I am sorry your boy has this trouble. It sounds like interstitial cystitis which is an inflammation of the bladder.
Read more here:
Esteemed authorities believe this is caused by dry food.Please read articles written by a feline vet:
The danger with a male cat is that he could block. That would be a life threatening EMERGENCY! At this point Simba should be fed wet food ONLY and be scripted anti-inflammatory medication.
He can have 3 drops of cranberry juice every day for ten days (by dropper) to change the PH of his urine.
Up his fluid intake to flush out his bladder.
He may need to eat a renal diet. If so, it should be a wet version like Royal canin.
Please let me know how Simba is doing.
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