Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am very sorry to hear about your older fellow's continued dripping bloody urine despite two rounds of antibiotics and intravenous fluids.
There are many reasons to have blood in the urine.
We often think of infection but also crystals or stones in the urinary tract, masses in the urinary tract or clotting disorders are other possible causes.
Are his gums and tongue white, pale pink or bubble gum pink? If they are nice and pink then he likely hasn't lost enough blood to make him anemic.
Is he bleeding only when he passes urine (is he constantly straining and dribbling urine) or does the bleeding seem independent of passing urine?
If the bleeding is when he passes urine then concerns would be a genitourinary tract infection, crystals or stones in his urinary tract, a clotting abnormality or a mass in his urinary tract.
If the bleeding is independent of him passing urine the concerns would be trauma to his penis, a mass in his prepuce or on his penis, or a clotting abnormality.
So until we have a diagnosis a recommendation for meds is hard.
If he were my patient I'd start with a urinalysis with culture and radiographs of his abdomen to look at his kidneys and bladder for signs of stones and the size and shape of his bladder and kidneys.
If he had pale gums signifying significant blood loss then I would want to check his clotting function too. It sounds like blood tests have been done and were normal, did they include a clotting profile?
If money was very tight and there were signs of infection on the urinalysis then an antibiotic prescription for 10 days would be reasonable to start. It sounds like this has been tried and was not successful. It is also possible that he has an infection that is resistant to Amoxicillin, thus my recommendation for a culture with sensitivity testing to see if he has signs of an infection and what antibiotics the bacteria are sensitive to.
If I saw lots of crystals or abnormal looking cells on the urinalysis I'd warn the owner that things may be more serious.
And I'd recommend a recheck of his urine at the end of the antibiotic therapy. If there was still blood as he has then radiographs or an ultrasound of his bladder/kidneys is needed.
I understand that you may be frustrated with him not improving, and I wanted you aware of all the possible causes and what danger signs to look for which point toward the need for emergency care.
All you can do for him at home is encourage fluid intake to flush out his urinary tract. Add water or low salt beef or chicken broth to his food or feed him canned food. Offer him fresh water frequently. Perhaps use a kitty water fountain to encourage him to drink more.
If he is straining but unable to pass urine, is vomiting or refuses to eat, runs a fever (more than 103F rectally), has a tense, painful abdomen with gentle pressure, or his gums become very pale it is time for emergency veterinary care.
Let me know if you have any further questions.