I adopted a little (big, actually) senior citizen guinea pig about two months before I got sober. Yes, I'm a 31 year old man with a guinea pig.
But I'd recommend that or any pet, so long as you ARE up to the responsibility of caring for it. My little guy (name's Cody) helps keep me sober-- he keeps me company, is dependent on me, and requires a little work. It keeps me clear in what I'm doing to know I have this little creature depending on me too. He needs food, water, and love. And to be kept safe from the dog.
That's my two-cents: having a pet to care for (albeit an easier pet than a dog) has been a joy and has aided me in my recovery. Who's gonna take care of Cody if Daddy's skunk drunk?
Dave