My cat has one pupil smaller than the other, with brown tears, and rhinotracheitis that improved on doxycycline and amoxicillin – what now?

A cat with one pupil larger than the other at night may be affected by light interference or genes; if pupils return to normal in daytime light with no other signs, there is usually no need to worry. Second, tearing has many causes – foreign-body irritation, bacterial or viral infection – and rhinotracheitis also causes tearing and red eyes; have a vet examine and confirm. Finally, after the rhinotracheitis improves, stop the doxycycline and amoxicillin-clavulanate, or use only amoxicillin, to avoid burdening the cat’s gut, liver and kidneys.