Cruz, a Samoyed, died on Feb. 16 in Colorado, days after the Westminster Kennel Club Dog Show, The New York Times reported Wednesday.
Although a necropsy was not performed, Molly Comiskey, the Colorado veterinarian who treated Cruz, said the dog showed symptoms that strongly resembled those of dogs that had ingested rodent poison, adding that she felt it was unlikely that Cruz had been deliberately poisoned.
"Dogs are dogs. It's not anyone's fault. They eat stuff; they get into things; they make bad decisions," Comiskey said.
Robert Chaffin, Cruz's handler, said he believed that extreme animal rights activists, might have been responsible. Animal rights activists have called dog shows and purebred competitions inhumane
"Unfortunately, dog shows have been plagued by some of these people for years," Chaffin said. "I've heard horror stories about other people's dogs having their setups tampered with, being poisoned, but I never thought it would come to me."
"It would have been easy for someone to throw something in [Cruz's] cage," Chaffin said.
However, Chaffin added that he had uncovered no evidence that Cruz had been deliberately poisoned, and he acknowledged that it was possible that the dog had accidentally swallowed poison.
The founder and president of People for the Ethical Treatment of Animals, Ingrid Newkirk, said that her organization has sent members to the Westminster dog show in protest and to distribute leaflets near the venue. She also said that her organization had nothing to do with Cruz's death.
"PETA does not sanction that," she said. "It's so scurrilous; it's so low to even suggest it."
2014: The Year in Music [PHOTOS]