How long is it okay to keep frozen rats?

So about a year ago I ended up getting some 100g rats by accident since they got my order wrong. But I figured it may be time to try upping my snake's feed so I tried to give it to her. She didn't want it even though I was pretty sure she could eat it, but going from 2 50g rats to 100g one is a pretty big jump.
But now I think I need to up her feed, and I still have those 100g rats that have been in my freezer, in a freezer bag as well of course, for about a year.

I was wondering if the rats would still be fine to feed her?

Check them for freezer burn and if they have it throw them out. You wouldn't want to eat anything freezer burnt so your snake won't either. Other than that do the good ol smell check. Open the bag of rats and give it a good sniff. If it smells okay (like dead rat) it will probably be okay but if you get the slightest hint of a spoiled smell I would toss the whole bag.

Are they vacuum sealed? If so, they should be fine. I agree with Toad but I'd thaw one out and then give it the smell test. If there's any doubt about it's freshness throw them all away.

I always thought it was more related to the rating of your freezer but, despite looking, I can't find the thread I read that in. :(

I agree with the others. If they're sealed well they should be fine. But definitely give them a once over for freezer burn and then give them a smell check.

Assuming they pass those two tests I'd bet they're fine.

But....if you aren't sure or they're "on the edge" toss them. When in doubt, throw it out