I'm building a dog crate/coffee table for my dad. Is there any finish that would withstand the abuse dogs would do to it? I'm pretty ignorant about finishing, so any help would be appreciated.
There's the table top, and there's the crate. Both will get some abuse, but the type and intensity will vary. Keep in mind that nothing will stand up to chewing. Not even paint.
For the crate, you want something that's tough. Polyurethane would work well. Unfortunately, poly is difficult to repair. On the other hand, a varnish like Waterlox produces a hard finish, which is less resistant to scratches, but it's relatively easy to repair. Shellac is very easy to repair, but hard and somewhat brittle. Since the crate is enclosed, I would not use anything oil-based for the inside, or it will take forever to off-gas.
For the top, scratches from dog claws/ nails are less of a concern. You could go with Behlen's Rock Hard varnish for that. But Waterlox would work well too. Shellac might not be the best choice if there is a high chance of water/ alcohol spillage. A water-bourne finish such as polycrylic is also an option, but you'll probably want to put shellac or boiled linseed oil underneath it for some color.
So, all things considered, I'd put three coats of Minwax polycrylic on the inside of the crate, 4 coats of Waterlox on the outside of the crate, and 5-6 coats of Waterlox for the table top.
But there are lots of other options. What kind of wood are you using?