Platinum Simmers have put together an article all about teaching a dog to find your Sim a date. Check it out!
Many previews (including ours) mention that you can fetch your Sim a date with your dog. But how exactly you can do this was quite difficult to figure out! With the help of Daniela from Italian Sims fansite Sims3Cri we figured it out!
First train your dog to at least level 5 hunting skill. The first hunting skill point is obtained by your sim training the dog to hunt, after that the dog can train itself by sniffing out collectables.