My parents had an aggressive dog. It was a soft bundle of fluff as a puppy. It hated me. They got it after I'd married and left home so it didn't know me. It bit me twice while I was there. Once when it was laying on my foot while I was sitting on the sofa and I shifted and it didn't like it. So it bit me. I had an injection and 4 stitches.
Second when it escaped the front garden and had nipped a child playing out. I was the only person to respond to the child's plight and went out and grabbed it so it bit me.
My parents might have been rubbish dog owners, who knows? But this meant that I didn't visit my mother's house for the 10 years before she died. I couldn't go in the house or take my children in there.
It bit her, it bit my adult brothers and it was a really well cared for dog.
They didn't mistreat it, they fed it and walked it for hours, they took it to training classes. It was just a rogue aggressive dog.
Some dogs do have an aggressive streak that can't be trained out.
For the last 10 years of my mother's life, I couldn't visit her. They promised to keep the dog locked up a couple of times I went but it leapt over gates or kept up a constant yapping. I could not tolerate the noise or the risk any more.
So this small noisy and aggressive dog played a huge part in my not spending very much time with my family and not seeing much of my mother when I visited my home town, (250 miles away)
My memories of rare family visits are marred by the yapping and asking my mother to come out to the car to see me, because I couldn't take my babies in there. She was sad about it but understood that I couldn't possibly go inside.
It was a very aggressive dog. With no apparent justification. It showed no signs of being in pain or having any bad behaviour until it was challenged. Laid on the bed. Get off the bed. Nope. Growled and snapped until you let it stay. Fine and happy laying on the sofa. Until you told it to get off. The dog was not in any discomfort. It just thought it was the boss.
If my mother had taken heed of the signs early on, after the dog had bitten, and had it pts, I'd have different memories. My children would remember days spent on visits to their grandparents house being looked after and fussed and loved and playing games and whatever it is that grandparents do. My parents died whilst my children were 8 and 10 and they'd never set foot in their grandparents door.
Because of that fucking dog. Which is now dead. And it robbed my children of any sort of relationship with my Mam and Dad, their grandparents.
To me, that's a pretty huge thing.
So I do not think aggressive dogs should be given a 6th chance.