My 2 year old male cocker spaniel has been going crazy on our walks for the last several days. He's pulling like mad and sniffing frantically all over the pavement. I tried stop/start but he cried or barked. Then I realised he was over threshold and nothing I could do would stop him. Last night we got back to outside the house and he went mad with his sniffing. I managed to get him to come halfway up the drive and he just stopped. I waited and gave a gentle pull and he pulled back trying to get out of the collar (we usually use harness but he isn't keen and was particularly against it last night). The last two nights he's been crying at the front door to get out which he's never done before. The only thing I can think of is there is a bitch in heat who is walking along our street. I've taken different routes but he's still the same and he's the same for the whole walk. Not very enjoyable Anything else it could be? Any advice if this is what it is?