Quote:
Originally Posted by kjc  I believe the older girl is the one with the problem, not the puppy... |
Sorry, mis-read it.
Then just re-adjust which one is subservient or ill. If this is a dog who has fitted in before now, she could be feeling bad and needs a vet check-up to be sure she hasn't occult illness, dental pain, etc.
Likely the other teen and the pup are now a pack/team and they are using their leadership qualities or leader-nurturing-puppy roles to tell the third dog what her place is in the pack for the present. Pack dynamics are usually directed by the most assertive, dominant dogs, the smartest, healthiest and wisest are acknowledged by the others as leaders and the other pack members of lesser abilities in leadership or skills will give place to the one dog or pair that step into the alpha dog roll(s). If there are two alphas, they are almost always a male and female or a leader of either sex with a yearling in tow. Usually the younger dogs are the more subservient but if the pup is now bonded with an older dog, that pup is still being puppy-nurtured or is a strong dog that is becoming almost an equal to the older, teen dog.
It may stay this way for a while or forever, depending on the health and characteristics of the 3 dogs involved. It could be your other two sense the third dog is ill in some way and keeping her at a distance, as some packs will do. I would get the isolated one vet checked from dentals to back problems to everything else, blood work, heartworm, the works - even if the last check-up was just a month ago - that dog needs a health check to be certain she hasn't broken a tooth or having an abscess, having pain from some unknown source, etc. If she's healthy, change treats and just watch how things go for the next few months and see what happens. Sometimes adding an extra dog can rock the stability of a pack in many ways in some packs while in others, they hardly miss a beat.