Something else that hinders progress when it comes to Yorkie potty training is the fact that they are prone to developing regression. This is where a fully trained doggy with no recent history of accidents suddenly forgets all their training and turns your home into their potty.
This might be a little annoying for you as the homeowner. You probably thought you were done with the whole training and treats routine. However, it is a common problem that is very easy to fix. The key is to understand what caused the regression in the first place.
Before we begin, just to address a common misunderstanding. Having their tails docked is not the cause of potty regression in Yorkies. There is no research whatsoever on this correlation.
One of the main culprits is a change in the environment. Maybe you moved to a new apartment. Maybe you adopted a trained pup and moved them into your home. It takes the little furry buddies time to get used to new environments. And often, this is accompanied by more than 1 behavioral regression like back to more frequent barking.
You may therefore have to train them afresh and teach them where they can go. The good news is that this process is a lot easier and faster than first-time training. Just find a nice spot where they can feel comfortable and get familiar with it and the new routine.
The regression could also be due to psychological issues. If the pooch suffers some kind of mental trauma, they tend to have periods where they forget basic skills they had been trained in. You should get the psychological issues handled first by a professional. This is because restarting training without addressing the trauma will be frustrating and unfruitful.
Certain events can also trigger such accidents. A seemingly routine normal event like pregnancy, regular shedding season, or being in heat might be the cause, although there is no proof of such cases happening.
Finally, the regression could just be a sign of underlying physical illnesses. These range from bladder irritation from urinary tract infections to overall incontinence due to spinal issues which Yorkies are known for occasionally having. As with the psychological issues, the only way out here is to get a vet involved to solve the root problem before resuming training.