Quote Originally Posted by smokey the elder View Post
This is going to sound odd, but have you had your water tested recently? Maybe there is some contaminant in your water supply which is causing the inflammation. One (expensive, but cheaper than going to the vet!) is buying several gallons of bottled water, and use that to water the cats for a few weeks.
Was thinking along the same lines. If their tests are all negative and they are indoor cats has something changed in their environment that could have brought it on? May not be contagious just something that they are all reacting to? Poor kitties (and Mom) - really hope the cause is found soon