Keratitis in Dogs

There are different reasons the cornea may get inflamed such as injury, genetics, and bacterial or fungal infection. It is important to find the cause of the inflammation.  If keratitis is left untreated, it can lead to impaired vision and even blindness.

The cornea is made up of three layers of cells: the corneal epithelium (surface layer), the corneal stroma (middle layer) and the corneal endothelium (inner layer). The main function of the cornea is to retract light. It helps focus the entry of light into the eye and serves as a filter that protects against UV light from the sun. The cornea receives its nourishment from tears and the aqueous humor.

Some dog breeds develop keratitis more often than other breeds.  Dogs with short muzzles and prominent eyes (Pug, Boston Terrier, and Bulldog) are more susceptible to develop keratitis.

Keratitis in dogs is the inflammation of the cornea.  The cornea is the transparent dome that covers the eye’s pupil, iris, and anterior chamber. Keratitis is a painful condition, which can affect your dog’s vision.

In addition to inflammation of the cornea, the symptoms for each condition are:               

Fungal and Bacterial Infection Keratitis

• Eye redness
• Excessive tearing
• Eye discharge

Ulcerative Keratitis

• Squinting
• Pawing at eye
• Excessive tearing
• Sensitivity to light

 Chronic Superficial Keratitis 

• Whitish pink or brown discoloration on the cornea
• Third eyelid may thicken or change color
• Pigment infiltration into the cornea
• Blood vessel in-growth
• Ultra-violet light and high altitude increases the severity of the disease

Types

• Fungal or bacterial infection keratitis - Inflammation is due to an infection caused by a fungi or bacterium organism

• Ulcerative keratitis - Inflammation due to an erosion/injury to the surface of the cornea, can progress to the cornea stroma

• Chronic superficial keratitis (also called pannus) - Usually affects German Shepherds, Greyhounds, Labrador Retrievers, and Border Collies

Fungal and Bacterial Infection Keratitis

• Fungi or bacterium
• Bacterial infection may be secondary to ulceration

Ulcerative Keratitis

• Abrasion
• Scratch
• Puncture
• Trauma

Chronic Superficial Keratitis

• Genetic preposition 
• Autoimmune disease (immune system treats the cornea as a threat)

If your dog has been followed previously by another veterinarian it is a good idea to bring his medical records with you when you visit the ophthalmologist. During the consultation the veterinary ophthalmologist will want to know what your concerns are, what symptoms you have observed and when they started.  Please let the doctor know if your pet was injured or experienced trauma of the eye. 

The veterinary ophthalmologist will evaluate the patient’s overall health condition. He will perform an eye examination which may include checking the interior of the eye, and evaluation through a pupillary light reflex test and dazzle reflex test. These tests will check the eye’s involuntary response to intense lighting (blinking, third eye protrusion). Further investigation may include the Schirmer tear test and a measurement of the intraocular pressure.  

If the specialist suspects ulceration he will perform a fluorescein eye test. A few drops of dye are placed in the dog’s eye; the test can locate an area of cell injury. The doctor may also want to have cultures taken to look for bacteria or fungal growth.

Fungal infections are usually treated with antifungal medication such as voriconazole eye drops. Bacterial infections are usually treated with topical and oral antibiotics.

The treatment of ulcerative keratitis will depend on the severity of the ulceration. The patient will be prescribed topical antibiotic and pain medication.  Superficial ulcers usually heal within 5-7 days.  Deeper ulcerations may require several treatments and may take much longer to heal. A soft contact lens may be placed on the dog’s pupil to help protect the cornea while it is healing. Sometimes, surgery may be required to perform conjunctival grafts or a corneal transplant.

Chronic superficial keratitis may be treated with intermittent injections of corticosteroids under the conjunctiva and/or eye drops. Many patients (85%) with chronic superficial keratitis respond to immunotherapy, which suppresses the immune system’s response.

Dogs receiving treatment for a fungal or bacterial infection have a good recovery prognosis.  Follow up visits will be necessary and may include a retake on the culture to ensure the fungi or bacterium is all gone.  The prognosis for dogs with ulcerations depends on the severity of the ulcer.  The patient will need to have additional eye exams to make sure the cornea is healing properly.

There is no cure for chronic superficial keratitis but it can be managed with medication.  This condition will require lifelong treatment.  The patient will need to be seen on a regular basis to monitor his illness and to determine if there are any side effects to the medication.