XS doggie sweater patterns?

Greetings! I have a really simple request...I'd love to see if anyone can point me to a doggie sweater pattern...with just a few provisions:

1. I'd love for it to be simple and quick, so that it will have a chance of getting done amongst all the unfinished holiday projects.

2. It needs to be teeny. It's for a chihuahua and I've been told that XS items in stores don't fit her.

3. I'd love for it not to be a pullover type of sweater. The dog is pretty wiggly.

4. The person that's going to be putting the sweater on the dog has both Parkinson's and arthritis, so if it could be as easy to put on as possible, that would be great. I've even thought about modifying some patterns with buttons for Velcro.

See...told you it was simple! In all honesty, I know that's probably a pretty tall order, but I know that if it can be found, one of you can find it. I've been looking this afternoon but I just can't find a pattern that fits all of those things.