Mrs. T, a close friend of ours, Aikidomayland's 2nd mom, was in the hospital a little while ago. She has a large ridgeback dog, named Suzy, who is her guard dog and companion. Suzy doesn't normally bark unless she is given cause, a stranger coming into the driveway, a rat in the back yard. She is kept in her enclosed back yard.
While Mrs T was in the hospital, Suzy barked a few times. Probably stress related, and the person taking care of Mrs T's house did her best to quiet Suzy. The neighbor behind her complained, and the situation was explained to him. That Mrs T never allows Suzy to just bark and bark. (And she doesn't)
He said "%#%$#^ thing should be poisoned, that would shut it up."
A few days later, Suzy is deathly ill, vomiting, staggering and falling, losing weight rapidly. Taken to the vet, it was determined she ingested something toxic, and her symptoms were treated empirically. It took a few days, but she did recover, and now is in the process of gaining weight and getting her strength back.
There is no proof the bastard living behind her poisoned her, but Mrs T is scrupulous about Suzy and her care. And there is no way her house sitter did it.