Hi,, I have 4 mother cats that had kittens in the same box... they are between 3 to 4 weeks old.. some were sick so we took them to the vet... They a had an eye and upper reporation infection .. we gave them the meds and cleaned there eyes. they are doing better. but now the are starting to dye. they are playing and then go a check on them and one past.. i've had three pass this week .