Corneal ulcer in dogs is an injury to the transparent structure of the eye caused by external trauma.
Corneal ulcers are painful and can be aggravated by infection or trauma (eg scratching), and monitoring by a veterinarian is recommended.
Treatment consists of the use of antibiotics, anti-inflammatories, and mydriatics. Superficial corneal ulcer, with treatment, heals in 2 to 6 days .
What is a corneal ulcer?
The cornea is the transparent structure in the eye that allows light to pass through and protects the eye. Its exterior is composed of corneal epithelium covered by a tear film.
When there is an injury with loss of epithelium and inflammation we have a corneal ulcer (canine ocular ulcer or ulcerative keratitis).
Sores, scratches, or punctures (holes) in the clear part of the eye are examples of corneal ulcers.
Corneal ulcers in dogs and cats are classified according to the depth of the lesion. Thus, there are several types of canine corneal ulcer:
- Uncomplicated superficial ulcer: when the lesion is superficial, not very serious;
- Deep ulcers: when the injury is deep, with greater risk;
- Indolent ulcers: superficial ulcers in which healing does not occur;
- Total ulcers and descemethocelium: when the ulcer is so deep that there is only one layer of the cornea in the lesion or there is perforation (emergency ).
Superficial ulcers can become deep if the animal scratches or due to secondary infection. In deep ulcers, you may see a bulge in the cornea that corresponds to the inner layer.
Corneal ulcer signs in dogs
The cornea is a very sensitive tissue. Therefore, corneal ulcers are extremely painful . The dog will express this pain by scratching the eye with the paw or on surfaces, blinking (blepharospasm), and tearing.
Other pain-related signs include protrusion of the nictitating membrane and sensitivity to light (photophobia).
The ulcer may be visible as a depression, swelling, or irregularity in the cornea . The eyes may become swollen due to the accumulation of fluid called corneal edema.
The eyes may become reddened due to the appearance of blood vessels resulting from inflammation and scarring (conjunctival hyperemia).
The appearance of pus or white material in a ring around the ulcer may suggest a secondary infection. On the other hand, corneal ulcer healing in dogs may be seen as a white opacity.
What are the causes of corneal ulcer?
In dogs, most ulcers are caused by trauma . This includes fingernail scratches, foreign objects entering the eye (eg sand, twigs) or exposure to chemicals.
Another cause is lack of tears, or dry eye (eg keratoconjunctivitis sicca), or endocrine diseases (eg diabetes, hypothyroidism, hyperthyroidism).
Brachycephalic (short-muzzled) dogs are more predisposed to canine ocular ulcers. Their eyes are more prominent and exposed to environmental aggressions.
Abnormal eyelid morphology can also lead to injuries to the eye that result in a corneal ulcer.
An abnormal morphology is lagophthalmos , when the dog cannot close the eyelids completely. The eye is dry and exposed and predisposed to injury.
Infections can be the cause of ulceration, but they usually appear after the injury . The presence of a white, pus-like discharge from the ulcer suggests that it is infected.
Diagnosis of corneal ulcer in dogs
The corneal ulcer is very painful and its evolution can lead to blindness. Therefore, you should make an appointment with your veterinarian if you suspect a corneal ulcer.
The diagnosis will be made during a veterinary ophthalmological examination. A dye, fluorescein , is used to determine the presence of an ulcer.
The dye is applied in a drop or strip and will stain the ulcer area of the cornea green , binding to the internal tissue exposed in the lesion.
The veterinarian will assess the depth of the ulcer and factors that may delay recovery. These factors include perforation or dissolution of structures or the presence of infection.
Corneal ulcer treatment in dogs
Treatment consists of facilitating corneal healing , often by applying eye drops to the corneal ulcer in dogs.
Without proper treatment, canine eye ulcers can lead to vision loss. Corneal ulcer should be treated as soon as possible to increase the success rate.
Deep ulcers in dogs can be complicated, forming full-blown ulcers when the eye is punctured. Without treatment, there is a risk of losing the eyeball.
Treatment of superficial corneal ulcers
Most corneal ulcers in dogs are superficial. Treatment involves removing the cause of the trauma (eg removing the foreign object from the eye) and applying topical antibiotics to the eye (eye drops).
Atropine or tropicamide may be used to relax the pupil (mydriatic) and reduce pain. As they reduce tear production, they should be combined with the application of artificial tears.
Oral anti-inflammatories (eg diclofenac) may be used to control ulcer inflammation and allow healing. Topical corticosteroid-based anti-inflammatories are not recommended because they inhibit eye defenses and healing.
The use of the Elizabethan collar (cone) is recommended to avoid additional trauma that can occur when the dog scratches the eye.
Simple corneal ulcers should heal within 2 to 6 days . If there is no apparent resolution after 7 days, it may be a more complicated case.
Treatment of other corneal ulcers
The remaining cases of ulcers have more complicated treatments.
The treatment of deep corneal ulcers is similar to the treatment of superficial ones. In cases where the depth of the ulcer exceeds 50% of the corneal thickness, surgery should be performed.
Surgery consists of sutures, transplants, or covering the ulcer with a flap of nearby tissue, such as that of the third eyelid (nictitating membrane). This surgery protects the ulcer and prevents it from getting deeper. Healing should occur within a month.
In total ulcers , where there is total perforation of the cornea, they must be treated as emergencies. Surgery is similar to that described earlier for deep ulcers.
Complicated ulcers are those where there are risk factors that delay healing or destroy the cornea (eg infection, uveitis , keratodermatitis sicca, abnormal eyelid morphology).
Complicated ulcers are treated with topical antibiotics, saline, atropine, and anti-inflammatories. The treatment is carried out at short intervals (every hour) and requires clinical reassessment, with the animal being hospitalized .
Indolent ulcers are recurrent or slow-healing superficial ulcers. That is, they are corneal ulcers that do not heal.
Indolent ulcers occur because the growing epithelium does not adhere to the basement membrane. It is more frequent in elderly animals and is common in the Boxer breed.
Treatment involves removing the affected cell layer (debridement) to allow better healing tissue adhesion.
This removal can be performed with a swab, with a needle, or with surgery followed by topical medication. Surgery is recommended in the most difficult cases.
Healing of indolent ulcer after treatment may take up to 3 weeks. The tissue will only be fully healed after a year. Despite the cure, there is a risk of recurrence.
Questions and Answers about Corneal Ulcers in Dogs
Is the corneal ulcer curable? Yes, dog eye ulcers are curable. Veterinary follow-up is essential to ensure healing. Without treatment, it can get worse leading to opacification and blindness.
What does healed corneal ulcer look like in dogs? During treatment, there may be corneal opacification followed by resolution. This opacification is due to scar tissue.
Is the scar on the dog’s cornea curable? The temporary opacification formed in healing should resolve in cases of a simple superficial ulcer. More complicated cases with severe tissue injuries may be opaque.
How long does corneal ulcer treatment last in dogs? The treatment of the superficial ulcer lasts a week, until its resolution.
How long does it take for a dog’s eye ulcer to heal? Superficial ulcers should heal within a week. Deep ulcers heal within a month of surgery. Indolent ulcers heal within a year after surgery.