I agree with the above poster... A .38 or a .357 is plenty for protection against dogs ..We're not talking determined attackers like grizzly bears here.. Most dogs are going to turn tail from just the SOUND of a gunshot..
The lighter weight of the .38/357 is an advantage... You are going to carry the thing a lot and chances of having to use it are slim.. I think that weighing yourself down with a heavier handgun is uneccessary...Get a decent 4" .38 or a light combat magnum in .357...