To reiterate: It is one of the following:
1. Urinary tract infection.
2. Urinary tract infection with bladder stones.
3. Kidney infection with or without UTI and kidney and bladder stones(less likely due to her age).
4. Transitional cell carcinoma or other neoplasm of the urinary bladder (less likely due to her age).
5. If your dog is not spayed yet she could be having her first estrus (period or heat)
6. Vaginal or uterine infection.
I'm not a vet, but I'll comment until Dr. Cheng can respond. Any time you see blood in urine, there is a problem that needs veterinary attention. There are lots of things that could be causing this - anything from a urinary tract infection to kidney stones to cancer. In other words, don't waste time wondering what the problem is, just get her to the vet and have the problem properly diagnosed. Your dog is likely in some amount of pain from whatever condition is causing the bleeding, so please don't wait!
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