I team drive with my husband and 2 dogs, both Basenjis (barkless African sight hounds). One is 20 lbs, the other is 15 lbs. They are very clean, will even clean themselves like a cat, low-shedding, virtually no odor and as a breed, very easy to house-train. My male came from the breeder housebroken at 9 weeks (he knew to go to the door- but he couldn't hold it long), my female is a rescue from a puppymill who lived in a cage for the first year and a half of her life, and even without housetraining she adapted to life as a pet and was housebroken within a month with few accidents.
They have fresh water in a bowl in the sleeper at all times. I keep a big bowl inside a deep rectangular plastic storage container, so it's sturdier and contains any "splash". Rather than leave food out, I stop and they eat breakfast every morning around 9-10 AM, and have a couple of treats at night.
Most adult dogs can "hold it" reliably for 6-8 hours. Frankly, I need to stop and use the bathroom a little more often than that, about every 4-5 hours, so usually when I stop to pee, I take the dogs out real quick too. I find it prolongs my stamina on the road since I get up and stretch my legs a little more than I would if I didn't have the dogs. Plus they get a "long walk" about twice a day, usually at the start & end of my driving shift, or if I am laid over somewhere.
I have found some companies have a weight limit, and/or a limit on the number of pets. But, my dogs aren't negotiable, and my attitude is that if I can't find a trucking job that allows me to bring them, I'll find something else to do. So far, I haven't had a problem. I have a good MVR and positive references from previous employers that verify I kept a very clean truck, and in the last instance where I had to change jobs (company went out of business) having those references helped.
I love my pups and enjoy the fact that I have a job that lets me spend 24/7 with my dogs. Dogs were my first passion, trucking second- it was a choice between going to trucking school or dog training school. I figured trucking would be more of a guaranteed income, as dog training can be hit-or-miss when it comes to making a decent living. I have always said I'd be in heaven if I woke up every morning and spent the whole day working with dogs. This isn't QUITE that, but it's as close as I can get, right now. Maybe one day down the road I'll make a transition to working with dogs as a career, the older I get, the more tempting it sounds