Hello. I cannot add more than what others have said already. It seems very likely to have been something that happened very quickly, though of course it could have been building-up without symptoms for a while. Some things don't present obvious symptoms. Typically, dogs suffering heart arrhythmia do become extremely thirsty, so a cardiac arrest is certainly a possibility.
I really just wanted to say how sorry I am to hear your news and particularly as Bandit was so young. In your grief, please try to think about how happy he had been, even for the few years he had - and that happiness and contentment was down to you. Although he passed all too young, he enjoyed a love-filled life, which not all dogs are lucky enough to enjoy. You are in my thoughts.
Run free Bandit. Tony x
Yeah, he was in the prime of life. Very sad.
Thank you all for taking the time to read my post and reply. I am devastated still, and your kind words and support and sympathy mean a lot to me. I thought about the day I would have to say goodbye to Bandit so many times in the past 4 years, but I never thought it would come about so quickly. I just can't believe it happened still.
GSD is one of the breeds in which hemangiosarcoma is prevalent. I am surprised the vet did not mention it. It is a type of cancer that is asymptomatic until shortly before death. It causes a tumor to form on either the spleen or the heart, and as the tumor grows, it becomes engorged with blood. Eventually the tumor grows to such a size that it ruptures, causing massive internal bleeding, and the animal goes into shock and dies very quickly. If that's what happened to your dog, there was no way to prevent it. The mercy is that the dog does not suffer long, but it is a terrible shock to the owners. I am so sorry for your loss.
I am so sorry for your loss! It's difficult enough to deal with losing them when they are old and have been ill, but for a young, seemingly healthy dog to just die for apparently no reason, it's so much harder to come to grips with. My heart goes out to you.
Your vet is correct in that more than likely he died of either a cardiac episode or an aneurism in the brain that burst. I seriously doubt that it was his food because even the treats that are made in China that have recently been recalled are not killing them outright, the dogs are getting sick and showing signs of illness for a while before they die. Of course, the only way to tell for sure is to have the vet perform a necropsy, but it wouldn't make the situation any better, so I probably would have made the same decision that you did and opted to NOT have one done.
Again, my condolences. You are in my thoughts.
Ghilly
Sorry you lost your friend, the dog had a very short life regardless of what the breed was. Still, it seems, large dogs have a shorter life span, some average no more than 8 years. So it seems possible to me for such a breed death by "natural" causes at age 5 my not be extremely uncommon.
I think you may be able to get some idea by looking at what you believe the dog was eating that day or the night before. I haven't noticed any dog food recalls lately, but a check (web search) on the brand of dog food your dog has been eating may lead to something.
The vet is your best bet for likely causes.