Regenerative medicine using stem cells has a good safety profile in dogs, cats and horses, i.e. they generally do not cause any deleterious effects on these animals. ^{25, 26, 27, A} A Transient local inflammation may occur in rare cases following intra-articular injection, sometimes referred to as "flare" in horses. ^{8, 10, 28, A} If the animal has an active tumour, it is contraindicated to inject stem cells on the basis of the precautionary principle. Indeed, stem cells modulate the immune system and contribute to the formation of new blood vessels, so they could theoretically promote pre-existing tumor cells. Finally, there is a thrombotic and embolic risk mainly in case of intravascular injection. ^{8, A}