2.1. Samples collection
One hundred seventy-three samples were collected from cats under one year of age from 15 catteries and six veterinary hospitals in southwest China from 2017 to 2020, of which 93 samples were from catteries, and 80 samples were from veterinary hospitals. Of the 173 samples, 150 fecal samples were obtained from cats with diarrhea, and 23 samples of ascetic fluid were obtained from FIP-suspected cats. The cattery samples were collected from pet breeding centers and stray animal shelters in southwest China, both considered multi-cat environments. The samples collected at the veterinary hospital were individual, home-owned pets considered to come from single-cat environments. The cat breeds included British Shorthair, Nulla luctus felis, Ragdoll, Garfield, and Persian. The samples were shipped on drikold and stored at –80 °C.