I have recently added a rescued cat to the household. Strangely my female Chi and the male cat get along just fine and even play with each other (The cat gives the dog headbutts, and the chi licks his face).
The GSD however, which has been kept apart (because of his high prey drive) started whining (howling & crying) non-stop since the arrival, and even more intensily when I call the cat.

What should I do to modify the dog's behaviour?

Sorry to tell you that a gsd with high prey drive will not change,and will kill the cat if given a chance.The cat is a rodent to the dog and always will be.My whole house had to change after i got a 1yr old male stud, he has gotten to a 15yr cat 2 times, was shaking the life out of her, he could have killed her but went after her like a toy.She is fine now but not taking any chances.Get the cat a house tree so it can get away,but my advise is to be really careful.Shepherds are smart and will find a way and if the dog is winning it is paying alot of attention to the presents of the cat.My female was raise by my cat,sleeps and eats with her.So you can see my delima no solution just be careful to keep them apart.

I got a one year old kitty from the pound (who had never been around a dog before, much less two Rotts!) when my male was 2. He wanted to eat her as any driven dog would. I kept them separated for one month before allowing any contact and then on a leash for another month. My female had grown up with cats, so she was never an issue...

Quinn was crated while the kitty was out in the house (she was limited to a couple of rooms for a while and slowly allowd more freedom, she was also kept in a single room while Quinn was out) and he would go off in the crate, barking and snarling. We corrected him for it and eventually he chilled out and just stared at her while she walked around. He was not taken out until the staring was just a glance instead of a “Just come a little closer…” look.

When he was more relaxed (4-6 weeks) I took him out and had him tethered to me. I would correct a hard stare, but by now he was used to her presence. After a couple of weeks of that, he was fine while supervised and off leash. Another month and fine unsupervised. He will even let her come into his crate.

If you take the right steps, and as much time as needed, they can become friends; or at least understand that kitties are not food. There may be a rare dog that cannot be safe around a family cat (and by that I mean the cat that he has become conditioned to, Quinn will still chase any other cat that runs from him&hellip and a dog that has had the satisfaction of catching and, God forbid, killing a cat may fall into that category.

Here they are six months later:
Quinn and Jasmine

Jasmine and Quinn

Wow, nice work! And maybe there is still a chance for the GSD and the cat.

be very careful!!

Prey driven dogs are dangerous to cats. My boxer, Ava, has killed several cats. My clients, friends and family have a hard time believeing such a kind loving dog could kill.

My dog is acting on instinct. We have an old fat cat that she leaves alone because the cat doesn't run and this not prey.

Our problem is that Yote wants to play with the cats..... but he wants to play with the cats like he would another dog. Which means paw slapping, chasing and mouthing. He does tend to get overly exicted if the cat plays back and I have to watch very closely.

But even though his intention is not to kill them death is a real possibility when a 7- lb dog is trying to rough house with a 5 lb cat.
Since he is not being aggressive or going into full prey drive I just watch the interaction closely and correct when he gets too rough or bothers them when they are sleeping.


But they can only safely do this in the house, outside is an entirely different issue and if the cats run they are in real danger as his prey drive kicks in. Other cats are not a part of his pack and I'm sure would be fair game just as squirrels, birds and rabbits are.