Police in Delta, B.C. are investigating the sudden and mysterious death of an otherwise healthy family dog whose owner claims it was intentionally poisoned last week.

June Mark said she was getting ready to take her three-year-old Bernese mountain dog, Kleo, for a walk Wednesday when the dog ran into the house and started vomiting chunks of hotdog.

"I didn't think anything of it. I just cleaned it up," June said. "I thought my sister had just fed her a bunch of hotdogs."

But the pup's condition only worsened over the next four days. Kleo had a seizure on Thursday and then two more on Friday before June took her to the vet.

"She was staggering, falling over, walking into walls, foaming at the mouth," she told CTV News Tuesday.

After being given little hope of the ailing dog surviving, June was forced to say goodbye to her best friend Saturday.

"You can't even explain how hard it is to make that choice," she said, describing the dog, who had been rescued from a Langley puppy mill as "the love of my life."

June said she doesn't know who might be responsible, but is convinced the hotdogs Kleo ate before being ill were laced with anti-freeze and deliberately placed in her yard.

"It's sick is what it is," she said, adding that the vet also said agreed that poisoning was a likely cause of the dog's death.

"It didn't seem to fit any regular kidney disease or anything else that could have hit her that hard, that fast," she said. "I've seen animals that are poisoned before, so my mind went straight to the poison."

Now, June said she's speaking out about the incident as a warning to other pet owners.

She's also concerned because her yard is steps away from a school playground and a child could have eaten the tainted food, including the young kids next door or even her own grandchild.

June said she'd received two anonymous complaints last summer about barking, but there's nothing to link them to what happened to Kleo.

Delta police are investigating the incident, but animal cruelty officials say it's unlikely to dog owner will ever get the closure she's after.

"We've investigated many of these in the past. Unfortunately, very few tend to lead to the culprit," said Marcie Moriarty, the BC SPCA chief prevention and enforcement officer.

Even with a toxicology report or samples the tainted food poisoning is difficult to prove, Moriarty added.

June said she didn't want to pay "hundreds of dollars" for toxicology tests because the vet told her she was unlikely to get a definitive answer.

Under the Criminal Code, those convicted of poisoning a domestic animal could face a five-year prison sentence and could be charged under the Prevention of Cruelty to Animals Act.

While CTV was at June's home on Tuesday, officers arrived to take a statement, photos and canvass the neighbourhood for information.

In the meantime, all June can do is try to adjust to life without her 100-pound cuddle bug.

"You come in the door, she was wagging from head to toe," she said. "I come in the door now and it's just nothing."

With files from CTV Vancouver's David Molko