Needs to be charged frequently

I never charged mine at all

Strange. Another user has posted the same problem. The charge normally lasts for months.

After charging, can you check the charge level in settings, to confirm that it's really fully charged?

Is ATV sleeping (no light) when not in use?

The consensus for the other user was that the remote was bad and should be replaced under warranty.

Read this:

http://help.apple.com/appletv/#/atvb7d4de50d

Unless the dog likes to sleep on the remote and would be pressing the buttons for long periods, the battery in it must be bad. Return it for a replacement under warranty. Batteries are chemical cells and failures early in life are not uncommon. Engineers call it infant mortality. That is why manufacturers offer warranties.