Not sure whether to encourage this behaviour or not

[KimmyF]

My DS often pretends to be a puppy, he will bark, and pant with his tongue out, i just see it as him enjoying using his imagination. Don't stress your DS sounds adorable and very imaginative and as OP have said just stop it when you think it is getting out of hand or inappropriate

[Nai]

I have a 2yo who becomes a pussycat called "Emily" - I think it's normal. It doesn't help that her sister encourages her!!

[Santosha]

Yup. I have another puppy here. Got to the far end of a huge park on wet grass the other day and she decided that she was going to be 'puppy' and crawl all the way back. She was SOAKED and filthy but would not turn back into a girl in spite of all my attempts at persuasion! Part-cute, part-exhausting, all normal!