We recently got an 11 month old mini pinscher. For the first 2 days he was OK, but since then he has started peeing and pooping in the house. We had already had a 3year old male pit and 8 week old male mini pinscher when bringing the newest into the pack. He has no problem with doing his business outside, but has no problem doing it inside either. It seems as though it's mistly marking his territory. He will pee and poop in the house. Can anyone offer any suggestions? I might add that neither of the other dogs are messing in the house anywhere. The 8 week old puppy is pee pee pad trained and we keep him in a different room from the others.

Each dog is different and as long as there's no true medical issue, it could simply be a matter of training to his new home. I've found it quite helpful to integrate him into the pack which INCLUDES You! You are the pack leader. Take all of the dogs outside to do their biz. Keep him on a leash and only allow him to go where you allow which could be along the property line, etc. Do this multiple times per day on a fixed schedule. You can try treats but I haven't found that helpful over time for myself. This is a start, there's many other tactics, but I've found this works best for me.

Help her hit the nail on the head.

Age doesn't matter when it comes to potty training. At 11 months of age most people would expect a dog to be potty trained, but most aren't.

So you're training from square one. You have other dogs, dogs that are potty trained. How did you train them?

My method is observance, and reward. In other words, watch the dog, when he starts to pee or poo inside, a firm no, and even if he's mid poo or pee, pick him up, take him outside, and tell him to do his business. When he does, outside, then tons of praise, a treat, lots of "good dog".

If he makes in the house, then a firm no, and ignore him. Dogs are pack members. When the pack leader ignores them for bad behavior, it teaches them to do the behavior wanted.

No punishment ever. No sticking the dogs nose in his pee or poor. Big no no. It's about teaching him what you want from him. It takes patience, and a lot of time and effort. But isn't he worth it?