By Jennifer Copley (Last Updated 12 December 2010)
Conjunctivitis (infection or inflammation of the conjunctiva), is the most common cause of eye discharge in pets. Conjunctivitis may be triggered by allergies or infections in other areas of the body (particularly upper respiratory and dental infections). Other causes of eye discharge include:
- Abnormal tear ducts that obstruct drainage
- Corneal inflammation (keratitis) or ulcer
- Disorders of the eyelashes
- Eyelid inflammation (blepharitis), abnormalities, or tumours
- Iris/blood vessel inflammation (uveitis)
- Irritant (foreign material in the eye or tear duct)
- Lens displacement (luxation)
- Long fur irritating the eyes (common in dogs such as the Pekingese)
- Prolapse of the third eyelid tear duct (“Cherry Eye”)
Eye problems should be treated as soon as they’re noticed because they can be a symptom of a life-threatening infection. Also, they may spread, eventually impairing vision, and some infections can be transmitted to other pets in the household.
How to Determine the Cause of Eye Discharge in Pets
The following are some questions you can answer to help your veterinarian make a diagnosis:
- Is the discharge clear and watery with no other symptoms? The problem may be the pet’s tearing mechanism or an allergic reaction.
- Is the discharge thick and green or yellow in colour? This suggests that there may be an infection.
- Is the problem seasonal, or does it occur after exposure to certain substances? The pet probably suffers from an allergy.
- Are the eyes red and itchy? Conjunctivitis is the most likely problem, particularly if the animal is pawing at the eyes or otherwise indicating that they’re itchy. Conjunctivitis often signals an additional infection, such as an upper respiratory infection.
- Is your pet a flat-faced breed such as a Persian or Himalayan cat or a Pug, Bulldog, Pekingese, Llasa Apso, or Shih Tzu dog? These breeds often have malformed tear ducts, which can cause chronic watery eye discharge.
- Has your pet suffered an eye scratch or other injury to the face recently?
- Does your pet go outdoors regularly? He may have gotten dirt, pollen, seeds, or other materials in his eyes.
- Has your pet been in contact with other animals recently at a cattery, kennel, animal shelter, dog park, or grooming salon? This increases the likelihood of infection.
- Is there flaking and crusting on the eyelids? The problem may be blepharitis.
- Are there signs of pain (squinting, blinking rapidly, avoiding light, pawing at the eyes, etc.)? There may be a foreign body or toxic chemicals (insecticides, shampoos, cleaning products, etc.) in the eye or an injury or ulcer of the eye, though glaucoma, uveitis, and other problems can also cause eye pain. When eye pain is present, the nictitating membrane (third eyelid) may cover part or all of the eye, though this may happen in response to other illnesses as well.
- Do the eyes appear cloudy? This suggests glaucoma, keratitis, or uveitis if there is also eye pain. If there is no pain, the problem is more likely cataracts.
- Is the eye bulging? This could be caused by tumours, abscesses, glaucoma, or having an eye out of its socket.
- Is there a red bulge in the corner of the eye? This suggests Cherry Eye, which most commonly afflicts dogs under one year of age, though cats occasionally suffer from this malady as well.
- Does your pet have very bad breath and suffer mouth pain, difficulty eating, and/or drooling? He probably has a dental infection.
- Does your pet suffer from additional symptoms such as lethargy, lack of appetite, coughing, noisy or open-mouth breathing, fever, weight loss, or sneezing/runny nose? This suggests a respiratory or other infection.
Treatment of Eye Discharge in Cats and Dogs
Treatment varies based on the cause of the discharge. In the case of infections, it may involve the use of antibiotics or other medications, which may be oral or topical (eye drops), depending on the nature of the infection. There are also medications available for extreme allergies.
Surgery may be required for severely malformed tear ducts or other deformities of the eye and tumours. Cherry Eye is usually treated by surgically putting the gland back in place.
As for home care, you can remove eye discharge by gently dabbing around the eye with a warm, moist cloth, but don’t rub or allow pets to rub their eyes, and never use eye drops developed for humans on pets. Consult a veterinarian before administering any other treatments.
How to Remove Substances from a Pet’s Eye
If there is a visible foreign body (dirt, grass, etc.) or chemical substance in the eye, Drs. Eldridge et al. (Cat Owner’s Home Veterinary Handbook) recommend flushing the eye for 10-15 minutes with cool water or sterile saline eyewash. This can be done by soaking a cotton ball in the liquid and squeezing it over the eye repeatedly.
If you are unable to remove the object or you successfully remove the object but your pet continues to paw at his eye, squint, or suffer eye discharge, consult a veterinarian. You should also consult a veterinarian after flushing chemicals from a pet’s eyes to make sure that there’s no permanent damage.
- Carlson, D., DVM, & Giffin, J.M., MD. (2008). “Causes of Watery Eyes in Cats.” Pets.WebMD.com.
- Eldredge, D.M.; Carlson, D.G.; Carlson, L.D.; & Giffin, J.M. (2008). Cat Owner’s Home Veterinary Handbook. Hoboken, NJ: Howell Book House.
- Eldredge, D.M.; DVM, Carlson, L.D., DVM; Carlson, D.G.; DVM, & Giffin, J.M., M.D. (2007). Dog Owner’s Home Veterinary Handbook. Hoboken, NJ: Howell Book House.
- Foster, R., DVM. (2010). “ Conjunctivitis (Red Eyes) in Dogs.” PetEducation.com.
- Glover, J., Dr. (n.d.). “Causes of Watery Eyes in Cats.” PetPeoplesPlace.com.
- Mar Vista Animal Medical Center. (2010). “Runny Eyes.” MarVistaVet.com.
- McNabb, N., Dr. (2010). “Ocular (Eye) Discharge in Cats.” PetPlace.com.
- Nash, H., DVM, MS. (2010). “ Red Eyes in Dogs and Cats.” PetEducation.com.
- Osborne, C., DVM. (2010). “Runny Eyes in Cats” and “Runny Eyes in Dogs.” DrCarol.com.
- Ruben, D., Dr. (2010). “Feline Upper Respiratory Tract Infections (URTI).” PetPlace.com.
- The Merck Veterinary Manual. (2008). “Opthalmology.” Whitehouse Station, NJ: Merck & Co., Inc.
- WebMD. (2007). “Watery Discharge in Dog’s Eyes.” PetsWebMD.com.