The dog ate normally the night before, but the next morning I found it had blood in its urine overnight though it is still energetic.

Blood in urine has many causes; if more water helps, it is minor, but persistent cases need a hospital check. The main possibilities: first, a urinary tract problem such as infected urethra or bladder or ureter injury.

Second, bad diet like chocolate, onion or grapes, which are harmful and can cause bloody urine or even death; seek care promptly. Third, estrus bleeding in around 6-month-old dogs, which is self-limiting. Fourth, traumatic bleeding from the genitals during exercise that mixes into the urine.