Nacropsy: Heart Attack

Hi,
   
I had two male lion head rabbits (Chubby & Thumper) This morning I woke up and Chubby was dead. His brother was grooming him and nudging him. They are not quite two years old. This afternoon we had a necropsy done on him with the results of a heart attack. My boyfriend picked him up but did not ask too many questions.. and now I have so many. They have both been neutered and are in great health (Or so I thought.)
   
We have a cat who doesn't bother the bunnies, just walks around their cage. When we let the bunnies out the cat is never around yet they are still on edge. If they got spooked enough would this have triggered the death?
   
In the area where their cage is it is sometimes warm but nothing too extreme. Although they have lived in this area their whole lives, but would this have triggered soemthing.
   
Now that Thumper has lost his best friend, I have heard that this can make him die from a "broken heart". Is this true and if so I definately want to prevent this, so in the future I would like to get him a new companion. Should I get a male or a female? Should I get another lion head or will he be okay with another breed?
   
I could go on and on. but I'll stop now. If anyone could answer my post it would be greatly appreciated!
   
Thank you
   
Jessica

Okay...
   
Any mammal can have an undiagnosed heart problem. Without a EKG, you'd never know - apparently healthy 19 year old college basketball players have died of heart attacks. It can happen at any time.
   
Thumper will miss Chubby for awhile, but there's no reason why he can't have a new friend. I suggest getting a very young one, so Thumper can be in charge. I don't think the breed matters, just pick one with a generally compatible personality type to Thumper's.
   
The rabbits are on edge because a cat is a predator & they are prey animals, & predators eat them & they know it. Just 'cause the cat - or any other animal - hasn't lunged for them up to now, doesn't mean it won't later. So they're ready to run, just in case. (Of course, we had a cat who would play tag with our rabbit, so you never know what's going to happen with cats & rabbits. This rabbit also thought she was a funny-shaped cat.)
   
If you have more questions about the cause of death, write them down, put them in a fax or an email & fax or email them to the vet. The vet will answer any questions you have. He can email you the answers, perhaps. This saves them a lot of time, rather than doing it in a phone conversation. Ask the vet exactly what caused the heart attack, if he knows - was it a heart defect, or something else?
   
"If they got spooked enough would this have triggered the death?" Unlikely, or Thumper would have showed signs of being upset or scared.
   
"Now that Thumper has lost his best friend, I have heard that this can make him die from a "broken heart"."
   
Rabbits are prey animals, & if they got totally depressed & died of grief every time one of the members of the rabbit warren died or disappeared, there would be no rabbits in the world. Rabbits recover from friend loss far easier than dogs & cats. I suggest paying more attention to him until you get him a new friend, he'll appreciate the attention.
   
As to sex of the friend, I don't know about that. This question, I cede to other board members.

Thank you so much for your reply "ahtnamas." It was very helpful. We decided to go with your advice and we got another lion head rabbit. She is 5 weeks old and the cutest thing ever! We have not introduced them yet as I want the new bunny to get used to our house first. They are in the same room but no where close to each other.
   
I will definately take your advice and get in contact with my vet.
   
I just have one more question,
   
How should I introduce them? I have searched the internet but have heard mixed reviews.
   
Thank you, Jessica