Epsilon Archive for Student Projects

Abstract

Mammary gland tumours (MGT) are the most common neoplasia in female dogs, and up to 50% of them are malignant. Treating MGTs is typically conducted through surgery, but there is no consensus on which type of operation yields the best results while also being minimally invasive. Thus, surgical technique, as well as factors such as age at diagnosis, tumour size, lymph node involvement, etc., are important to consider in prognostication and clinical decision-making. This retrospective study aims to investigate the association between different host and tumour factors in dogs diagnosed with MGTs at the SLU University Small Animal Hospital and time to recurrence and overall survival during the years 2017-2019. A total of 264 medical records were reviewed, and dogs that underwent surgery were recruited (n=183) for data collection. Factors that were reviewed include age at diagnosis, breed, dog size, spaying status, size of the largest nodule, number of nodules, number of mammary glands involved, signs of lymph node involvement, signs of radiological metastasis, ulceration, invasion of adjacent tissue, blood sample alterations, surgical technique, tumour character, and subtype. Statistical analyses were performed to assess the factors' correlation to the recurrence of MGTs and death. Mean survival time was estimated for several variables, and dog size (P=0.036), spaying status (P=0.006), lymph node involvement (P=0.004), size of the largest nodule (P=0.013) and tumour subtype (P=0.044) were identified as independent predictors affecting overall survival. In conclusion, the results aligned with previous published reports regarding prognostic markers for MGTs, such as tumour size, lymph node involvement and subtype. It also found spayed dogs to have a 3.7 higher risk of dying then intact dogs. Thus, the study successfully identified some prognostic factors and can act as a model for the Swedish dog population and give some indications for clinical decision making and prognosis discussion.