Eye Infections


Eye ailments that are caused by bacterial, viral, or other microbial agents.

Clinical Signs

May see any of the following involving the eye:

  • Redness
  • Scratching of the eye by the rat
  • Squinting
  • Swelling
  • Signs of Pain (*Note: for information on recognizing various signs of pain or discomfort refer to: Signs of Pain In Rats).
  • Mucopurulent discharge (thick white, yellow, sticky, crusty) covering globe of eye
  • Porphyrin staining (rust colored tears) around the eye

More serious signs that may accompany infection of the eye(s) for which immediate veterinary assessment should be sought:

  • Bulging of the eye(s)
  • Facial swelling around the eye(s)
  • Signs of respiratory infection (nasal drainage, breathing issues: labored, rapid, gasping, and wheezing).
  • Head tilt or ear drainage


Eye infections can be caused by several agents such as: bacterial, viral, fungal, or parasites. In some cases, allergic response can cause signs similar to infection. Infection can involve the eye itself and/or the tissue surrounding the eye. Serious infections of the eye(s) that involve the deeper, interior, portions of the eye can result in loss of sight.
Infection may be unilateral or bilateral meaning involving one or both eyes, or if the infection began in one eye it may spread to the other eye.

Some types of eye infections are:

  • Conjunctivitis: inflammation involving the conjunctiva membrane, covering the eye whites and inner eyelid parts.
  • Blepharitis: an inflammation involving the eyelids.
  • Keratitis: an inflammation involving the cornea.
  • Keratoconjunctivitis: an inflammation of both the cornea and conjunctiva.
  • Uveitis: an inflammation of the uveal tract of the eye consisting of the iris, ciliary body, or choroid. It may also originate in the retina.
  • Dacryocystitis: an inflammation of the lacrimal sac.
  • Harderian gland infection.
  • Endophthalmitis (bacterial): an infection within the orb.

Eye infections in rats are typically related to bacteria. Many types of bacteria are naturally found on the body, or in the environment, and cause no health issues to the animal. However, once they gain access into the eye these bacteria can create serious infections. Often the bacteria are introduced by irritation, an abrasion, or by an injury to the eye. Neoplastic or hyperplastic glands, or masse, behind the globe can cause the eye to bulge which make the globe more susceptible to infection. Eye infections can also occur when a rat is exposed to an infected cage mate, or even humans, or by way of contaminated fomites.

Viruses, particularly RCV (also known as SDAV or Rat Corona Virus), can cause excessive dryness, overproduction of Harderian gland secretions, and ulcerations of the eyes. This can leave the eyes highly susceptible to secondary bacterial eye infections even after the virus has resolved.

Bacterial, or fungal eye infections, or eye infections resulting from parasites often require treatment with an appropriate antimicrobial ointment, solution, or in some cases a systemic agent. Eye infections can become a serious health issue for the rat and can result in blindness or even death if not treated appropriately. It is recommended that any rat showing severe or persistent clinical signs of an eye infection be immediately assessed by a veterinarian.

Keeping the rat’s environment clean, treating rats that may be ill, and practicing good hygiene by washing hands before and after caring for pet rats will reduce the chance of, or decrease the severity of infection.


Case History and Photos

  • Fig. 1: Left eye infection in female rat (Ellie)
  • Fig. 2: Left eye infection in 18-month-old female rat (Maya)


Obtain history, type of environment, exposure to any new arrival of rats into the home.

Do External examination of the eye.

Use of ophthalmoscope to view eye surface, anterior chamber, vitreous, and retina

Fluorescein staining with Wood’s visualization can help detect a breach to the cornea

Smears and cultures may be of help in determining causative organism.


Viral eye infections and very mild bacterial infections may resolve on their own. Often, home-care measures and over-the-counter medications may help to manage the rat’s symptoms.

Treatments may include the following:

  • To relieve itching, swelling or pain, apply cool damp compresses to the affected eye for 5 to 10 minutes, 2 to 3 times a day. Dispose of the compress in the trash, following each use, to prevent the spread of infection from one eye to the other.
  • To remove porphyrin, drainage or crusting around the eye, apply warm damp compresses to eye for 5 to 10 minutes, 2 to 3 times a day. Dispose of the compress in the trash, following each use, to prevent the spread of infection from one eye to the other.
  • Gentle irrigation with a normal saline eye irrigating solution, or instillation of preservative-free Natural or artificial tears (OTC) may help to soothe the rat’s eye(s).

For more serious or persistent infections, ophthalmic antimicrobial ointment or drops, or systemic antimicrobials may be prescribed by the veterinarian.
For information pertaining to medications refer to the Rat Medication Guide.

For more information specific to types of eye conditions refer to the section on: “Eyes” in the Health Guide section of Rat Guide.

Nursing Care

  • Always wash hands before and after cleaning to prevent spreading the infection to your rat’s unaffected eye, or to other rats in the household.
  • When using an irrigating solution to clean eye(s), be sure to irrigate from inner aspect of eye (near nose) to outer portion of affected eye(s).
  • If only one eye is involved prevent drainage from the affected eye contaminating the unaffected eye.
  • When cleaning eyes with a cloth, do not use a back-and-forth cleaning motion across eye, but clean from inner aspect of eye (near nose) to the outer portion of the eye to prevent reintroducing infection.
  • Use disposable cloths to clean eyes, or wash used cloths after each use.
  • Use medications as prescribed and for length of time prescribed.
  • When required to apply eye ointments, or eye drops, wash your hands first. Then gently wipe the rat’s eye with a clean, warm, damp cloth from inner aspect of eye (near nose) to outside portion of eye to remove crust and or porphyrin. Do not wipe back and forth. If more cleaning is needed use another untouched area of the cloth.
    • Next, remove cap from ointment or drops & lay cap on a clean cloth or paper towel. Do not touch tip of tube with your fingers or have tube itself touch eye when applying the medication.
    • For eye drops gently open eyelid and squeeze number of drops prescribed to the eye and gently hold eyelid closed for a second.
    • For eye ointment application, open eyelid gently and squeeze a thin ribbon of ointment from tube along the inside (as best you can) of bottom lid from inner aspect of eye (near nose) to outside corner. Do not be concerned if you end up running the thin ribbon of ointment across middle of eye, in the event it becomes difficult to hold the rat still. It’s fine. Once the ointment has been placed, close and gently hold eyelid closed for a second or two. The warmth & movement of the eye behind the closed lid will help melt and disperse the ointment over the globe.
  • If condition does not improve, or becomes worse, notify veterinarian.


  • Pain relieved
  • Loss of sight prevented or minimized
  • Inflammation and drainage resolved
  • Infection resolved
  • Eye(s) appearance normal


  • Keep the cage environment clean.
  • Rinse cage(s) well following use of disinfectants or cleaning solutions.
  • Keep housing environment in draft free area.
  • Use dust free litters.
  • Do not smoke in or around where rats are housed.
  • Treat all respiratory illnesses promptly.
  • Follow quarantine methods for protecting pet rats. See information regarding quarantine refer to the article “Quarantine” in the Health Guide Basics section of Rat Guide.


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