I think what other members are trying to get across is that you should re-home them together. No one is saying let Prince suffer without vet care of give him anything not prescribed by a vet. Regardless, if you do re-home Prince then I would NOT let Sweetie have 'visits' with him. This will only further stress them both when you have to separate them once again. Once you break the bond, keep it broken. Do not further confuse them by having 'play dates' as they will not understand the concept.
That is just my two cents.
Fenbendazole is used against gastrointestinal parasites and also known as Panacur. Did your vet mention he thinks it's parasite related? Because it's a dewormer I don't see why you would need prolonged use in the first place, that would be hard on the GI tract.
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