Recently, an i Love Dogs, Inc. employee woke up to a very disturbing sight. Her 4-month-old Pit mix was suffering from an infected eye that had completely deflated. Any pet parent can imagine the panic that such an alarming situation would create. An immediate trip to the veterinarian revealed that the little guy was dealing with a corneal ulceration that had escalated to a dangerous level where he was at risk of losing his eyesight.
Corneal ulcers are among the most common eye problems that most dogs will suffer from. Many pet parents will come across this eye affliction on possibly more than one occasion, so it’s important to understand the causes and symptoms of corneal ulcers and, more importantly, the treatments involved in taking care of this ailment.
The cornea in the eye is the “clear outer capsule of your pet’s eye,” writes Ron Hines, DVM, on 2ndchance.info. The cells in the cornea are the only ones in the entire body that are transparent and that are nourished by tears as opposed to the blood vesicles that support cells in the rest of the body.
The eyes of a dog, as in humans, are extremely delicate, and the cornea is even more so as it sits on the outermost layer of the eye, delicate yet protruding and therefore susceptible to damage from scratches and scrapes. These scratches and scrapes can turn into ulcerations.
“Corneal ulceration is loss of the corneal epithelium (the outermost cells of the cornea) with exposure and possible loss of the underlying corneal collagen,” writes PetPlace.com. “Corneal epithelium is constantly being lost and replaced, and its health and thickness depend on a delicate balance between cell loss and regeneration.”
As Dr. Hines explains, ulcers in the cornea are categorized according to the depth of the abrasion. The levels range from a superficial corneal ulcer where solely the outer layer of the cornea is lost, to deep corneal ulcers where “more than one half the thickness of the cornea is lost.” The lower level ulcers can heal quickly, while deeper ulcers may take weeks.
What Causes Corneal Ulcers?
Many pet parents may think that the causes of corneal ulcers are solely due to foreign objects scratching the cornea, but the causes are various and could have nothing to do with scrapes from foreign objects.
The most common cause of a corneal ulceration is dry eyes, says Dr. Hines. A lack of protective tears to keep the cornea moistened can lead to an ulcer. Known as “dry eye” or keratoconjunctivitis sicca, this decrease in the production of tears, agrees PetPlace.com, creates “inadequate blink responses” that leads to ulcers.
Other potential causes mentioned by PetPlace.com and Dr. Hines include:
Injury from ingrown or misplaced eyelashes (dystrichiasis)
Eyelids that curl inwardly (entropion) or outwardly (ectropion)
Exposure to foreign material, chemicals, heat or smoke
Infections with certain viruses, bacteria or fungal infections
Trauma such as cat scratches, thorns, bee stings, etc.
While all dogs can fall victim to ulceration, older dogs are at higher risk to suffer a serious infection because of their inability to heal as quickly. Similarly, dogs with protruding eyes and larger eyelid openings are at greater risk for ulcers, says PetPlace.com.
What are the Symptoms?
To determine whether or not a dog is suffering from a corneal ulceration, pet parents should look at the dog’s symptoms to get a better idea. Hines and PetPlace.com give the following list of potential symptoms to look for:
Squinting and Increased Tearing: An affected cornea will be irritating and painful for a dog. Your pet’s natural reaction will be to squint and the eye will tear. This reflex, explains Hines, is called blepharospasm.
Mucus or Pus Draining From the Eye: Corneal ulcers are not only painful but will itch painfully as well. A dog will try its best to rub its eye thereby making the ulceration worse. In response, the eye will discharge a mucus or pus-like fluid that can collect in the corner of the eye nearest the dog’s nose. The blood vesicles of the white of the eye (sclera) will then enlarge with blood, states Hines.
Cloudiness of the Cornea: Dogs with corneal ulcers will often have cloudy eyes. This is because, as Hines describes, larger corneal lesions will cause the cornea to swell with fluid and will turn the cornea a white color.
Other symptoms of a corneal ulcer include inflamed, red conjunctiva (the normally pink tissue surrounding the cornea and lining the eyelids), inability to see the eye because the third eyelid is covering it, and occasional lethargy.
Though smaller abrasions may heal quickly, if there’s an infection involved it can facilitate a progression of the ulcer toward deeper layers of the cornea.
“Once much of the cornea has been eroded away, a bulge may form similar to a sidewall blowout on a tire,” writes Hines. “Such a bulge is called a descemetocele. If a descemetocele bursts, the anterior portion of the eye will collapse and the contents will spill out, destroying the eye.”
To avoid a descemetocele, pet parents should watch for all of the above symptoms and immediately seek the advice of a veterinarian who can make a diagnosis and proceed with treatment before the ulcer reaches this point.
How are Corneal Ulcers Diagnosed?
If you have a feeling that your dog may have sustained a corneal ulceration, it’s important to get him or her to a veterinarian right away. Once there, your dog’s veterinarian can run the proper diagnostic tests to help determine first if your dog has a corneal ulcer and secondly how severe the abrasion may be at that point.
As Hines describes, your veterinarian will run a thorough ocular examination “paying special attention to the eyelashes, eyelids and blink reflex, status of the cornea and the interior of the eye.” This will help your veterinarian determine which tests to run.
Your vet will most likely run one of the following eye exams:
Fluorescein Dye Test: Using fluorescein dye strips, your veterinarian will anesthetize the eye. With strips moistened with saline and the fluorescein dye the vet will allow the dye to flow out over the cornea. Your dog’s vet will then delicately wash out the dye with saline. If your dog’s eye is normal, no dye will remain on the cornea. As Hines explains, “Fluorescein dye attaches only to raw abraded areas where it can be seen when viewed with an ultraviolet light source through an ophthalmoscope.”
Shirmer Tear Test: The Shirmer tear test measures the eye’s tear production. As previously discussed, corneal ulcers can be caused by lack of tear flow to the eye. This test helps your veterinarian determine if the cause of the ulcer is in fact “dry eyes.”
Intraocular Pressure: Hines says that if he suspects that the pressure in the dog’s eye is too high (glaucoma) and that the distortion of the shape of the eye is the underlying cause of the ulceration, he’ll usually perform another test. Using a Schiotz tonometer, he’ll measure the pressure in the dog’s eye. Ulcers due to increased intraocular pressure require a different course of treatment.
PetPlace.com adds that some veterinarians may run cytology, culture and antibiotic sensitivity tests of ocular samples to see if “infectious agents such as bacteria” are present that could be the possible cause of the ulcer.
How are Corneal Ulcers Treated?
After reading this far, it might be obvious that a simple scratch to the cornea can result in something much more serious than an itchy eye. A superficial ulcer, if left untreated can progress to something more complicated and can ultimately destroy a dog’s vision.
As Hines explains, most veterinarians will prescribe a treatment based on the severity of a dog’s corneal ulcer, how long they’ve had it and based on what may be the underlying cause of the ulcer. “I focus on treating and preventing secondary infection, controlling inflammation and pain, preventing additional corneal damage, and minimizing damage to the cornea by limiting scar formation,” says Hines.
Treatment options for corneal ulcerations according to Hines and PetPlace.com include:
Removal or Treatment of the Underlying Cause: For example, Hines explains that if a dog develops an ulcer because of insufficient tears or a bulging eye he’ll place the dog on eye drops or artificial tears.
Antibiotic Eye Drops or Ointment: Your veterinarian will most likely prescribe an antibiotic eye drop or ointment to treat or prevent infection of the cornea. “Corticosteroid-containing medicines should never be used with corneal ulcers because they retard the healing process,” says Hines. “Ointments and drops need to be applied very frequently to affected eyes. I generally suggest every two to four hours in newly treated eyes.”
Oral Antibiotics: When a dog has a more serious infection in its cornea, a veterinarian may prescribe an oral anti-inflammatory drug such as aspirin if there’s inflammation in the eye.
Elizabethan Collar: Every dog’s best friend, an Elizabethan collar can help prevent a dog from further damaging his or her eye. Hines also suggests bandaging the paws to prevent the dog from pawing at the eye and injuring itself further.
Atropine: Atropine is used by veterinarians to dilate the dog’s pupil and to relieve the pain a dog endures when the inner layer of the eye is inflamed or the iris spasms. Dogs with corneal ulcers are very sensitive to bright light. Atropine’s ability to dilate the pupils helps relieve some of that pain.
Surgery: In serious cases, treatment can involve surgery. A veterinarian might apply a soft contact lens to the eye or suture the eyelids partially closed to bandage the eye. A vet may also place conjunctival grafts over deeper lesions.
Treating Indolent Ulcers: As Hines explains, “Indolent ulcers are ulcers that refuse to heal. These can occur when a ledge of dead corneal tissue surrounds the ulcer. These ulcers can be encouraged to heal if this dead tissue is scraped away.” When scraping takes place, new tissue has the opportunity to spread over the ulcer.
Treatment At Home: Though most pet parents may feel frustrated or at a loss for how to help their dogs heal, there’s a good amount they can do to ensure their dog stays on a healthy course. At home, follow all of your veterinarian’s guidelines for administering medications to your dog. Make sure to take your dog in for follow-up visits so that the veterinarian can check the eye.
Pet parents can also make sure to keep their dogs from rubbing their eyes by keeping the Elizabethan collar on their dogs at all times. They can also be strongly observant, making sure the eye isn’t worsening. If cloudiness, ocular discharge, squinting and redness continues, pet parents should seek veterinary advice immediately.
How are Corneal Ulcers Prevented?
Preventing corneal ulcers is as simple as staring into your dog’s eyes every day, which we’re sure is a daily ritual for most pet parents who love their dogs. While you’re staring into your dog’s eyes with undying love, take a quick peek around to determine if anything looks out of the ordinary. If you notice that your dog has pain or if you see a change in color in the eyes, it’s best to contact your veterinarian.
If you have the kind of dog that spends a lot of time in the brush or out in the fields, you should always examine the dog’s eyes when play/work time is over. Dogs who spend a lot of time in these areas are more likely to suffer trauma to the eyes and could eventually develop a corneal ulcer.
Take care not to expose your dog to chemicals that would cause corneal ulcers. Avoid accidentally getting shampoo, soap or household cleaners in their eyes. Keep your dog’s eyes away from irritating heat or smoke. If your kitty likes to take swings at your dog with claws flying, do your best to keep an eye on them when together, and separate them when you’re not able to supervise.
As previously touched upon, keep your dog’s breed in mind. If you have a dog with protruding eyes (such as a Pug or Boston Terrier) take care to be extra careful with him or her. The corneas of Boston Terriers and Boxers don’t heal as well as those of other breeds. So if you’re a pet parent to one of the two, it’s important to take precautions and to stock up on vitamin E, says Hines, because this crucial vitamin will help with the healing process.
Protecting your dog’s eyes from potential disaster is your first line of defense against corneal ulcers and will help you prevent your dog from suffering vision loss.
Find A Vet HOW TO articles are intended for informational purposes only. You should always consult with your veterinarian about any health issues affecting your dog.
Have your dog ever experience a corneal ulceration? Tell us about your experience in the Comments section below.