Strange problem with our originally-intended-adoptee-and-current-foster-dog Marley. (Been fostering him for a while now.) Brief background: Marley's a neutered male Australian Shepherd mix that we adopted 1 and 1/2 years ago from a recommended but poorly-run rescue. (Found out "poorly-run" only later!) He was claimed as "ignores cats and great with other dogs" ... important to us as we already had a dog-friendly dog and a few cats. At the time we did bring our dog to meet him and they were fine together, we didn't bring our cats because the rescue's director said we should not bring them because she had multiple dogs on her property and not all were cat-friendly. Short story: Animal aggression problems with Marley, "rescue" refused to take him back citing "already have problems with the county for too many dogs" on her premises due to complaints from neighbors. We tried training Marley regarding the DA and aggression toward the cats and were unsuccessful, so hired 2 professional trainers. Neither trainer could "cure" Marley of DA and his behavior toward the cats is specifically predation rather than aggression. With extensive research (though his tags and limited paperwork that came with him) we also found out Marley's true past history which was completely different than what the "rescue" told us. She claimed he was a surrendered family dog due to moving ... nope, he had been a forcible seizure due to neglect and had already had 2 more homes through a shelter and a previous rescue in another state. We found out he's an Aussie/Rottweiler mix, which we suspected, but the original "rescue" thought he was all Aussie ... nah, too stocky and his head's wrong ... we saw that from the start but it didn't matter to us. Also found out he was originally severely neglected from a pup ... left chained outside for 11 months and never socialized with anyone. Despite this he loves all people but is intermittently DA and considers cats/small animals as prey. So here's the very weird part ... Marley's intermittent DA only ever happens indoors ... he's perfectly fine with other dogs outside! A bit dog-reactive at times outdoors but never aggressive toward other dogs. Indoors it's a different story ... he'll seem perfectly fine with another dog indoors, but will then attack the other dog without warning and without provocation. (He only got to do the first attack and there were no injuries .... after that we would supervise and intervene if he tried, but he tried 2 more times ... we then began keeping him separated.) Cats we know we'll never be able to socialize him with ... they are strictly prey to him, along with any gophers or squirrels he happens to find outside. ANYway ... the question is: Has anyone ever known a dog to be selectively DA, as in only intermittently and only indoors? Any trainers have suggestions ... as we and 2 trainers are out of ideas? One trainer brought other dogs over and Marley was the same ... seemed perfectly fine with them, sometimes for hours, but would suddenly try to attack them ... but again only indoors. If it helps ... I should mention that Marley very quickly got "guardy" with me .... didn't want our other dog or anyone in the house near me. He never got aggressive toward my guy or my stepson but would very pointedly put himself between me and them anytime they tried to get near. If they continued to try to get near me he would move to continue to block them until I told him "No!" and made a point of letting them near me. Found out that when he was neglected as a pup (up to 11 months) in another state, the person who was feeding/watering and paying attention to him was a youngish female neighbor with very long blonde hair .... I fit her description so perhaps this is why Marley got so attached to me so quickly, to the point of being guardy? I trained him out of his guard behavior toward me, using both rewards and verbal corrections, but can't do anything about his weird intermittent-and-only-ever-indoors DA ... and neither could the 2 professional trainers. Both said they never heard of this very particular problem before! We had even tried me leaving the house for a few hours to see if he would be the same ... and he was. So his indoor-only DA is not related to his prior "guardiness" with me. Any suggestions/comments/previous experience with such a weird problem? This is his only problem, otherwise he's a fabulous dog ... and quite gorgeous!