[InkyPen]

I agree that this is a hamster that really needs to see a vet, for his own welfare.

From personal experience, UTIs are very, very painful (as a human, only prescription codeine even touched the pain, to give you an idea). It was agony, that also involved feeling terrible and frequent vomiting (hamsters can't vomit....). I gather stones are even worse.

While cranberry juice is technically meant to help prevent UTIs, he's far past that stage.

I, too, doubt that this is food related. However, it's worth noting that Harry / Hazel Hamster is widely reckoned to be the best for Syrian hamsters, nutritionally speaking. There are plenty of safe treats you can feed - broccoli, peas (most veg, in fact), unsalted nuts, dried mealworms (in moderation) as just a few examples. There's no need to faff about with dog treats of questionable origin - the only dog treats that are known to be suitable are greenies and whimzees - both chews that are good for gnawing and wearing down teeth.

Please, please, please take him to the vet - ideally one that specialises in exotics, as hamsters are considered exotic pets in vet terms.