death of my Chihuahua

Question
Last night my small (4 lb, 6 year old) Chihuahua died.  She was outside with my husband and our other 3 dogs (all small).  He heard some noise under the garden trailer where she was investigating something and when he called them in, she didn't come.  He went to look and found her under the trailer, having a seizure.  He brought her inside and called me.  Her eyes were popped out and her head was off to one side.  It looked like she had a very small wound on her neck and on top of her head.  The head began to swell very quickly.  We put ice on it.  We were trying to figure out what happened and thought that one of the dogs might have bitten her.  We were discussing about taking her into the emergency vet (it was about 11 pm) or just watching her at home to see if she improved.  Within 30 minutes, her legs became stiff and extended and her breathing quickened then stopped and she was dead.  She did not appear to be in any pain because she allowed us to touch her head and clean the wounds.  She also did not cry out or whimper.  In hindsight, I of course feel guilty that she died so quickly while we were trying to decide what to do and how to help her.  I also wonder if she could have been bitten by a snake?  We live in TX.

Answer
I'm sorry for your loss, the bite does indeed sound like a snake bite, and for her to die so quickly sounds about right, which if this is the case you need to get someone out there to try and trap the snake, in the meantime watch your other dogs like a hawk! That is so sad, my heart goes out to you. Please leash the dogs from now on, I'm in Florida and we have the dangers of toads and alligators, so even though my dogs are in the backyard I still leash them.