Female dogs, especially intact or neutered lately, are at increased risk for reproductive disorders including mammary tumors (MTs). This retrospective study evaluated the prevalence of reproductive pathology and associated mortality in a cohort of female dogs presented at a single veterinary clinic. The medical records of female dogs born in 2000–2003 were reviewed. The study included 599 cases, of which 293 were followed up until death. Causes of death were analyzed according to the spaying status. Among the 599 female dogs, 306 were intact (51%), 50 (8%) had been spayed before 2 years of age (ES, early spaying), and 243 (41%) after 2 years (LS, late spaying). During their lifetime, 79 dogs (13.2%) developed pyometra, and 160 (26.7%) a mammary tumor. Among the 293 dogs with complete follow-up, 103 (35.1%) had at least one MT during their lifetime, of which 53 (51.5%) died of their mammary cancer. Spayed (ES + LS) female dogs had a 4-fold decreased risk of dying from mammary cancer (OR = 0.23, 95% CI 0.11–0.47, p < 0.0001) compared to intact females. In this low-sterilization rate population, MTs developed in 35.1% of female dogs over their lifetime and was the cause of death in half of them.

Very few studies, often with very small cohorts, have proven chemotherapy efficacy against canine aggressive mammary carcinomas, either in terms of metastasis or median survival, in dogs after surgery and chemotherapy, with such outcomes not being confirmed by other studies. As a result, we lack efficient standardized protocols, which exist in human cases, according to the grade and stage of the tumor in dogs. In this case report, we describe a relapsing grade III solid mammary carcinoma evolving into prominent lymphatic intravascular invasion with multifocal nodal extension (stage IV); we applied an intensive treatment combining radical surgery and intensive adjuvant chemotherapy. The latter combined carboplatin maximal-tolerated-dose chemotherapy, with doses adjusted as necessary, and metronomic chemotherapy with firocoxib, toceranib and chloraminophene, progressively administered and carefully monitored. Adapting the doses prevented adverse events and resulted in 218 days of survival with good quality of life. To our knowledge, this is the first description of such a treatment combination. Our result should be confirmed with a large-scale prospective study.

Very few studies, often with very small cohortes, tended to prove chemotherapy efficiency against canine agressive mammary carcinomas, either on the metastasis or on the median survival of dogs after surgery and chemo, and this was not confirmed by other studies. As a result, we lack standardized efficient protocols that exist in human cases according to their grade and stage. In this case report of a relapsing grade III solid mammary carcinoma evolving into prominent lymphatic intravascular invasion with mutifocal nodal extension (stage 4), we applied an intensive treatment combining high dose surgery and intensive adjuvant chemotherapy. This adjuvant chemo combined a carboplatin maximal-tolerated-dose chemotherapy, with doses adjusted as necessary and a metronomic chemotherapy with firocoxib, toceranib and chloraminophen, progressively added together and carefully monitored. Adapting the doses allowed to avoid adverse events and to obtain 237 days of survival with good quality of life. To our knowledge, it is the first description of such a combination of treatment. That result should be confirmed by a prospective large-scale study.