Hi again, and thanks for your very helpful reply.
If you are adding any water to the wet blended food and you are keeping him hydrated with 100cc a day (sub-Q?), he probably doesn't need to drink much water on his own.
I asked all those questions about urination, because a cat that has a urethral blockage and can't pee, will sit or lay at the water bowl wanting to drink, but unable, because his bladder is full and he can't void on his own. In male cats, this is a medical emergency, as they must be catheterized in order to drain their bladder so it doesn't burst.
If he is peeing normally, it sounds like he's getting enough water through your feeding and hydration methods. He may be sitting at his water bowl and not drinking for various reasons. Something may have accidentally dropped into his bowl and he smells it and is afraid to drink. If the bowl is made of plastic, it may be retaining the odor of your dishwashing liquid after you wash it. Plastic is not a good material for food/water bowls, because they develop minute cracks that can harbor bacteria, without your knowledge. Try glass or ceramic bowls and wash them with hot water and a drop of dishwashing liquid (plain, without 'crystals' or bleach), rinse well in cool water and air dry.
I understand how you feel re: the tuna water and it's amount of salt, but you can purchase low-sodium tuna in water and offer the water drained from the can for him. You can also offer him 'Cat Sure' which is like 'Ensure' for humans who are not eating well, on their own, but check the sugar content in it, before purchasing.
Giving him water via syringe is not 'waterboarding' and if you give small amounts, several times a day, this should be fine; however, as I mentioned, he may not need extra water if he's getting 100cc's a day, subcutaneously. However, I would put a call in to your vet to report Max's non-drinking and ask if he needs to be seen, if necessary, to test his levels and blood glucose, through blood and urine testing.
If he is lapping the 'gravy' from his canned food, there should not be a problem with his tongue or the inside of his mouth, but I would check for any foreign objects stuck between teeth, under tongue, in the roof of the mouth, between cheek and gum, etc., and for any sores in his mouth or on his tongue, which may indicate stomatitis.
For now, I would not force him to drink water. If he feels he needs it, he will drink; he also may be drinking when you're asleep or not watching. Cats are typically 'secret' drinkers, anyway. For the health of his mouth, he should be getting moisture into it, but this is most likely being accomplished by the syringe feeding of the wet food. Add water to that food, if you're not, already.
You're doing a great job at keeping him fed, so he can have his insulin in addition to keeping him hydrated with the sub-Q fluids!
I hope all will be well with Max and please let me know how he's coming along. Thanks!
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