Lilypad Arduino used for dog collar

So I’m attempting to put together a lilypad arduino as a dog collar for a class. I am interested in using it to measure heart rate, but haven’t been able to find a system that would be compatible with the project I’m doing (most use photodiodes and making a puppy sit still to do that is ineffective). I was hoping someone may be able to provide guidance on the best approach. It’s mainly the coding I think I would need help with, but I’d love some creative input on the possibilities of the lilypad device.

Thanks!

Hi, Alexis,

best way to do this would be intravenous I think.