Eye Discharge

  • Some pets produce more tears than others, so increased wetness of the eye is not always a medical problem.
  • Eye discharge becomes a problem when it is excessive, abnormal, or accompanied by other signs of a problem (such as squinting, rubbing, or sneezing).
  • Depending on the cause of the eye discharge, drops or ointments applied directly to the eye are effective in many cases.

What Is Eye Discharge?

Eye discharge can refer to any type of fluid that comes from the eye. Most healthy pets have eyes that are clear, bright, and have minimal discharge. However, some types of eye discharge are completely normal. Each time your pet blinks, tears are released from tear ducts and bathe the surface of the eye to provide moisture and deliver oxygen and nutrients. Some pets produce more tears than others, so increased wetness of the eye is not always a medical problem. Some pets can also have crusty material at the corners of their eyes when they wake up. This is usually easy to clean with a damp tissue and is not considered a problem in most cases.

Tear staining occurs in some dogs and cats. Animal tears contain components that can cause brown staining of the fur around the eyes. In pets with light-colored fur, this discoloration can be more noticeable than in pets with darker fur. Tear staining is not generally considered a medical problem, but can sometimes be minimized by keeping the facial fur trimmed close and wiping the eyes daily with a damp tissue to remove excess material. If tear staining is excessive, ask your veterinarian about other management options.

When Is Eye Discharge a Problem?

Eye discharge becomes a problem when it is excessive, abnormal, or accompanied by other signs of a problem. A small amount of clear discharge can be considered normal, but excessive tearing or consistent watering should be investigated. Normally, tears produced around the eyes drain out of the nose, through the nasolacrimal ducts. Occasionally, these ducts can become blocked, causing the clear discharge to spill out onto the face.

Similarly, discharge that becomes thick or starts to look like mucus or pus can indicate an eye infection or other problem. Even if eye discharge does not seem excessive or abnormal, if it is accompanied by other clinical signs such as squinting, sneezing, or rubbing the eyes with a paw or against other objects (such as furniture or the floor) this can indicate an eye infection or other problem. Eye discharge can also occur with some systemic illnesses (illnesses that affect the entire body), such as an upper respiratory tract infection.  

Dogs and cats that have short, flat noses or “pushed in” faces, like Persian cats and Pekingese dogs, sometimes have folds of skin on their faces (right under the eyes) that become moist and infected from being consistently wet from tears. Also, the hair on their faces sometimes brushes the surface of the eyes, scraping against the cornea (the clear covering of the surface of the eye) and causing irritation and increased eye discharge.

Dry eye is a condition in which tear production is too low to keep the surface of the eye moist. Instead of tears bathing the cornea with each blink, the inner eyelids scrape against the cornea, causing trauma and irritation. Pets with dry eye tend to develop a thick white or green discharge from the eyes in response to the cornea becoming excessively dry and irritated. These pets may also squint or rub their eyes because dry eye can be painful.

Irritating airborne substances can cause redness, excessive watering, and other problems with the eyes. Common airborne irritants include cigarette smoke, dust, dirt, pollen, and sprays/perfumes used around the home.

How Is Eye Discharge Diagnosed?

Medical history and physical examination findings can provide valuable information for your veterinarian. Medical history may include trying to determine how long the eye discharge has been present and whether any other signs of illness have been observed. Physical examination findings may reveal evidence of underlying illness.

If the pet is squinting because the eyes are painful, your veterinarian may begin the eye examination by applying a drop of liquid topical anesthetic directly to the eye. This is not painful, and after a few minutes it makes the surface of the eye numb so examination can proceed. During examination, your veterinarian will likely look for redness, puffiness, foreign bodies, wounds, or other changes that may explain the eye discharge.

While examining your pet’s eyes, your veterinarian may also perform tests to make sure your pet’s tear production is adequate, to check the cornea for scratches or other injuries, and to determine if the nasolacrimal ducts are blocked.

How Is Eye Discharge Treated?

If your pet has an infection or inflammation involving the eyes, drops or ointments applied directly to the eyes are effective in most cases. If tear production is inadequate (as with dry eye), long-term medication may be recommended to control the problem.  If the nasolacrimal ducts are blocked, flushing them with sterile eyewash may help clear any obstructions.

Certain grooming practices, such as keeping the hair on the face trimmed closer, can help reduce tear staining and minimize contact of facial hair for dogs and cats that have flat faces. 

If your pet does not tolerate dust, cigarette smoke, and other airborne irritants, your veterinarian can help you devise a plan for reducing these irritants around your home.