Typically US vehicle insurance policies cover travel in Canada, but do double-check with your insurance agent. You don't need any additional insurance card for Canada anymore, or so they say; there used to be a special Canada card/form that you'd get from your insurance company. If they'll give you a "Canadian insurance card," it can never hurt to have it along.
Dogs and cats require a rabies vaccination certification signed by a vet (specific requirements are available online
here) and there are some limitations on pet food imports.
While it's not a border requirement in any way, you'll want to fill up your vehicle's fuel before entering Canada as it's quite a bit more expensive there.
