ive searched but couldnt find the thread, at what week would one be able to hear the ''galloping horse'' heartbeats using a doppler and is the frequency the key?

I can pick them up at 4-5 weeks with a Doppler and 6 weeks with a stethoscope.

I can pick up pups at 21 days with a doppler - as long as it has a dog probe, not a human one or large animal as some are out there. :)

And I think of it as a train noise. :)

Thanks WC any tips on where to go, to buy one? ive had a look at medical grade ones on a website beginning with M cant remember now, its on bookmarks on the PC but around £200 ( id like a cheaper one for starting out) and ones that midwives use. My neighbour has just mated her Border T bitch and I would like her to be my guinea pig and see if i can hear the heartbeats and save her a trip and £s on getting a scan. Ill never forget my first child's heartbeat sounded like an old steam engine 'clickety clack' as ringo would narrate lol, What freq is the dog probe and do you need to shave and use gel? She would kill me if i clipped her coat, as she is heavily shown.

Certainly.  Talk to Mike Brampton at Thames Medical mike@thamesmedical.com and he will sell you the right equipment.
Human pregnant tummies, if you think about it, are far larger than the average dog pregnant tummy and so the human probe will be too deep and go out the other side!  Similarly there are other being touted for dogs that were actually made for pigs which don't give reliable results for the same reason.
You don't need to shave but wet the coat well with warm water before applying plenty of gel.

Don't be frightened by the money (I've no idea how much they will be now) but a cheap one will be false economy and Mike will give you good backup.  I bought mine many years ago and it's served me well.  Say Val sent you! :)