Handling dog aggression and introducing big dog to new little dog?
Here is as summarized of a breakdown as I can. I rescued my dog Serendipity (a boxer-pit mix) last year after finding her abandoned (leash and collar - no tag - still on) in another state. I adopted her and she has since lived with me and my parents and their (currently) 6.5 year old Australian Cattle Dog, Chase. The vet estimated her age as one at the time. Seren and Chase normally have gotten along, but over the 1.5 years they've lived together they would have rare, but true, aggression/fights over food, toys, and rare human jealousy. Seren quickly became the dominant of these altercations and Chase would flee as she would try to latch on to his neck. We figured out the triggers and have generally quieted these altercations. Seren is crated in the evenings to prevent anything and to not give her the opportunity to chew stuff in the house, and when she gets her meals. Toys are put up and neither is allowed to play with them when together. Also, constant vigilance is paid watching their interactions for signs of tension, in order to break it up before it can get started.
Seren has only exhibited home protection aggression one time when a cousin of mine (that she had been around several times in the past with no issues) came over to my parents. On that occasion she growled, barked, and tried to snap at him until we put her outside while he was over. He hasn't come back by since, but she hasn't done that with anyone else either, so we don't know what to make of that once instance.
However, over this last year I met a woman who has become my fiance, and I bought a house. My fiance has a 5 year old Dachshund, a sweet little fella named Alabama. While she, her pup, and myself have moved into the new home, we've left Seren for now with my parents while we try to figure out what to do. Our worries are the massive size difference in the two dogs (worried her jumping and hyperactivity could lead to incidental landing on his back and injuring him), the past aggression she has exhibited with Chase and him being a much smaller dog knowing he would more likely be killed or maimed in any kind of incident, and honestly my fiance's feelings of not wanting to be alone with her knowing what she's exhibited in the past and worrying she would be unable to break anything up if it happened.
When there are no issues, she is a sweet and hyperactive puppy, running, jumping, and enjoying herself in a fun and goofy manner.
The option of having to try to place Seren with a rescue is on the table, but it's obviously not my ideal choice. While my parents and I have learned somewhat to manage her specialness, I'm of course worried she'd go to a home that would be less accommodating and it ...