Survival in female dogs with mammary neoplasia

Objective. To evaluate selected biological and histological factors associated with the survival of female dogs with mammary neoplasms. Materials and methods. An epidemiological study was performed based on the medical records of 72 female dogs diagnosed with mammary neoplasms. Associations between the characteristics of the female dogs, their reproductive status, the presence of parturition, the post-surgical survival time (m) and the final outcomes of the individual dogs were evaluated. Life tables and a Kaplan-Meier estimator were used for the statistical analysis of survival. Results. The female dogs evaluated were nulliparous (65.28%), with a mean age of 9.53±3.07 years and a weight varying between 1.5 and 49.1 kg (median 10.5 kg). The mortality incidence rate was 0.06 cases/patient/month (50 deaths/827.1 month of follow-up). Of the female dogs with mammary neoplasia, 37.50% survived, 15.28% were euthanized and 30.56% died. The risk of death was 60.5 cases/1,000 female dogs/month and the probability of post-surgical survival in months was 30.36%. Overall post-surgical survival was associated with the age, size and reproductive status of the female dogs; along with size, subtype, malignancy and TNM classification of the tumor (p<0.05). Conclusions. To ensure survival of canine females with mammary neoplasia early diagnosis by thorough physical examination and cytology, surgical removal when necessary, and timely consultation are necessary. Variables that are predictive of survival include the age and reproductive status of the animals, as well as the size of the tumor.