Q. It appears my little one has blood in her urine. How can I determine if she is in heat or has an infection, etc.?
A. Usually when a female begins her best you'll notice some slight change in behaviour just before hand. You should notice some physical changes as well like swelling around her vulva. When she begins to bleed you may notice it when she goes to the bathroom but usually they drip a little the rest of the time as well and you should notice droplets quite frequently
Blood in urine is usually a sign of infection (if as you stated unless she is in heat). Sometimes infections have smelly discharge but not always.
I would rather be cautious and recommend you have the vet examine her to be sure it is not an infection as this is best caught early if it is