I just saw another thread that might be similar to my issue... I have 6 rats, with 2 males being housed together. One of the males (they healthiest one of the group) was having what I thought was a seizure this afternoon. He's moving very spasticaly, holding his head up / twitching it. Very jerky arm / leg motions. He tries to climb but seems to have difficulty. He is close to 1.5 years old. The other male he is in with (he is slightly older than this male) has been loosing some hair and is very lethargic...I am not sure that his symptoms could be related, I assume it is just aging issues

None of the other rats are affected and show no signs. The only changes have been that I gave them a "whimzee" treat yesterday (none of the others showed a reaction) and that I acquired a pair of dwarf robo hamsters last week, but they are on the opposite side of the room and again, no other animals appear affected and the hamsters are OK. All rats are on the same bedding (thin layer of TSC pine pellets and shredded HT aspen on top) and the same food (NE).

I know that I may have to put him down, but I had a few questions for you guys about the situation.
1. Other than a brain tumor, what could cause this (trembling, balance, and weird head positioning)?
2. Should I isolate him in a single level cage (like a bin cage) until he is either euthanized or I take him to the vet?
3. Should I remove him from the room the other rats are in?
4. If I do have to euthanize, I don't have a co2 chamber ready yet and I don't have a snake big enough to feed him live to (my largest, a 3.5 foot boa, is on small rats and this is probably between a large and jumbo). Is cervical dislocation the best option or what else would be a quick and relatively painless way to handle it? I had to do CD on a small juvie rat once and I didn't do it correctly, so I'm leary of performing it on a larger rat).

Thanks for your help guys! This is such a weird and sudden issue and is the first time I've dealt with something like this in any of my pets, so it's freaking me out a little.