Red eyes can be caused by many different things, particularly depending on which part of the eye is affected. Below is a list of common ailments that can cause the appearance of "red eyes". If you notice, many of them can cause similar symptoms so diagnostics and a thorough physical exam are critical to correct diagnosis and treatment.
Corneal Ulcer: The cornea is the front, clear part of the eye. We oftentimes refer to is as the "windshield" of the eye. Corneal ulcers are usually a result of trauma to the eye. Typical symptoms include redness of the sclera (the white part of the eye that usually is not visible unless you pull back the eyelid), squinting and tearing. In order to diagnose a corneal ulcer, a special stain needs to be done. Treatment typically includes a triple antibiotic eye drop or ointment that is made for the eye. We may also send home other medications, as these can be very painful. If you've ever had a hair or grain of sand in your eye then you can relate!
Glaucoma: Symptoms can be very similar to a corneal ulcer- redness of the sclera, tearing and squinting. As time passes, the globe can start to appear "swollen" but that takes a while to develop. Certain dog breeds tend to have "bulgy" eyes, such as pugs and some Chihuahuas. It is important to notice if there is a change to the eye. Some breeds are predisposed to glaucoma, such as Cocker Spaniels and Boston Terriers (as well as many others). We use a special instrument called a tonopen to measure the pressure inside the globe in order to diagnose glaucoma. Treatment is usually aggressive and should be instituted as soon as possible for best outcome. In spite of treatment, many cases may not respond and enucleation (removal of the eye) may be recommended to help keep the pet out of pain.
Abnormal bleeding into the eye: Pets can bleed into any part of the eye- the sclera, iris (colored part of the eye), and anterior chamber (the area between the iris and cornea) are the most common areas we can see this happen. When it happens in the anterior chamber, we call it hyphema. It most commonly is a result of trauma. However, low platelets (cells in our body that help blood clot formation) and/or clotting factors (decreased with rat bait poisoning or liver failure, in most cases) can also cause abnormal bleeding. A thorough exam and history is imperative! Blood work would be recommended in cases where there is no known trauma.
Keratoconjunctivitis sicca (KCS): This is a long word that basically means "dry eye". It is a result of inadequate tear production. We perform a Schirmer tear test to see if a pet is making enough tears. Symptoms usually include squinting, swelling and redness of the eye. We also usually see a thick, mucoid discharge. Some causes of KCS include immune-mediated adenitis (the body attacks the tear gland), neurogenic (the nerve to the tear gland is affected), or systemic disease (canine distemper). Breeds that are commonly affected are the Shih tzu and Lhasa Apso, among others. Treatment is aimed at the underlying cause as well as helping to increase tear production and keep the eye moist.
Conjunctivitis: The conjunctiva is the pink tissue that surrounds the globe of the eye. It can become red with allergies, irritation, trauma or abnormal bleeding. In some cases, it can be caused by other disease processes, such as glaucoma or KCS. Treatment is typically aimed at the underlying cause.
Ocular foreign body: Depending on where you live or your lifestyle, some pets will get a foreign body lodged in their conjunctiva. Most often it is a foxtail or grass awn. Symptoms usually include swelling, redness and tearing. In most cases a corneal ulcer develops secondary to the foreign body and the pet rubbing at their face. Treatment includes removal of the foreign body, controlling pain and specific treatment for the corneal ulcer.
If you notice any redness, eye discharge or squinting in your pet, treatment should be sought as soon as possible. Please call our office with any questions you may have or to schedule an appointment.