Cat aggressive toward puppy. Help!

We've had Duke and his sister Daisy for about a year now and they'll soon be three. They were adopted when our neighbor entered hospice care. Her kids were going to chuck them outside to fend for themselves! I wasn't about to let that happen so we spoke to them and they agreed to just give us the cats and everything they had for free. They have never been aggressive cats. A little skittish on Daisy's part but Duke has always been very friendly.

Until recently.

I just brought home a twelve week German Shepherd puppy, Jaeger [for Pacific Rim, not the alcohol]. He's a very calm, well mannered puppy, perfect for therapy work which is his intended goal, and it took me forever to find him. He doesn't chase the cats or instigate. He's never even approached them. The moment Duke laid eyes on him, his back arched, the hair went up and he went after him. Every time he enters the same room as Jaeger he does this, swats him [has made him bleed twice and me more than that. I get between them when I see it coming] and runs off again. There's plenty of information and articles dealing with Dog vs. Cat situations but I can't find anything that covers a situation where the dog is not the aggressor. I'm assuming it's territorial since Jaeger doesn't bother them but what can I do to fix it? He's being trained to help my grandmother who is wheelchair bound so it's important we make this work. Please help!

 

Welcome to the forum, and sorry to hear about your situation! Judging by Jaeger's body language, do you think it's offensive or defensive aggression? There's some useful information here: http://www.aspca.org/pet-care/cat-care/common-cat-behavior-issues/aggression-cats

 

Cats often need time to develop relationships, what i would suggest is keep them completely separated then gradually allow them to associate depending on their behavior around each other.