Red Eye in Cats

If you notice redness of the feline’s orbit, she might have experienced trauma to the eye, an allergy or irritant, a viral infection such as distemper, a bacterial infection, glaucoma, cherry eye or cancer. Red eye in cats could be a serious medical problem that could worsen over time, causing blindness and further destruction of the orbital structure.

Red eye in cats is a symptom of an underlying disease, ocular irritation, or injury to a feline’s eyes. A red coloration of one or both eyes is an indication that a feline is suffering from an unknown health condition that should be addressed by a licensed veterinary professional.

The rather obvious symptom of red eye in cats is, in fact, a red coloration of the eye. Depending on the source of the red eye condition, your feline may or may not experience the following additional associated symptoms: 

• The whites of the eyes become reddened 
• Swollen eyes
• Swollen eyelids 
• Eye discharge (clear, white, yellow or green in coloration) 
• Tearing of the eyes
• A protruded third eyelid (cherry eye)
• Rubbing the eyes
• Itchy eyes
• Inability to open the eye
• Loss of sight 
• Sneezing
• Watery eyes 
• Coughing 
• Painful eyes

A feline’s eyes can become red for a number of reasons. Trauma, allergies, obstructions, structural changes of the eye, disease, viral infections, bacterial infections, and irritants can all cause the eye of a cat to become red. The most common causes of red eye in cat include: 

Trauma

• Scratches
• Bites
• Pokes
• Allergens
• Pollen
• Dust
• Bee stings

Irritants

• Cigarette smoke
• Perfumes
• Air fresheners 

Obstructions

• Seedling
• Grass seeds
• Dirt 

Structural Changes

• Entropion (eyelid protrudes inward) 
• Ectropion (eyelid protrudes outward)
• Distichiasis (abnormal eyelash growth)

Disease 

• Cancer 
• Autoimmune disease

Bacterial Infection

• Chlamydia
• Mycoplasma

Viral Infections

• Feline herpesvirus type 1
• Calicivirus
• Feline immunodeficiency virus (FIV) 
• Feline leukemia (FeLV)

It is highly important for pet owners to relay all the clinical signs and symptoms they noted at home as they bring the cat experiencing red eye to see the veterinarian. Since red eye in cats can be caused by a long list of potential causes, any information you can give the veterinarian to help create a diagnostic differential would be helpful. The doctor will begin by reviewing the cat’s medical record, playing close attention to past illnesses, medications, and vaccinations. He or she may ask to know about your cat’s living environment, including any possible allergens, irritants, or potential trauma tools in the feline’s surroundings. 

An Ophthalmic Exam

A physical exam of the eye will be the next step in the veterinarian’s diagnostic plan, as the examination will evaluate the eye and all the ocular structures. The animal doctor will likely use a tool called an ophthalmoscope, which is a light reflecting tool that will allow the vet to see the interior structures of the eye. 

Fluorescent Stain Test

An ophthalmic examination tool that uses blue light and orange-colored dye may be used to detect abnormalities within the eye. 

Schirmer Tear Test

An ophthalmic tests uses tear strips that are placed in the lower eyelid to evaluate a feline’s tear production levels. 

Tonometry

An ophthalmic test used to evaluate intraocular pressure of the eye. 

Lab Tests

The veterinarian may also collection a swab of cells or discharge from the eye for microscopic examination. The collected cells could reveal structural abnormalities or an infection from a bacteria. Blood work, a urinalysis and specialized testing for FeLV, or FIV will likely be a part of your cat’s differential diagnostic procedure. 

The treatment of red eye in cats depends on the condition that is causing your cat’s eye to turn a reddish color. If allergies or irritants are to blame for your cat’s red eye, the doctor may advise a few simple changes at home and prescribe an antihistamine. However, if the cause of your cat’s red eye is caused by a structural abnormality, foreign obstruction, trauma or growth, a surgical procedure may need to be completed to restore your feline’s eyes to their original state. Chemotherapy drugs and radiation therapy could also be a part of your cat’s treatment plan if cancer is the source of your cat’s red eyes. 

The prognosis for red eye in cats depends on the dominant cause of the ocular reddening in your cat. Your cat may need to wear an Elizabethan collar at home to prevent scratching the eyes and causing additional damage. The veterinarian may also ask that an air humidifier be placed in the home to remove irritants that may be affecting the feline.