Bobi the dog made global headlines earlier in October when it died at age 31 – the oldest on record.
However, the Guinness World Records said it is investigating if the dog from Leiria, Portugal, truly lived to 31 years and 165 days, according to a report by The Guardian on Sunday.
This comes as veterinarians question if it is biologically possible for a dog to live for the equivalent of 200 human years, said the report.
Bobi was registered in 1992 with the Veterinary Medical Service of the Municipality of Leiria, which confirmed its birthdate.
Although the dog’s age was registered in the national pet database, such a process is usually based on owners’ self-certification.
Bobi was a pure-bred Rafeiro do Alentejo, a Portuguese breed of livestock guardian dogs with an average life expectancy of 12 to 14 years.
There has also been scrutiny online over Bobi’s images in 1999, which show that he has different coloured paws, unlike the dog which died on Oct 21.
A Guinness World Records spokesperson told the news outlet: “We’re aware of the questions around Bobi’s age and are looking into them.”
Dr Danny Chambers, veterinarian and council member of the United Kingdom’s Royal College of Veterinary Surgeons, said that of the 18,000 members of the Veterinary Voices group he runs, “not a single one of my veterinary colleagues believe Bobi was actually 31 years old”.
“This is the equivalent of a human living to over 200 years old, which, given our current medical capabilities, is completely implausible,” he was quoted by The Guardian as saying.
“Extraordinary claims require extraordinary evidence, and no concrete evidence has been provided to prove his age.
“We are a science-based profession, so for the Guinness Book of Records to maintain their credibility and authority in the eyes of the veterinary profession, they really need to publish some irrefutable evidence,” he added.
