They are animals that have had changes made to their DNA through molecular techniques. Changes in the DNA give these animals new characteristics.
Transgenic animals are genetically modified animals which have had genes from another species inserted into their DNA. The first GM animals were transgenic mice, created in 1980.
Since this time, further techniques have been developed. As well as inserting genes, it is now possible to ‘knock out’ specific genes, or to make larger-scale genetic alterations. Such animals are now generally referred to as GM animals.