Cocker Spaniels are usually super sweet, but notoriously stubborn with house-training. Pet store/puppy mill puppies can be even tougher, but not impossible. It CAN be done!
We've faced the same issue with a couple of our dogs, too. One of them was ... you guessed it ... a Cocker Spaniel! We came across a stepped approach that worked wonders for our little hard-heads. It took over a month, but it wasn't difficult and everyone kept relatively sane.
First and foremost, learn your puppy's signals. Most will sniff around in circles when looking for a good spot to "go." Watch the timing, too, to learn how long your pup takes to "through-put" a meal or drink. We had to have ours outside about ten minutes after a good drink, about twenty for a full meal.
Indoors:
- When your puppy isn't with you on a leash, keep him confined in a small area. A bathroom, laundry or mudroom work well. If you don't have a small room, try an oversized kennel. Baby gates are your friends!
- Cover the ENTIRE floor with newspapers. Any place that isn't covered with a bed needs to be papered. Make sure that no matter where he relieves himself, he's doing it on the surface you want him to use. You could also use puppy pee pads, but that can get really expensive.
- After a week of this, reduce the size of the acceptable surface. The idea is to make the bathroom area smaller without making the entire room smaller. If your puppy uses the smaller area, you can start reducing it every three or four days. Don't rush this part or you'll undo all your progress. Once he starts going off the papered area, you'll need to go back to square one again. Trust me on this one. We learned it the hard way!
- Eventually, you should be able to have a single pee pad/paper spot. At that point, we left the paper/pads up all the time, but our dog rarely used it unless it was an emergency. It was more of an insurance policy than an actual necessity.
Outdoors:
- Whenever you take your puppy outside to do his business, keep him on a leash until he finishes. As soon as he does, heap on the "Good Boy" praise! If you're in a fenced yard, let him off the leash to run and play with him. He'll learn that getting straight to business means getting on with playtime sooner.
- Always go to the same spot in the yard. Putting a used newspaper or pee pad there for encouragement can help.
- Choose a command that he can associate with relieving himself. It serves as a reminder, later on. Sixteen years later, our old pooch still knows that "Hurry Up" means it's time to "go," and he nearly always gets on with it.
Patience, consistency and persistence are all key to making this work. Just as in potty training a child, it takes time. Accept that there will be lapses and accidents, but in the end, you'll have a well-mannered family member ... and a cleaner, nicer smelling home!
Good luck.
Oh - and for the record ... your new puppy is adorable!