Her mouth was open as if she had been trying to breathe. Is it possible
she choked on something? I find myself wishing more and more that I had
looked down her throat to at least rule out choking.

It's common for their mouths to be open and eyes slightly open when they die.

She was neither bloated nor dried out. Her carcass was in very good
condition. Even her fur looked good, no patches out. There was a spot
on her left forearm that looked as though she had been licking it...it
was smoothed down and looked like it had been wetted.

She may have been hit by a car. Sometimes they can just get nicked and that's
enough to kill them with no exterior signs of injury. I've picked up a few cats
and squirrels like this. I witnessed them get hit so I know it was a car.

Do you know how many panels are possible? I guess it would depend on
the number of different toxins possible, eh?

Mine tested for metals, rodenticide, pesticide and a few others.

Each state has a state health lab that does necropsies on animals to
test for poison or disease.

Do you know under what department or agency such a lab would fall?

It's basically called The State Lab. Ours is in San Bernardino, CA. Every state
has one. It's free if you don't want the results. Some people send in animals
for rabies testing or diseases like West Nile.

Mary, thanks for the info. It's very hard to think of this animal
suffering antifreeze poisoning, but it's better to know the truth.

God, I hope I'm not getting obsessive about all this.

It's good to know. If you have some jerk feeding them antifreeze in your own
feeders, you'd want to stop him.