My boy was attacked at 4 weeks old and had to have nightly soaks for a month so he has no problem with baths. I tell him it's time for a bath and he goes to the bathroom and jumps in the tub. I can even leave him without him running out. He stays til I tell him it's ok. Can you use your outside hose? Or put a towel in the tub for traction? Sometimes they don't like it cause they feel they will slip.
It's a nightmare to try to bathe little Jason. He fights every time. He hates the rain. Won't step foot out in it. He never bites but will use all his muscle to get out of the bath. It usually takes both my husband and I to bathe him and then the whole bathroom is soaked. He absolutely loves to play in the snow though. Our other two Kitana and Luna love getting in the bathtub. They even jump in the tub when we take showers. Its amazing how different they are especially when it comes to baths.
My dogs are both trained to "load up" in the tub due to me having a bad back, so I just lead my dogs into the bathroom, one at a time of course, and close the door and tell them to load up. They hop right in, I bathe them, and dry them off before they are allowed out, then I give them the "Okay" command, and they hop out of the tub and are ready to run around like crazy dogs lol.
It did take a bit of training to get them to the point of being able to tell them to load up though, as my girl doesn't like any sort of water except drinking water, and my mutt boy loves water, but despises bath time lol. He feels he practically has to be in my lap, so that's usually a "we both get wet" deal when I bathe him.
Ames' idea of a towel or a rubber matte in the bottom of the tub is a great idea. That's my boy's biggest issue, is he slipped when he was a pup and bumped his chin on the side of the tub, so now he looks like a cat when I try to back him up in the tub, claws out, attempting to grip nothing lol.
Some dogs just absolutely hate bath time no matter what you do, so just be prepared. Always use a happy voice, and don't fuss at them for shaking (usually if water gets in their ears), or for being afraid, but at the same time, don't reinforce their fears. I constantly tell my dogs they're good dogs, dirty dogs, smelly dogs, etc., in a happy voice, and usually get lots of kisses. My dogs are also trained to pick up each individual paw when I touch them so that I can clean their feet. But, this also comes from having owned a horse and being a groomer, so you don't have to go that far if you don't want to. I just find it easier to handle them this way.