My brother and his wife have two kids that are grown up now. Several years ago they had a very nice golden-retriever named Simba. I would take Simba for a walk before I left my brothers house every time I visited them. Simba had a long good life but in the end she got a cancer in her leg. At first she could not go up the stairs to the second floor. Then one morning she was so out of it that my brother knew the day had come so he called off work and took her to the vet. Apparently cancer in a leg is common in large dogs.
Simba got along with everyone, even all of the neighbors and the neighbors dogs. But she had a special bond with my brothers wife. After Simba she said it was too sad and she would never get another dog.
Then one day her daughter was driving by herself at night and a dog ran out in-front of her car and she stopped before hitting it. She got out of her car and the dog got in. It is a big mixed breed but is probably more than 50 percent pit-bull. The daughter named it Zep because she was listening to led-zeppelin when it ran out in front of her. It is full grown but young. It had a chip and the previous owner is a trucker based in Florida who was in the Pittsburgh area and had it on a leash beside his truck at night and the dog chewed through the leash. The trucker said he does not want the dog back. Since my brothers family has had Zep he has chewed through two leashes, so now they have to use steel cable if they want to put him out on a leash. At first Zep was shy and afraid of everyone and everything, but after a while he came around, and is friendly with everyone, but is especially bonded to the daughter.
Pit-bulls kinda scare me, because I have heard that sometimes even a good one can develop a brain problem in there last years and suddenly attack anyone including there owners.
For now it is a big clumsy somewhat shy dog that gets along with everyone, but as I said I am somewhat concerned about what could happen when it gets old.
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Putting down a pet is hard. I've had to do that in the past with a good dog named Tasha, and once with a good cat.