Blood in the urine is rare in dogs from birth to 5 or 6 months old. Blood in the urine mostly occurs in adult dogs. There are many causes, such as bleeding mixed with urine during estrus in adult female dogs causing a false appearance of blood in the urine; male dogs after sexual maturity may have behaviors like hugging people's legs or other dogs and may have traumatic bleeding. True hematuria is mostly caused by kidney disease, urethral stones, bladder stones or urinary tract infections, tumors, thrombocytopenia, and certain medications. Therefore, the cause of the blood in the urine must first be determined, and then symptomatic treatment should be carried out based on the cause.