Aggressive female Aussie
We had 3 dogs; 10 year old neutered Golden Retriever, 6 year old female Aussie who still has 1 ovary so she goes into partial heat, and a year and a half old non-neutered Morkie. For the most they get a long well. My daughter came to live with us and brought her 3 year old Labradoodle, neutered. My Aussie has taken to spontaneously attacking the Labradoodle. She also has become very possessive of the Morkie and has started humping him even though she is not in heat. Why is this happening and how do we stop it?