Inflammation or infection surrounding the eyes.

Clinical Signs

May see any of the following:

  • Excessive blinking, and porphyrin/tearing (rust red stains) around the affected eye(s).
  • Crust formation at or around eye(s) from inflammatory drainage.
  • May see swelling of the lid or around the eye(s) and redness to tissue of the eye(s) when the lower lid of the eye is gently pulled down.


Conjunctivitis in rats may be caused by bacterial infections (e.g., Pasteurella pneumotropica, and Streptococcus pneumonia), or viral infections such as SDAV (sialodacryoadenitis). It can also be due to environmental irritants such as high concentrations of ammonia from urine in cages, dust and chemicals found in certain litters, from disinfectants or detergent residues following cage cleaning, or placing cages in areas of the house where owners may smoke. Another cause that contributes to conjunctivitis is self-trauma to the eyes from persistent scratching or rubbing.
In addition, rat’s that are elderly, or having decreased resistance to infections, are also at risk for developing conjunctivitis.

Inflammation and infection can at times begin in one eye, and be quickly transferred to the other eye by way of contamination through grooming or cleaning.

How severe the condition is will depend upon the overall health condition of the rat, and the agent that is irritating to the mucous membrane that lines the eye and eyelid. Persistent contact with the irritant involved sets up the inflammatory response, and if left untreated or continues to spread to the cornea of the eye causing keratitis, can result in the cornea becoming cloudy, or appear to have a bluish tinge, or in severe cases ulcerate.

The onset of conjunctivitis is acute and treatable. It can, however, reoccur if the underlying cause is not able to be determined or corrected.

The condition does not appear to be either zoonotic (infected animal giving disease to human) nor zooanthroponotic (infected human giving disease to animal). However, it is still important when giving care to a rat with conjunctivitis to wash hands before caring for the affected rat, and before caring for another rat in order to prevent the spread of infection.

For other conditions associated with conjunctivitis, see uveitis , and glaucoma.


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

Smears and cultures may be obtained to determine if the cause is bacterial or viral.


May gently irrigate eye(s) with sterile saline if discharge or crusting is present.
*Note: sterile saline for contact lens eye wearers (not the cleaning solution) or natural tears (OTC), without preservatives added, may be used to irrigate with if name brand normal saline eye irrigating solution is not available.

May apply warm compresses to eye 5 to 10 minutes, 2 to 3 times a day, if inflammation is present.

If the rat is scratching the eye, apply cool compresses to help with the relief of itching.

Apply topical ophthalmic antibiotic ointment or drops as directed by a veterinarian.

If inflammation is present, or the suspected cause is due to an allergen, then apply topical ophthalmic antibiotic ointment or drops that include a steroid such as hydrocortisone or dexamethasone.

*Note*  ophthalmic ointments, or ophthalmic drops, which include steroids should not be used in the presence of abscesses, corneal abrasion, or corneal ulceration.

If an abscess is present, it should be opened and drained.

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 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 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.
  • If condition does not improve or becomes worse notify your veterinarian.


  • Inflammation and drainage resolves
  • Eye(s) appear normal


  • Keep the cage environment clean.
  • Rinse cage(s) well following use of disinfectants or cleaning solutions.
  • Keep housing environment in a draft free area.
  • Use dust free litters.
  • Do not smoke in or around where rats are housed.
  • Treat all respiratory illnesses promptly.


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