The boy already had a female rat and bought the male rat to keep her company.
After the brand new rodent bit the boy, he began having stomach pains.
“I put him to bed after a day at the doctor’s office and the next thing I knew it just was too late,” his grandmother told ABC News.
Her nightmare continued. ”I went into his room, and he couldn’t speak. He was unstable on his feet. I got him down to my room and he collapsed on the floor. I called 911 because it was scaring me that his breathing was shallow and he seemed to be losing his ability to function.”
Aiden Pankey was rushed to a hospital where he died from rat bite fever a few hours later.
The tragedy happened last summer, but his parents waited for proof the rat was infected before filing suit against Petco. The lawsuit claims the store didn’t have stringent enough procedures to prevent such an incident.
Petco has only said they are "in the process of investigating these claims and will respond appropriately when we have more information."
A check of record shows just a few hundred cases of rat bite fever have been confirmed in the US. Doctors think there may be more cases but believe the condition is underdiagnosed.
They warn there may be a big spike in the illness due to the uptick in the number of rats now kept as pets.