Advances in anti-cancer therapies require a growing understanding of the genetic and phenotypic profile of each cancer. Indeed, the use of anti-cancer immunotherapy requires an understanding not only of the various players in the relationship between the immune system and different tumor types, but also of how they interact. In the future, anti-cancer therapies are likely to be increasingly individualized. This knowledge has led to the development of anti-tumor immunotherapies, both in humans and animals, some of which are clinically proven to be effective. Effectiveness depends on both the vaccine antigen chosen and the mode of antigen administration. These numerous trials give us great hope for the future in finding effective ways of preventing and treating cancers. Finally, given the similarities between human and animal tumours, the use of immunotherapy in pets could serve as a reference for a similar treatment in humans.