Ok, thank you so much for all of the extra information.
In an older dog, my two biggest concerns for increased water consumption and increased urination would be diabetes
and kidney disease/failure.
With diabetes, they cannot regulate their blood sugar, and therefore more sugar is passed into the urine. Since sugar is a big, what is called "osmotically active" molecule, it pulls more water into the urine than normal. Therefore, they urinate more, and to compensate to drink more.
With kidney disease, the kidneys aren't working as efficiently to conserve water, so more water is lost into the urine, and they must drink more to compensate.
With both diseases, there can be weight loss (though it sounds like her weight loss was intentional), but usually with diabetes, they have weight loss in the face of a ravenous appetite.
So, you may ask, how could kidney disease and diabetes relate to the original question about blood in the urine? With diabetes, since there is more sugar in the urine, it is a perfect growth
medium for bacteria, and subsequent urinary tract infections. It is very common to have blood urine with urinary tract infections. With kidney disease, they are also at risk of urinary tract infections (which can also have a role in worsening the kidney disease), which can also cause bloody urine.
There are other reasons for blood in the urine, including trouble clotting the blood, tumors
in the bladder, and other causes.
If your girl is still eating, drinking, and able to urinate (even if there is blood in it), there probably isn't a need to rush her to an emergency hospital. However, if she develops vomiting, diarrhea, anorexia, is straining to urinate, or is unable to pass urine for more than 12 hours, then those would be indicators to seek emergency care, since these can be signs of more serious illness (or serious complications from kidney disease and diabetes). Other reasons to seek veterinary care would be excessive amounts of blood in the urine, weakness, lethargy, trouble breathing, or any other concerning changes in your girl's overall attitude and demeanor.
As soon as reasonably possible, I would recommend taking your girl to your veterinarian for a complete physical examination. Kidney disease and diabetes can be diagnosed with bloodwork, so after her examination, I would recommend a complete blood count (to assess red blood cells, white blood cells and platelets), a serum chemistry screening (to evaluate liver and kidney function, and blood sugar) as well as a urinalysis and urine culture (to better evaluate kidney function and rule out a urinary tract infection).
Based on the results of this information, your veterinarian will be able to discuss and recommend the best course of treatment.
I am including some links with more information on diabetes, kidney disease, and urinary tract infections.
I hope this information is helpful, and that you are able to find out what is going on with your sweet little girl soon. Please let me know if there is anything else I can do to help.