Thanks for the information. It would help to know the results of the blood work. Chances are that they were normal if the diagnosis was just a gastrointestinal bacterial infection, but it may help to see. The infection is not usually something they picked up from somewhere, unless they ate something rancid. Even then, their GI tract tend to handle stuff like that better than ours. The infection comes about when the normal bacteria in the GI tract is compromised (it could be something they ate that just caused an upset stomach or some type of metabolic disease, like liver, pancreas or inflammatory bowel disease), which allows overgrowth of more pathogenic bacteria, which already resides in the GI tract. It is called dysbiosis. It is not a contagious issue. If he didn't eat anything abnormal, then the concern is that it is a metabolic issue. A liver problem would have shown up on routine blood work. Inflammatory bowel disease and pancreatic issues (can go hand in hand with a liver problem) don't usually show up on routine blood work. A gastrointestinal blood panel to measure other parameters is usually recommended if a cat is not responding well to medications or is having a recurring issues. With his age, you also have to be concerned about intestinal lymphoma. An ultrasound is often recommended if there is strong suspicion of inflammatory bowel disease or intestinal lymphoma based on those results or clinical symptoms. The problem is that a biopsy is usually necessary to determine which one it is. I would make sure the thyroid value was evaluated withe blood work because hyperthyroidism is a common issue in older cats and can create similar symptoms to all of these. So, it usually is more complicated than just an "intestinal infection". If it has been a couple of days, and there is no response to medication, I would definitely have him evaluated by the vet again. It may be that just changing him to a different medication, like metronidazole, and adding a probiotic needs to be done; but most likely he needs some more testing. Please let me know if you have any other questions or concerns. Hope this helps.
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