My ant problem was indoors. I found a pet safe way to get rid of them.

It's this company that uses peppermint oil to kill them. I had no idea that peppermint could kill ants. I was very happy with their ant spray.

Here's a link to their page. It's supposed to be natural earth/pet friendly products to kill pests.

Safer Brand/Victor Poison Free

As for the dandelions, I think they may have a pet safe weed killer as well.

Good luck!