When Corey Dixon left his cardiac service dog, Aspen, at a Toronto PetSmart before taking off for a trip to the Muskoka region, he thought he was giving her a break.

But now, he says he shouldn't have done it.

"I was expecting a little vacation for her because she's working most of the time for myself," Dixon told CBC Toronto. "I thought one week shouldn't be a big deal."

But when he returned on July 8, Aspen was "extremely sick" and needed a vet.

"Now I'm going even longer without her," said Dixon, 23, who has a heart condition and needs Aspen's help to alert passersby when he faints in public. He had been wary of taking her into cottage country, and, with so few people around, wasn't sure she'd be much help even if he needed it.

Dixon says Aspen was shaking in a pool of her own vomit and saliva when he picked her up at the PetSmart in north Etobicoke.

"She stumbled over to me and collapsed in my arms."

He pressed the employees to tell him what happened but, he says, they eventually told him he needed to take the matter to the company's corporate head office.

"My reaction was very upsetting to say the least," he said.

Corey Dixon said that Aspen, a four-year-old black Labrador Retriever, saved his life multiple times in the relatively short time they were together. (@CoreyDixon33/Twitter)

Dixon took Aspen to an emergency vet. They found she'd lost nearly 20 pounds and was suffering from mild dehydration and high blood pressure.

A medical document provided by The Collegeway Animal Hospital said the underlying cause "is not known, but can range from something simple like gastroenteritis" or a "systemic illness/infection" to a toxin or foreign object she might have eaten, "like her bedding."

Photos Dixon took of Aspen's kennel suggest she ate her bedding.

"She continued to eat the bed and they didn't bother to take it out," he said.

Photos Dixon took of her kennel suggest Aspen had eaten her bedding. (Corey Dixon)

PetSmart's website says the company offers "full-service accommodations" with "24/7 onsite care" and an "on-call veterinarian."

But Dixon alleges there was no vet, which was also part of the agreement he signed.

Dixon says the company is reimbursing him for Aspen's stay and veterinary bills, which add up to more than $1,000.

PetSmart says it is investigating.

"But our initial findings indicate that our associates followed all policies and procedures," said spokesperson Erin Gray, in an email to CBC Toronto.

"Additionally, we have asked [Dixon] to provide veterinary records so we can better understand the root cause of Aspen's illness."

Dixon was back at the emergency vet on Thursday, awaiting more information about Aspen's condition.

"She's still pretty sick," he said.

"She's more than just an animal to me," he said. "She's my service dog and a huge part of the family."