older dog deficating on floor

Question
I have a 12 year old lab and a 6 month old german shepard. The lab has now started to go to the bathroom on the floor. I don't know what gives. The german shepard is being crate trained. Any ideas or suggestions

Answer
Why dogs do anything is speculative.  Start with a vet visit if the Lab hasn't been in recently.  It could also be showing resentment of the puppy because you are not the established leader, or stress.  

The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

Frequently dogs eliminate in stressful situations.  A 6 month old puppy can be a big stress to a 12 year old.  Our 14 year old lab now has the fifth new puppy to cope with since she was 10.  Most older dogs want nothing to do with a puppy and its biting games.  You need to work at teaching the puppy to leave the older dog alone.  Allow the older dog to give it warning snaps and growls.  Support it by correcting the puppy every time it starts for the older dog.  Give it an ''Ah, ah, ah!'' and offer it a chew toy.