Conjunctivitis is an infection in the epithelium or mucous membrane of the eyelid (conjunctiva). The upper, lower and third eyelid all have conjunctiva associated with them. In a healthy cat the conjunctiva will not be visible, however, upon infection the conjunctiva will become red, inflamed, and swollen. The eye can have excessive tearing and discharge that will be clear to yellow, and the thickness of this liquid will vary from fairly runny to thick. As this condition persists the eyes can start to become crusty as the liquid hardens.

Conjunctivitis can be caused by an outside irritant (ie. an object getting lodged in the eye), by a trauma (ie. a scratch due to a fight), or by a bacterial or viral agent. The most common agents responsible for conjunctivitis include Chlamydia Psittaci and the Feline Herpesvirus (ocular herpes). The most common cause of reoccurring conjunctivitis that does not go away with typical antibiotic treatments is the Herpesvirus. For more information on the Herpesvirus and Ocular Herpes click here.

Conjunctivitis is treatable with proper medication but if left unchecked the infection can spread to the other eye, the respiratory tract, and other parts of the body. In extreme causes untreated conjunctivitis can also cause significant eye damage and/or blindness. Conjunctivitis is also contagious, so if you have other pets in the home they may also be at risk for developing conjunctivitis.

Conjunctivitis can also be a symptom of a more serious infection in the cat, thus, if you notice your cat with any of the symptoms below take him/her to the vet asap for an examination.

Symptoms to look for:

  • Tearing of the eye
  • Discharge from the eye
  • Redness and inflammation of the eye
  • Ulcers in the eye


Your vet can prescribe medication and/or treatment that will take care of the infection.

Precautionary measures:

Many kittens contract conjunctivitis due to contact with bacteria in the mother’s uterus. Although such conjunctivitis in kittens may be unavoidable, you can reduce the frequency of conjunctivitis in adults by keeping the cat indoors and in a clean environment.