Hi Customer (name blocked for privacy),
Thank you for the additional information. Given your dog's history of health problems, he really does need to be seen. I still think it is likely to be parasites or a protozoan infection, especially if another dog he has contact with has similar symptoms. Metronidazole is frequently prescribed for giardia (protozoan infection) which will cause those symptoms. It helps a dog fight the infection until the dog's own immune system does the job. If your dog has a lowered immune system it might take a longer course of antibiotics to help clear the infection as well. You might want to ask the vet about an immune system booster. Since organ failure can also cause foul breath, you will also want to have blood test done to ensure that there is no additional problems as well.
I would first get the fecal sample done and if that is clear, have Riley seen by your vet for bloodwork and a physical exam..
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Thanks,
Jane


