My dogs leave most of the outside critters alone; I've rescued several tarantulas in the house and returned them to the outdoors where they will thrive.

There are toads that live in the yard and garden that use one of the dog water pans as a spa on hot nights and the dogs ignore them (I think they all have been in contact and know that toads taste bad).

They do go after squirrels, and even just standing near the back door and SAYING the word "squirrel" will send the two girls pelting out through the dog door to see if there is one near enough to catch or pester. Cookie has killed two and made contact with two others (that I've seen.)