Do you guys have a product over there called Aloveen? They make a beautiful conditioner for dogs which is designed to be left in. Smells wonderful, and is quite a thick consistency. I massage heaps of this through their coats before going out, if I know we are going to get muddy, wet or prickly, and it makes grooming afterwards so much easier.
If I don't have any I just use a normal hair conditioner, but the trick is to slather heaps on before they get covered in burrs, and prickles.