What was the first GMO animal?

Could you please enlighten me on a matter of biotechnology? Could you explain what the very first genetically modified organism, or GMO, animal was? It would be intriguing to learn about this significant milestone in the realm of scientific advancement. I'm curious about the species involved, the purpose behind its creation, and the impact it might have had on the scientific community and the broader public. Could you also discuss any ethical considerations that might have arisen from this development? I'm eager to gain a deeper understanding of this fascinating topic.