Keratitis in dogs is inflammation of the cornea, the clear outer layer that covers the front of the eye. It can develop from injuries, infections, immune system problems, or chronic dryness, and it ranges from a mild irritation that clears up with eye drops to a serious condition that threatens your dog’s vision. The hallmark sign is a cornea that loses its clarity, often turning cloudy, reddish, or dark with pigment.
Types of Keratitis
Not all keratitis looks or behaves the same. The type your dog has determines how it’s treated and what to expect long term.
Ulcerative keratitis means the cornea has an open sore. This is the most painful form and often the most urgent. Ulcers can be superficial scratches or deep erosions that risk perforating the eye entirely. Dogs with ulcerative keratitis typically squint hard, tear excessively, and avoid bright light.
Chronic superficial keratitis (pannus) is an immune-mediated condition where the body’s own inflammatory cells invade the cornea. It tends to start at the outer edges and slowly creep inward, bringing blood vessels and a pinkish haze with it. Without ongoing treatment, the inflammation and scarring eventually block vision. German Shepherd Dogs are the most commonly affected breed, though it occurs in others as well. UV exposure worsens pannus, so dogs living at higher altitudes or in sunny climates tend to have more aggressive cases.
Pigmentary keratitis involves dark brown or black pigment spreading across the cornea’s surface. It’s especially common in flat-faced breeds. A study of Pugs in the Canary Islands found pigmentary keratitis in 94.5% of eyes examined. Other research from the U.S. has reported rates around 82% in Pugs, with lower but still significant rates in other brachycephalic breeds like Boston Terriers, Shih Tzus, and Pekingese. The pigment itself is the body’s response to chronic irritation, often from eyelids or lashes rubbing against a cornea that’s overly exposed due to the breed’s prominent eye shape.
What Causes It
The triggers behind keratitis fall into a few broad categories. Trauma is the most straightforward: a scratch from another pet, a thorn, or debris kicked up on a walk can damage the corneal surface and set off inflammation. Bacterial and fungal infections sometimes follow these injuries, turning a simple scratch into an infected ulcer.
Dry eye, known clinically as keratoconjunctivitis sicca (KCS), is another major contributor. When the tear glands don’t produce enough moisture, the cornea dries out, becomes irritated, and is far more vulnerable to ulcers and pigment buildup. KCS is common in breeds like Cocker Spaniels, Bulldogs, and West Highland White Terriers.
Immune-mediated causes drive pannus and some other forms of keratitis. In these cases, there’s no infection or injury. Instead, the immune system mistakenly targets the corneal tissue. Genetics play a strong role, particularly in German Shepherds, where specific immune system gene variants have been linked to higher risk. Anatomical factors matter too. Dogs with bulging eyes, shallow eye sockets, or eyelids that don’t close fully are dealing with constant low-grade corneal exposure, which makes chronic keratitis almost inevitable without management.
Recognizing the Symptoms
The most common visible change is new blood vessels growing into the cornea. A healthy cornea is completely clear and has no blood supply of its own, so any reddish streaks crossing the surface are abnormal. You may also notice cloudiness from fluid buildup, white or yellow cellular infiltrates, or dark pigment creeping across the eye.
Pain symptoms vary by type. Ulcerative keratitis is painful: expect watery eyes, frequent blinking or spasmodic winking, and your dog holding the affected eye partially shut. They may paw at their face or rub it along furniture. Non-ulcerative forms like pannus and pigmentary keratitis are less overtly painful but still cause irritation. A thick, mucusy discharge, especially with dry eye, is another common sign.
In advanced cases, you can see the changes with the naked eye. The cornea may look bumpy or irregular, or a significant portion might be covered in dark pigment or scar tissue. If both eyes are affected symmetrically, that’s a strong hint toward an immune-mediated or breed-related cause rather than trauma.
How It’s Diagnosed
Your vet will start with a close examination of the eye, often using a magnifying lens and a bright light to evaluate the cornea’s surface. Two quick, painless tests give the most important information.
The fluorescein stain test involves placing a drop of orange-green dye on the eye. The dye washes off healthy corneal tissue but sticks to any area where the surface is damaged, making ulcers glow bright green under a blue light. This tells the vet whether an ulcer is present, how large it is, and how deep it goes.
The Schirmer tear test measures how much tear fluid the eye produces. A small paper strip is placed just inside the lower eyelid for one minute, and the distance the moisture travels along the strip tells the vet if tear production is adequate or below normal. Low results point toward dry eye as an underlying cause.
If infection is suspected, a swab or scraping of the cornea can be sent to a lab to identify specific bacteria or fungi. This is particularly important for deep or rapidly worsening ulcers, where choosing the right treatment early can make the difference between saving the eye and losing it.
Treatment Options
Treatment depends entirely on the type and severity. Superficial ulcers from minor injuries often heal within a week or two with antibiotic eye drops to prevent infection and pain relief. For deeper or infected corneal ulcers, more aggressive antibiotic therapy is needed. A combination antibiotic approach tends to cover the widest range of bacteria commonly found in canine corneal ulcers, though your vet may adjust the choice based on culture results from the lab.
Immune-mediated keratitis like pannus is managed with immunosuppressive eye drops that calm the inflammatory response attacking the cornea. These medications reduce blood vessel growth, clear infiltrates, and can halt or reverse pigment deposition if caught early enough. The key reality with pannus is that it requires lifelong treatment. Stopping the drops, even after the eye looks clear, typically leads to relapse.
Pigmentary keratitis treatment focuses on addressing whatever is driving the chronic irritation, whether that’s dry eye, eyelid abnormalities, or corneal exposure. Tear-stimulating drops help with dry eye cases. Surgical correction of eyelid problems can reduce ongoing friction. Immunosuppressive drops are often used alongside these measures to slow pigment progression.
When Surgery Is Needed
Deep corneal ulcers that risk perforating the eye, or ulcers that aren’t responding to medications, typically require surgical repair. The goal is to provide structural support to the weakened cornea and prevent the eye from rupturing. Several approaches exist.
A conjunctival graft uses your dog’s own tissue from the pink membrane surrounding the eye, repositioning it to cover and reinforce the damaged area. A corneal-conjunctival transposition moves a combination of corneal and conjunctival tissue into the defect. In some cases, donor corneal tissue, amniotic membrane, or other biological grafts can be used. Vets generally recommend surgery promptly when an ulcer is deep, but in younger, cooperative patients with ulcers showing clear signs of healing, they may opt to continue medical treatment and monitor closely instead.
After surgery, expect several weeks of frequent eye drop administration and follow-up visits. Some scarring at the graft site is normal and usually fades over time, though it may not disappear completely.
What Happens Without Treatment
Untreated keratitis rarely stays the same. Ulcerative keratitis can deepen over days, eventually perforating the cornea and allowing the internal contents of the eye to leak out. This is an emergency that can result in loss of the eye. Even without perforation, chronic ulcers lead to dense scarring that permanently reduces vision.
Pannus and pigmentary keratitis progress more slowly but just as relentlessly. Over months to years, the cornea becomes increasingly opaque from scar tissue, blood vessels, and pigment until functional vision is lost. The earlier treatment begins, the more corneal clarity can be preserved.
Protecting Your Dog’s Eyes
If your dog has been diagnosed with keratitis or is at high risk due to breed, a few practical steps reduce the chance of flare-ups or new injuries. A recovery cone or protective collar prevents pawing and rubbing at irritated eyes, which can turn a minor problem into a serious ulcer. Keep rough play with other pets to a minimum, especially if your dog is a brachycephalic breed whose eyes are more exposed and vulnerable to scratches. Avoid letting your dog run through tall grass or dense brush where plant material can poke the eye.
For dogs with pannus, reducing UV exposure helps. Dog-specific goggles (sometimes called “doggles”) can shield the eyes during outdoor time, and limiting midday sun exposure in bright climates makes a measurable difference in how aggressively the condition progresses. Consistent, long-term use of prescribed eye medications is the single most important thing you can do. Skipping doses or stopping treatment because the eye looks better is the most common reason keratitis returns.