mouse convulses at death

Question
Dear Natasha,

Lately my love and I have been having problems with some mice from petco. They seem to be getting sick at alarming rates. We do everything we can to help them out, one of our newest are currently with a vet, and I've been administering Tetracycline (and a single dose of minocycline) to 4 of my mice with thanks to your helpful answers to a previous asker. Not more than a few hours ago, the first mouse I ever bought passed away. It's hard to even collect myself after what I just saw. I was just hoping you could tell me a little bit about her death.

Sexy, as we've named her, has been with us only a little less than a month (will be a month this Saturday), and she seemed less energetic a few weeks or so ago. Then she developed a humpback of sorts, a sign, we thought, that she was sick. We continued to play with her and give her love, and she had a cagemate whom she loved very much and always laid with, we've really done everything we could to give her the best life possible.

Not more than a day or two ago, we thought she was making a recovery. She was much more energetic, and running around her cage. I thought perhaps she was getting better. All day today, however, she slept. At about 12:20 AM or so we pulled her out (she was awake) and she slowly climbed up onto my arm, and slept on my shoulder as I did Homework. She looked pretty bad so we set her in her cage to drink and eat... but she wouldn't accept any of it. Then she seemed to have lost control of her legs. They seemed to just go limp and she just lied there on her side and stared at us. I was frantically trying to figure out what was wrong, and then she started to convulse. Very sharp, sudden movements and shaking. She seemed to stretch out a few times as if to yawn, or squeak, but couldn't. I tried to very softly pet her head a few times as she sat there writhing in these convulsions. I even grabbed some of her cotton bedding and tried to place it on her back, like a blanket. Then she shook violently a few more times, put her head down in the bedding, and closed her eyes. She had left us.

I don't know what exactly I just witnessed, it looked incredibly violent. I suppose the entire question on my mind is what do you suppose she was going through. Do you know much about the death of mice? Were those convulsions and quivers she must have had in the middle of the cage for a minute or two painful? I feel horrified, and I've lost a friend that meant very much to me, right before my eyes. If you know how mice typically die, or what exactly I witnessed and how it can possibly happen, I would feel better to know.

A sorrow heart,
-blake

Answer
Dear Blake,

I am so, so sorry about your mice.  You mustn't put any new mice with the ones which have been sick.  All items should be sanitized-- bleach or boiling water-- and those unwashable should be thrown away-- before any new mice should have contact with the items.  Your new mice must be completely quarantined from the old ones.  

Mice usually or perhaps always convulse at death.  I have never had any sign that it is painful- no mouse has ever squeaked at that time.  I have seen a lot of mice die-- my mice often ask to be picked up, even wait to be picked up, to die in my hand, which I take as a huge compliment.  They always convulse, some much more violently than others.  That's all I can tell you.

The humpback that you noticed is a sign of 'old age.'  I don't know what else to call it, though some mice get there quite early, due to sickness or genetic disease.  Usually a mouse doesn't last much more than a month after this stage, though I once had a mouse who looked elderly for 6 months.  It's definitely right to continue to give them lots of love at this stage.

I hope I have helped.

squeaks,

Natasha