Excessive water pressure can also be a result of thermal expansion of the water within the home, even when the pressure entering the water supply is within the desired range. You home's plumbing spends most of its time as a closed container.
Most UTIs can be successfully treated with a course of antibiotics that lasts between 7 and 14 days. Antibiotics for dogs and cats, like Cephalexin or Clavamox, are the most common treatment for UTIs due to their ability to destroy and inhibit the growth of bacteria. Some veterinarians recommend a follow-up urine culture after antibiotic treatment is complete to confirm that the infection has been eradicated.
Typically, smaller breeds and younger dogs will need to urinate more frequently than larger breeds and older dog. The average healthy dog will produce approximately 10 to 20 ml of urine for each pound of body weight per day. Ideally adult dogs should be allowed outside to relieve themselves at least 3-5 times a day. Depending on how many times you stop for gas during your travel days I count at least 5 distinct occasions where your dog is given an opportunity to relieve herself. She is being given plenty of opportunities to relieve herself but it sounds as if she is only using a couple of them to actually go since you state 10-15 hours can pass without urinating.