Buddy, a 7-year-old German shepherd from was the first dog to test positive for the coronavirus in the United States before he died on July 11 after a three-month illness.

Medical records reviewed for National Geographic by two veterinarians who were not involved in his treatment indicate that Buddy likely had lymphoma, a type of cancer, which would explain the symptoms he suffered just before his death.

"It's unclear whether cancer made him more susceptible to contracting the coronavirus, or if the virus made him ill, or if it was just a case of coincidental timing," the magazine reported.

The dog got sick in April and Mahoney suspected he had the virus, but it wasn't until mid-May that the family finally found a vet who would test him and who confirmed Buddy was infected.

"You tell people that your dog was positive, and they look at you (as if you have) ten heads," owner and Robert Mahoney's wife, Allison, told the magazine.