newly bought mice keep dying

Question
We got 3 mice for my daughter 2 weeks ago. The 1st week one of the mice
dyed suddenly. He had a bulge on his neck, he looked like he couldn't breath.
The second mouse dyed today suddenly. He started running around the cage convulsed and fell over. I cleaned the cage out with bleach and water and put
the remaining 2 back. Now one looks like he is breathing fast. I am worried
that something will happen to him also. What am I doing wrong. I know they
are just mice but it is hard to watch anything die. I feel helpless.

Answer
Dear Lori,

I'm very, very sorry.  Poor little things.

It's not your fault.  Unless you didn't feed or water them, or exposed them to chemicals, extreme heat, or extreme cold, this was out of your control.

The mice obviously came from the pet store already sick.  The suddenness and simultaneity of the deaths suggests that it was not a genetic defect (for they could be brothers), so they were already sick.  It might be worth calling the pet store and telling them that they have a contaminated cage, but they might not care.  Of course, never buy animals from that store again.  You ought to be able to get your money back as well.

An emergency trip to the vet might get Mouse 3 antibiotics to get him well.  That possibility has to be weighed against the cost (it costs as much as any pet) and the likelihood that he is pretty far gone if his friends died of the same symptoms.  Otherwise you need to keep him warm and make sure his food and water are accessible.

I can tell in another way that it was a bad pet shop because they never should have sold you three males to live together.  Except in a few cases where litter mates have never been separated, male mice can't live together.  They do fight to the death.  Thus if he survives, he will not want a friend.  Girls need to live together.  Still another male mouse or couple female mice in a cage next to his will keep him company.  They do communicate in little high-pitched squeaks which we can't hear.

If you reuse the cage for more mice, use bleach to wash, or boil, everything you can, and  throw away the rest.  When you go to a pet store, make sure NONE of the mice in the cage look sick, unkempt, have bald patches, or wounds.  In fact you might want to look around to make sure other animals look healthy too, to see if the store is careful with its animals.

Best of luck in the future in mouse owning.    Again, I am so sorry about the bad start.

squeaks,

Natasha