One of the most common conditions affecting dog’s eyes are ulcers. These can vary from minor to severe, and treatment can equally be simple and quick or complex and prolonged. Today we will discuss eye ulcers, their treatment, as well as if less medications may be better than more.
Table of contents
- What is an Eye Ulcer?
- How Do We Diagnose Ulcers?
- How Are Ulcers Treated?
- Medical Management:
- The first drug most vets will reach for when an ulcer is diagnosed will be topical antibiotics
- Another common product is corneal repair gel, made with hyaluronic acid that aids healing
- Pain relief is critical for ulcers, as they are acutely painful
- If there are underlying conditions these must also be addressed too
- Melting ulcers can require another topical product – plasma drops
- Surgical Management:
What is an Eye Ulcer?
An eye ulcer is damage to the cornea of the eye. The cornea is the clear outer structure of the eye. It is made up of multiple layers, going from the outside in: epithelium; stroma; Descemet’s membrane; endothelium. The deeper the ulcer damage, the more layers are involved. We can thus class ulcers as superficial (epithelial damage), shallow stromal (stromal damage), deep stromal (deep stromal damage), or a descemetocele (damage all the way down to Descemet’s membrane). Generally, the deeper the ulcer the more serious the problem. Deeper ulcers run a greater risk of catastrophic eye rupture.
Ulcers form due to a variety of factors, including trauma or rubbing, foreign bodies, inverted or everted eyelids, rubbing of hairs on faces, inwards-facing or abnormally-placed eyelashes, infection and even neurological or hormonal diseases. Certain breeds are more prone to ulcers, such as brachycephalic breeds with bulging eyes more prone to damage, and those predisposed to dry eye.
Ulcers are painful, particularly shallower ulcers where the nerve endings of the cornea are located. Pain results in redness of the eye, puffy eyes, excessive tear production, cloudiness of the eye, rapid blinking or closure of the eyelids, rubbing the face, thick gloopy discharge and general unwellness. Ulcers can also become seriously infected, resulting in a ‘melting ulcer’.
If untreated, eye ulcers can lead to chronic pain, damage to the eye, reduction or loss of sight, or even loss of the eye in extreme cases.
How Do We Diagnose Ulcers?
Ulcers can be diagnosed first based on the visual appearance of the eye – some ulcers may be obviously seen. The history, breed and symptoms of the dog will help too. Definitive diagnosis is performed by staining the eye using fluorescein stain, which stains the damaged cornea bright green. How the ulcer stains may also help determine how deep it is. A vet should also identify the cause of the ulcer by looking closely at the face shape and structure, checking tear production, eye pressure and more. If the eye is infected, swabs can aid in identifying and treating the microbes.
How Are Ulcers Treated?
Here’s where it gets complicated. Treatment for ulcers varies massively depending on the patient, owner, the specific ulcer and the vet involved. Treatment can take as little as a few days for the simplest ulcers, or many weeks for complex, deep or melting ulcers. As the ulcer progresses, treatment can change. Ulcers are a frustrating condition to treat, for owners and vets. Though not all will have a successful resolution, perseverance is key, particularly when it feels like you are going in circles.
The first drug most vets will reach for when an ulcer is diagnosed will be topical antibiotics
Drugs chosen often include fusidic acid, chloramphenicol or gentamycin. Even if ulcers aren’t seriously infected, any bacteria present will slow down healing, so inhibiting them is key. Many of these drugs come in gel or liquid form that will also lubricate the eye. These should be given two or more times a day. In severely infected eyes (or in dogs where access to the eyes is difficult), oral or injectable antibiotics can be given, though these can be less effective as the blood-retina barrier can block drugs from making it to the ulcerated cornea. Ideally, ulcers should be swabbed so we know what bacteria are present and what antibiotics are needed.
Another common product is corneal repair gel, made with hyaluronic acid that aids healing
This is often given alongside antibiotics two or more times a day. However, there is mixed evidence that these products are effective, with some studies showing they accelerate healing and others that it makes no difference. Since there is evidence it does help some dogs, it should be considered as a treatment option.
Pain relief is critical for ulcers, as they are acutely painful
Not addressing this is, of course, a welfare concern, as well as risking further damage if the dog rubs their eye in pain. The mainstay of treatment is usually oral non-steroidal anti-inflammatory drugs (NSAIDs) such as meloxicam or carprofen. These will reduce inflammation in the eye and provide pain relief. However, they may not be suitable for patients with kidney or liver disease. Topical NSAID eyedrops are an option, however one study noted that topical NSAIDs can lead to slower healing and increased risk of infection. Other pain relief drugs include gabapentin, opioid drugs like buprenorphine, paracetamol and others. Topical atropine can also be beneficial. Lubrication of the eye will also improve comfort and reduce the risk of further damage due to the ulcer drying out.
If there are underlying conditions these must also be addressed too
For example, dry eye can be treated with lubrication, replacement tears, or immunomodulatory drugs that increase tear production.
Melting ulcers can require another topical product – plasma drops
These are drops made from the liquid component of the patient’s blood. The vet will take a blood sample, spin it down to separate the liquid, and put the liquid in a dropper bottle. The plasma is full of healing factors and white blood cells which will fight infection and aid healing for these serious ulcers.
It is important to note that recent literature has shown healing may be quicker when the number of topical products are limited. This is because owners struggle to manage multiple products multiple times a day, and the dog is often reluctant to sit multiple times to have drops applied. Furthermore, there is a theory that a preservative used in many topical antibiotic drops can damage corneal epithelial cells, slowing down healing. Topical ointments don’t have these preservatives, so may be safer. Therefore, it is recommended that for simple ulcers, reducing the number of topical products may result in the ulcer healing faster (more complex ulcers may require multiple products regardless).
In some cases, ulcers require more intense treatment. These usually will not be the first line approach, unless the ulcer is severe, but the next option if medical treatment is not working. However, remember that ulcers can take weeks to heal fully, so although surgical procedures are an option, patience may negate the need for them.
One of the simplest procedures is debriding the eye
Sometimes, the edges of shallower ulcers come away from the underlying layers, creating an underrunning effect. This means the ulcer cannot heal properly. By gently rubbing the surface of the ulcer to remove this loose tissue, the edges can be neatened up and a healthy layer of cells left behind from which the cornea can heal. This is often performed with the dog conscious after local anaesthetic drops have been applied to numb the eye. Debriding can be done with cotton buds or diamond burr drills. A similar procedure called a keratotomy uses a needle to create little scratches on the surface of the cornea, creating more surface area for the ulcer to adhere to (similar to roughing up two pieces of wood before glueing them together). These procedures should not be performed on deeper ulcers, and can be risky in cats that have a greater risk of eye rupture.
There are also two temporary surgeries that can be performed, designed to protect the ulcer as it heals
These are a tarsorrhaphy (closure of the eyelids) or a third eyelid flap (suturing the third eyelid across the eye). As well as physically protecting the eye, these procedures ensure the ulcer is bathed in tear fluid that will be full of healing factors, speeding up healing. These can be left in place for a week or two before being removed, hopefully revealing a healed cornea. Sometimes, if the first surgery fails, a second surgery is required. These require general anaesthetics. Some practices will also have dog contact lenses that can be fixed during surgery (or even conscious) to provide a similar effect.
More intense surgeries involve grafts from the eyelid or conjunctiva – these are sutured over the ulcer permanently, providing support to prevent eye rupture, and helping the ulcer heal. These often will leave scars on the cornea, and should be reserved for very deep or non-healing ulcers.
Finally, in eyes with severe ulcers, for dogs with uncontrollable pain, or if the eye ruptures, enucleation is an option. This is removal of the entire eye, resulting in the ulcer being ‘treated’. It will, of course, result in loss of sight, so should be considered a last resort in ulcer treatment.
While the concept of an ulcer is simple, the condition rarely is. Ulcers can be highly varied and complex to treat. Again, this can be frustrating to deal with. Rechecks may need to be as frequent as daily for very complex ulcers, and costs can easily skyrocket. Treatment should only be stopped when a vet checks there is no ulcer present with fluorescein.
It is important that as an owner you follow your vet’s advice, try and stick to their treatment regime, ensure you come back for rechecks on the ulcer, and discuss concerns or difficulties you are having with them. There are many ways to treat ulcers, so if one treatment isn’t suiting you or your dog, there may be other options available.
- Optimising the medical treatment of canine corneal ulcers, Ruth Marrion, Vet Record 22/29 January 2022
- Corneal Ulcers in Dogs – VCA Hospitals
- Topical Cross-Linked HA-Based Hydrogel Accelerates Closure of Corneal Epithelial Defects and Repair of Stromal Ulceration in Companion Animals
- Effects of topical hyaluronic acid on corneal wound healing in dogs: a pilot study
- Drug transport in corneal epithelium and blood-retina barrier: emerging role of transporters in ocular pharmacokinetics