New allergies frequently pop up and their severities can change too – meaning Chloe has to keep track of them with a color-coded spreadsheet.

"While it's difficult to quantify how common these allergies are, many cases likely go unnoticed by the kitty's owner," a vet told Newsweek.

When a 20-year-old woman in the United Kingdom rushed to the hospital with a swollen face, hives spreading across her body, and difficulty breathing, doctors knew immediately what likely happened.