Why did police shoot PTSD service dog?

There is something that does not make sense in this report. The training these dogs get also comes with a personality check to make sure they are not aggressive. Having an aggressive dog would not help a veterans being treated for PTSD. So how is it this dog turned "vicious" all of a sudden?

Police shoot, injure service dog
9News.com
Nick McGurk
May 7, 2013

DACONO - A Dacono man, who says he suffers from PTSD after multiple tours of duty in the Marine Corps, is upset after police shot his service dog Sunday night.

"I was right here in the grass. He probably just got curious and wandered out there," said James Vester, who says his service dog of three years escaped out through an open fence at his home.

Minutes later, Vester heard a gunshot.

"Blood was coming out of his chest," Vester said.

He said he saw his dog Mongo trailing blood as he returned to him. Mongo had gone down the street and around the corner when police received word of a loose dog.

"The information they received from dispatch was a vicious aggressive dog that did not belong to the owner, at her house, up on her property, jumping on her fence, growling and bearing its teeth," Dacono Police Chief Brian Skaggs said.
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