Did I make my dogs into monsters?

Hey y’all, hopefully it’s okay to post things like this here. It’s just been really bothering me and I hope to get other people’s perspectives on the current situation

My family, but mainly I—raised two beautiful male labradors for a year, then sent them away to my grandparents due to our neighbors complaining about how loud they are (but that’s besides the point). They live in a beautiful little ranch.

When they were growing up, I gave them a very realistic, almost life-sized dog plush that they loved to play with. After a while, it had gotten ripped apart and shredded to bits. They’d basically play tug-o-war with it. My memory’s a bit foggy, but I’m pretty sure after I took the dog plush away (as it was literally already mangled) they didn’t really like playing with the other dog toys I’d try to give them.

At the time, I didn’t see anything wrong with my actions. I honestly gave them that plush because I thought it’d be cute that they have a toy who sorta looks like them.

After about three years of them being in my grandparents’ care, we’ve gotten seldom news of them ripping apart animals in the ranch. The first one was a chicken, which my grandparents brushed off. Then they killed my grandparents’ kitten, which led to them putting them into dog cages and only releasing them periodically.

Just yesterday, my grandparents shared a video of them all bloody—then another video of one of their sheep, hiding in a corner with cuts on its face and legs. They attacked the sheep, and it would’ve gone farther had my grandfather not gone outside and pulled them off. Apparently, it took a long time before they let go of the sheep and he had to ask help from my grandma.

I feel horrible, but my parents are reassuring me that that is just their nature. However, I believe i took part in their current behavior or even outwardly caused it. I think my grandparents don’t want our dogs anymore, and I don’t blame them.

Any advice? And is their behavior directly caused by me?