Most beaver dens are obvious, that big pile of sticks and logs in the water can be seen for a long way and the dams are obvious as well. While there are bank beaver that den in holes along the bank it is easy to find them as well. Why would you want a dog to hunt for them. I don't know of any state where you can take eaver with a gun, just traps. There may be a few but I never heard of them.