Sally, are you using a finer gauge needle? The ones the my vet used and gave us for Galen (when he had acute kidney failure but is now cured) were 18 gauge Monoject brand "harpoons"! We researched and got Terumo 2O gauge needles instead. The Terumo needles have thinner walls so a 20 gauge Terumo can give almost as fast a flow as an 18 gauge Monoject. The Terumo needles went in easier. If you don't use Terumo 20 (or 19) gauge thin wall needles, I recommend that you try them. Things might go easier on Sven.
Here is a good site about the differences between Monoject and Terumo thin wall needles:
http://www.zzcat.com/CRF/supplies/AboutNeedles.htmI ordered the Terumo needles from
Lambriar Vet Supply. I didn't need a prescription in my state for the needles. California, Connecticut, Delaware, New Hampshire, New Jersey and New York require a prescription for needles. You can get 100 needles for a bit over $5.00.
He also might not like the feel of the fluids going too fast with you squeezing the bag. I'd not do that. His body needs some time for the fluids to spread out, and if you squeeze them in too fast, the fluids will make a pressing feeling inside under the skin before it has a chance to spread out more under the skin. Aside from it maybe feeling more uncomfortable with the fluids going in faster, I'd worry about air bubbles forming which would also probably feel uncomfortable.
Do you warm the fluids before administering them? Many cats feel better about the fluids going in if the fluids are warmed. The safest way is to fill a bowl or pot full of hot tap water, then set the fluid bag in it for a short while. Of course, you would always squirt some on your wrist first, to make sure the fluids are warm, not hot.
We always gave Galen a treat just before he started the fluids but while in "ready to receive fluids" captured and held position, to try to make getting the fluids have something good. Not he ever thought getting fluids were good, but he did like getting the treat. We used to also give a treat after the fluids were over, but that turned out making him want to break away to get it over with so he could get his treat faster. So no treats right after getting fluids.
I don't see a problem with Sven standing while receiving the fluids, as long as you hold him in place so he can't trot off.
Sometimes a cat doesn't need the full amount of fluids that particular day, so if you get close to the amount the vet said, but Sven is really fighting to get away, let him go. It really isn't going to make a lot of difference if one day you get 130 ml in him instead of all 150 ml.