Welcome and thanks for asking your question. My name is***** am a licensed veterinarian. I am happy to answer your question today. I am currently unable to make a live phone call I am sorry. But, I will be glad to discuss this on this thread.
In response to your quetion, bloody urine in a female dog can be caused by: Urinary tract infections, bladder stones, tumors or even part of a systemic disease. The fact that she was treated with Amoxicillin and the problem continues it is possible that if this is related to an infection the underlying bacteria could be resistant to the Amoxicillin.
I would recommend you discuss with your vet about doing xrays to rule out bladder stones. In addition, doing a urine culture & sensitivity (C&S); this test will isolate the underlying bacteria and provide a list of antibiotics that could be used specifically for that bacteria.
Finally, garlic is toxic to dogs; it will cause damage to the red blood cells leading to anemia. I would recommend you discontinue the use of garlic. Discuss with your vet about doing some blood work to make certain the blood urine is not related to something going on systemically.
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