Our sweet little boy we adopted from the Humane Society 1.5 yrs. ago came home with us with horrible respiratory symptoms: red eyes, sneezing, visible mucus from his nose...we loved him anyway! Through 3 different rounds of antibiotics from the vets at the Society, he did not really improve much. Our personal vet then put him on the right antibiotic that helped him turn the corner finally, but also suggested Duralactin Lysine, to suppress the herpes virus that is one of the 2 main causes of respiratory infections in cats. It works well! He gets the beginnings of the symptoms all over again if we stop using it, so this keeps him healthy!