The main reason is that the cat herpes virus will consume arginine in the cat's body during the replication process. Studies have pointed out that supplementing lysine can compete with the herpes virus for arginine to reduce the number of viruses, but it also has the chance of reducing immunity. Therefore, PROUDPET launched an upgraded version of black yeast, which makes up for the deficiency of simply supplementing lysine in the past, and can further protect the cat's respiratory health.