Eye injuries can progress quickly. Urgent evaluation is recommended if your pet develops squinting, redness, and yellow-green discharge. In some cases, these symptoms indicate the presence of a corneal ulcer. While simple ulcers are often managed by your family veterinarian, more complicated cases may require referral to a board-certified veterinary ophthalmologist. Here’s a breakdown of what pet parents need to know about corneal ulcers in their dog or cat, as well as what to expect for treatment.
The Three Layers of the Cornea
First, let’s review the anatomy of the cornea! The cornea is the clear outer surface of the eye. It is composed of the following three layers which focus light and protect the eye:
- Epithelium Layer
- The outermost layer of the cornea provides a barrier to protect the eye and support the tear film.
- Stroma Layer
- The thickest layer of the cornea is made of collagen which provides support and strength to the cornea.
- Endothelium Layer
- The deepest layer of the cornea has fluid pumps which remove fluid from the stroma to keep the cornea dehydrated and clear.
Deep corneal ulcers often result in more redness, discomfort, and a visible defect. Bacterial infection is commonly associated with this corneal ulcer appearance.
So, what exactly is a corneal ulcer?
A superficial corneal ulcer is a break in the outermost epithelium layer. Most pets recover quickly from this type of ulcer, but some can become complicated and may require a surgical procedure to encourage healing. If an ulcer becomes infected, however, formation of a deep ulcer can result very quickly. Emergency evaluation of the eye is recommended if a divot is seen on the surface of the eye.
What causes corneal ulcers?
Corneal ulcers can form due to many causes, including, but not limited to:
- Trauma
- Irritating chemicals
- Inward rolling of the eyelid (entropion)
- Abnormal hairs (ectopic cilia or distichia)
- Dry eye
- Infection (Feline Herpesvirus)
A superficial corneal ulcer is more easily seen with fluorescein stain.
Symptoms
Corneal ulcers are painful! Here are the most common symptoms pet parents may notice:
- Squinting
- Pawing
- Rubbing at eye
- Redness
- Tearing
- Green-yellow ocular discharge
Note that superficial corneal ulcers are difficult to see without magnification. They are often easier to see via application of a fluorescein dye which adheres to the site of a corneal ulcer and appears bright green under a black light.
Deeper corneal ulcers can sometimes appear as a visible divot in the cornea.
How is a corneal ulcer treated?
Superficial corneal ulcers often heal within 7-10 days depending on the size and cause. Topical antibiotic drops and oral pain medications are used to reduce the risk of infection and improve comfort while the ulcer heals. Rigid protective Elizabethan collars (E-collar/cone) are recommended to protect the eye and prevent self-trauma which can delay and complicate healing.
Superficial ulcers that have not healed within 7-10 days may be caused by a persistent irritant, inward rolling of the eyelid, or an underlying healing defect. Surgery to remove barriers to healing may be necessary. Deep corneal ulcers require aggressive treatment to prevent progression. Medical management of an infected corneal ulcer includes frequent application of eye drops, pain medications, and sometimes antibiotics by mouth. In severe cases, a corneal surgery is needed to stabilize the cornea and prevent eye loss.
The quick identification of any eye pain as well as corneal ulcer formation is critical to the prevention of severe eye disease. Brachycephalic breeds (such as Pugs, Shih Tzu, Pekingese, etc.) are at increased risk for corneal ulcers; however, any pet should be evaluated by a veterinarian immediately if tearing and blinking progresses to severe squinting with green-yellow discharge. At Animal Emergency & Referral Center of Minnesota, our Ophthalmology Service is equipped to diagnose, triage, and care for your pets should a corneal ulcer occur. If you have any questions or concerns about your pet’s corneal ulcer or other eye health topics, ask your family veterinarian for a referral today.
