Bro I has a similar experience many years back. I moved from the city to a large acreage. I didn't have a good fence for my dog.
My dog ran off the second time we went for a walk on my new property.
I was devastated he was my boy.
Half Rottweiler and half Pit Bull. His name was Samson he was beautiful.
I had to go on.
Then one day when I came home from work 4 days later he was there at the gate entrance of my property worn and whooped but still my Samson.
Well we enjoyed our reunion for about four days but he had become different. When we went out side he no longer would mind me. We were walking along the fence a few days later and he jumped through the fence at a cow on my neighbours property. He completely ignored my commands and latched onto the cow. I had to physically remove him but he was not done. Then I had to be between him and the cow and capture him. Then I threw him over the fence(were in the neighbours pasture). He came back was not going to listen to me. This time I grabbed him and carried him over the fence and put him in my shop.
I went back to check on the cow, he would live but had a hunk of meat out of his rear.
I called the neighbour when they got home told them what happened.
Then I told them I was going to have him put down. They were shocked at my honesty didn't want me to put him down.

But I was there I knew I had lost control of a large athletic dog.
I could not take the risk of that happening again.

I took him to the vet the next day told the vet I needed to put him down. The vet asked me what happened took my money and I left. I had a feeling he also wanted to keep Samson he was a very loving and beautiful dog.

I don't know what happened but I have never had a friend like that again until I met my wife.
I still miss him today.