Can Freshly Neutered Males Still Impregnate Females? And Why do Young Cats Suddenly Perish?
Let’s answer two more of Mrs. Kitty’s questions.
Is it true that you should keep a freshly-neutered male indoors for a week because he can still impregnate a female?
As I have mentioned twice in the last week, I would prefer that all cats were kept inside at all times. However, the answer to your question is yes. After the testicles are removed, it takes several days for all of the residual sperm to clear out of the pipes. During this time, a freshly-neutered male cat can still impregnate females.
It can take more than a week for the male’s testosterone levels to drop. During this time he will remain at increased risk of fighting, spraying, and engaging in other undesirable (from our point of view) behaviors.
What is the most common cause of sudden death in visually healthy young (2-5 years old) cats?
In outdoor cats, vehicular trauma is by far the most common cause of sudden death regardless of age.
But I’m guessing that you aren’t talking about the obvious.
In my experience the most common cause of sudden (and unavoidable) death in young cats is heart disease. Cats are prone to a syndrome called cardiomyopathy. This syndrome develops slowly but initially may not cause clinical symptoms. The first symptom of the syndrome may be sudden death.
Go to my website for more information about cardiomyopathy:
http://drbarchas.com/feline_heart_disease
Tomorrow: it’s time to talk about a dog.
You have questions. 
I’m sure that my first cat died from cardiomyopathy.
He was only about 7 years old and had a heart murmur.
He began urinating on the floor. I had a vet come to the home as he was a very frightened little creature who had been terribly abused before I had gotten him. The vet checked him for any infections but he had none, but a few days later, I came home and found him dead.
I did not have an autopsy done, but I saw that he was sort of going in slow motion for the last few days of his life. I typed in “Sudden Death in Cats” and cardiomyopathy came up.
I have a question about heart disease in felines, what are the symptoms? And what kind of tests can they run to test for it? Two of our three cats were basically rescues. We think Harley, who will be 7 in the Spring, was dumped. He just showed up one night in late May/early June, and we didn’t find anyone who was missing him. When he made his presence known that evening, he was only a few weeks old. Mittens, who turned 2 in July, is from a small farm just a couple minutes away. Bear, who is now 11, is the last surviving cat of a bloodline that had been with our family for many years. So while we know the history of Bear’s family (unfortunately, we don’t know how any of them died), we don’t know anything about Harley’s or Mittens’, except that Mittens’ daddy is a Manx and his momma is a mix.