One of our dogs passed this morning.
Out of the blue she was fine and running around, then suddenly she layed down and wouldn't get up.
We rushed her into the vet and about 15 minutes later she died.
We had them do an autopsy and they found she had an infection from recently being in heat and it got into her blood stream.
She was about 8 years old and we kept telling ourselves we wanted to get her fixed, we just never got around to doing it. Crazy thing was we finally made the appointment, she was supposed to get fixed next week.
Please don't procrastinate. Just go get them fixed. You may be saving their life.