I live in a semi-rural area in the UK, and enjoy walking with the dogs. However both my dogs are very playful and given the chance love to to chase sheep. Any tips on desesitising playful dogs against wanting to chase sheep.

Well first off you want to make sure that your dogs are getting the amount of excersice they need depending on what breed of dog they are. Dogs with too much energy won't likely pass up a chance to chase anything.

Provided the above is fulfilled you can try to avoid having your dog chase sheep by teaching them the "Watch Me" command. All this requires is that your dogs look at you and disregard everything else. It helps so that (if they haven't seen the sheep yet) they'll most likely overlook them and not chase. To make this effective the command has to be well rewarded and more 'game' like so that they actually want to do what they are told.

Also make sure that your recall is well ingrained in them. That they know and obey the command 'come' when it is issued. There a few ways to do that, I've outlined some of them here: http://k9domain.org/basic_commands.aspx

Hope that helps and best of wishes on this issue!

Your dogs are hyperactive just like mine. My dog also chases other animals just like chickens.