Blaine Cowick of the 500 block of Blackbird Drive said the grisly discovery was made by his 14-year-old son James, a freshman at Amador Valley High.
The teen arrived home but wasn't greeted with Jazz's usual barking. Looking out a window, he spotted the two pit bulls.
"He didn't see our dog, so he ran around to our neighbor's yard and climbed the fence," Cowick said. "He saw our dog and there was blood everywhere. It kind of looked like a murder scene."
He said James called 911 and police quickly responded. By the time his wife came home, police and animal control were there
Cowick said his neighbors, who live nearby on Crestline Road, had a history of people calling the police on them due to the dogs, sometimes leaving them outdoors while they were away for the weekend. He said the dogs escaped through a small gate between the two homes.
"I'm sure they heard my dog barking, they just dug and busted right through the fence," Cowick said. "I heard these dogs barking -- I had no idea they were pit bulls."
He said having the dogs is "akin to an automatic weapon."
"When they're in a pair -- there were two of them -- they get this pack mentality, they gang up and they kill," he said. "I don't want this to ever happen again. It could be a child."
In fact, he said, neighbors across the street run an infant daycare center, and another neighbor has a small child.
The owners voluntarily allowed their two dogs to be euthanized; had they opposed, Cowick said, the city attorney would had held a hearing to decide the dogs' fate.
He said his family got Jazz through Furry Friends Rescue, which is based out of San Francisco.
"They come out, they look at your yard, they make sure you have a fence, they make sure you have poisons locked away. We went through that whole process," he said.
Although it's normally not recommended, Cowick said he consulted others and decided to adopt a new dog right away.
"It's a little different from your dog just dying. It registered on the trauma scale," he said. "I thought it was best to get a puppy."
Coincidentally, Cowick said he'd seen a sign for border collie puppies in San Ramon the same day Jazz was killed.
"Normally, you want to give your kids a chance to grieve," he said. But on the day after the attack when the entire family took a day off to bury Jazz, Cowick said, "I lied, I kind of kidnapped them," and the family went to pick out its new puppy.
The death of Jazz has Cowick looking at the bigger picture, especially since James was upset for days after the attack.
"I know that pit bulls are responsible for two-thirds of the attacks on humans. Oftentimes, it is a family member or a close personal friend, so you don't hear about it," he said. "I think it's been swept under the rug and from what I can tell, it's kind of a growing problem.
Pit bull allies and foes are sharply divided on the dangers of the dogs.
Kristen Hart, Pleasanton's animal control services officer, said she's seen similar attacks before, and not necessarily by pit bulls. Hart worked in Fremont for nearly five years before coming to Pleasanton.
"I don't like to breed specify," Hart said. "There are some breeds that have a higher rate of 'prey drive,' or animal aggression."
She said in her experience, pit bulls can be triggered to attack in protecting their owners.
However, last year, a pit bull fatally mauled a pregnant Pacifica woman. An anti-pit bull website claims the dogs killed 52 Americans and accounted for 59% of all fatal attacks, although a site that supports pit bulls refutes those statements. Cowick questions the safety of the breed.
"One of the reasons I bought a house in Pleasanton is to have basic safety in my own yard. Shouldn't they have to post that they have something like that?" he said. "People -- it just seems that they're naive about what their dogs are capable of."