My nickles worth...
I have a family member that has a large ranch and has problems with feral dogs on a continuing basis. They pack up and attack calves. They can run upwards of 70+ pounds at times, and the ranges are L-O-N-G.
I started with a 22-250, but it ran out of steam and was not reliable past 400/500. I went to a 6mm Rem, and it gave me more reach to about 600-ish.
Then I went to a 300 Win mag in a 40 XB with 178 V-Maxs at 2950.
Worked well at longer ranges and I regularly took dogs to 8090-ish, but I was worried about the bullets tagging an expensive breeding bull, cuz they did not "blow up fast" the way the Hornady rep said they would.
I just picked up a Remington Sendero-II in .264 Win Mag.
I went to this because of the following - there is a 95gr V-Max available for the 6.5 bore size, and the the heaviest varmint bullet in .25 bore is a lighter 75 gr.
The .264 with the 95 V-Max is the flattest shooting rig (using fragile bullets) that is available in a standard case.
While the thought of an exotic wildcat like the 6mm bullet on a .264 case sounds like fun, I'm not sure that's a practical way to go, just for feral dogs...
... of course, one could argue that buying a Sendero-II just for feral dogs doesn't make sense either, but I never met an excuse to buy a rifle that I didn't surender to /ubbthreads/images/graemlins/wink.gif