Sudden death in healthy male mouse

Question
My healthy one year old male mouse was very active, ate well, no mites or problems with fur. He was a pet store mouse. He suddenly died. I examined him carefully for broken bones or broken neck, blood, or odd position of body. I could find nothing wrong. I read that mice can have heart attacks. How common is this, especially in pet store mice? He was more active than any of my other mice, but not abnormal. He was bright and playful and normal in every way.  

Answer
First off, I am sorry for your loss. His death could have been caused by several different things. Though he may not have shown any signs of sickness, he very well could have been harboring parasites, cancer, or simply died from a heart attack. Many mice don't live past a year, with around two being the norm. Since he did come from a pet store, and since most feeder breeders do not pay much attention to breeding healthy mice, he could very well have had a weakened immune system, or more likely to get cancer. Rodents are also very prone to respiratory infections. Did he have any sneezing, wheezing, watery eyes, or gasping before his death? I would watch your other mice for any signs of illness in the days to come. There are some viruses that can wipe out a colony or mice or rats in a matter of days. If you have any additional questions please feel free to ask again. Hope this helped!