We have administered fluids, but I don't recall anything like this. Since you have no reply here, call the vendor or manufacturer. If nothing else, ask a vet tech at your veterinarian's office. I think there are some feline kidney failure forums which might be able to help you as well. Just do a search; you might have to join but it could be helpful to you.

Like socks, I've never heard of no air in the bag. Without air it seems there's no way fluid will/can flow out properly.

Scarry that you he was hydrated double the amount since that can cause major problems.

Here are 2 pics. The side view shows more of the "U" shaped suction, w/no air in the bag. His 1st 200ml dose from this fresh bag was suppose to end at number 2. I stopped the fluid at number 2, but it actually ended at a volume of 2.5, because of the slight "U" shaped draining (I was watching the fluid level by the numbers so didn't realize that he got an excess of .5ml of fluid till I examined the bag after we were done). I thought it was a little hinky, but didn't know this would happen next: So his next dose of 200ml was supposed to end at number 4, where the red marker is, but as you can see, the bag drained in a "U" shape again but even more so, when actually it was drained to number 6.5!! but as you can see, the fluid level is at number 4 if one is reading the level by the numbers! I have to dose my cat alone on the floor so I have to read the bag from floor level, which I never had a problem with, that's why I didn't realize the bag was draining weird since I was watching the fluid level by the numbers. I called the online store and they are replacing the 4 Braun bags I have left w/Vedco (DEEP, BPA free), the brand I am used to using. I'm hoping no one else will over hydrate their cat w/this story of caution. Thanks for all the feed back. Taz is doing great, no side effects of the over hydration (he's a big 18-1/2yr old Maine Coon mix @15lbs (was 19lbs @his prime. thank goodness!