Can dogs have bladder infections?

Just like humans, dogs are prone to having urinary infections. Especially when, as you have mentioned, they hold it in and when they lack water. They may also get the infection from dirty intakes of food or liquid. You must make sure to always have accessible clean water and there is always an available spot to pee onto and avoid making him wait for you just for him to go pee. If your dog continues to act te same way, you must take it to the vet as soon as possible to check any further infections.