Two days ago my very active healthy collie dog aged about five years old (approx rescue dog) dropped down on his back legs and died, in seconds, he didn,t gasp for breath just whimpered very slightly and died, we have had him for three years with no obvious health problems, this was extremely distressing for us, our older rescue collie (14) is fine but geriatric now, they were both walking steadily along on their leads, on a lovely grassy park, neither dog had been running fast, and the collie who died was not over weight, has any other collie owner had this happen to them?.

Oh how awful for you.  I have no answer for you, just sympathy that this happened.  I hope you can find out the reason why this happened, as it will help you to grieve.  Good luck, and my thoughts are with you.

Thanks, I've had so many replies, The vet seems to think it may have been a cardiac arrythmia (irregular heart beat) a time bomb waiting to happen, common in breeds where brother and sister may have been mated together, as he was a rescue collie I will never know, but it certainly helps if you know that this can be checked and some form of treatment given to these poor dogs, thanks again Flic coops

Really sorry to hear about this, what an awful shock it must have been for you.
It sounds like a massive heart attack.  Did you consider asking your vet to do a post mortem ? I know it's not an easy thing to decide but sometimes it's the only way to find an answer.
Thinking of you.

A fre4ind of mine ahd this happen to her 23 month old Elkhound bitch that I had bred in my first litter.  A post Motem showed all internal organs healthy and the only thing the Vet could think caused it was something in the brain.  She had sustained a kick to the head from a horse a few months earlier, so maybe there had been a slow bleed.

With her it was just as you describe a stagger yelp and instant death.  She to had not been running as they ahd just returned from a drive and she had got out the car and run up to the house and just keeled over.

The vet did say that occasionally there can be a massive surge into the brain of impulses that sort of casue a short circuit effect and sudden death. 

She found it very hard not knowing for sure what had killed her despite a Post Mortem, but she didn't want her head cut up.

What a horrible thing to happen - I really feel for you.

One of my former students had this happen to her two year old border collie.  She took him to the vet convinced that a young healthy dog could not possibly have just died and that the vet would be able to revive him which, of course, he couldn't.  She had another dog from the same breeder which seems fine - but then, so did the other one until he dropped dead.  She still has no idea what happened.

When a dogs heart fails it can be very sudden & I know of someone who had two brothers died the same way just out for a walk & bang he was gone & he lost the other 5 years later in the same way

It could also be a massive stroke

Sadly our pets cannot tell us if they are feeling a bit off & heart conditions have no pain as such & may have no symptoms at all.

{{{{hugs}}}} I lost my two BC boys last year so I know what you are feeling

This happened to my brothers bearded collie. They had been out for a walk, came back and he went and lay down in the garden but as it was raining he told the dog to come in. He did, went and lay down in the hallway and just died :( He was only 4 years old. My sister had his litter sister and she lived till she was 11, and the mother outlived them both.