were identified, and the spleen was the organ with the highest frequency of ultrasonographic changes (20%), followed by the uterus (18%) and the liver (16%). Abdominal ultrasonography abnormalities were not associated with mammary tumor malignancy (OR = 1.7; P = 0.27). Ultrasonographic evidence of enlarged intraabdominal lymph nodes was associated with metastases in surface regional lymph nodes (P < 0.05). Dogs with regional metastasis were more likely to present some abdominal ultrasonographic change (OR = 6.1; P = 0.04). Animals with ultrasonographic evidence of intraabdominal lymph node enlargement presented shorter survival after mastectomy. Abdominal ultrasonographic abnormalities are common in dogs with mammary tumors and are not associated with malignancy. However, the presence of intraabdominal lymph node enlargement identified by ultrasound may be associated with regional metastasis and shorter survival rates.