On May 17, 2019 the 2^nd Comparative Oncology Mast Cell Meeting took place in Vienna at the old General Hospital campus of Vienna. The event entitled “Classification and Management of Mast Cell Neoplasm in Dogs and Humans: A Comparative Oncology Approach” focused on improvement of therapy in both humans and dogs.

The scientific organization team included experts from human and canine oncology research, namely Emir Hadzijusufovic, Michael Willmann and Peter Valent. The closed session on May 18, 2019 took place in Hotel Regina in the 9^th district of Vienna and served as a working conference with access to faculty members only. The program on day 1 opened with a session about general data on Mast Cells in Health and Disease. During the rest of the day, experts presented their data on molecular markers, grading systems and treatment strategies in MC neoplasms. In the working conference on day 2, experts from the US and Europe came together to discuss diagnosis, classification, prognostication and management of mast cell tumor in dogs and further to compare management strategies and diagnostic algorithms in the canine and human system. Moreover, the aim of the meeting was to develop consensus criteria for improving the treatment of mast cell tumors in dogs. Social Events, such as welcome reception or faculty dinners accompanied the Comparative Oncology Mast Cell Meeting.