DOGS AND CATS · OWNER EDUCATION
Corneal Ulcers in Dogs and Cats
A corneal ulcer is a wound on the normally clear surface at the front of the eye. Even a small wound is painful; deep or infected ulcers can threaten sight or rupture the eye.
THE SHORT VERSION
What matters for your animal?
Start with the warning signs and when-to-contact sections if your animal is unwell. The same outward change can have several causes, so this guide helps you prepare questions rather than identify a diagnosis on your own.
What is this condition?
A corneal ulcer is a wound on the normally clear surface at the front of the eye. Even a small wound is painful; deep or infected ulcers can threaten sight or rupture the eye.
The cornea is the clear window at the front of the eye, so an injury affects both comfort and the passage of light. Treatment must address why that surface was damaged as well as protect it while it heals. This explains the combination of eye medication, a protective collar, and repeat examinations: each serves a different purpose, and apparent comfort cannot replace confirmation of healing.
Which species does this guide cover?
The species listed above are the focus of this guide, rather than a complete list of every animal that can develop this condition. Causes, testing and treatment may differ between species and individual patients.
Both dogs and cats can develop corneal ulcers. The cause, depth and healing pattern determine the plan; a painful eye needs prompt examination in either species. Eye medication must be prescribed for the individual patient.
Why can it happen?
- Scratches, foreign material, dry eye, abnormal eyelashes and eyelids can damage the surface. Short-faced dogs may be more exposed to injury.
Inflammation is the body's response to irritation or injury. It can produce swelling, discomfort, and changes in how an organ works, but the word does not identify the cause. Infection, immune activity, trauma, and other processes can all cause inflammation. This distinction matters because an antibiotic treats susceptible bacteria, while inflammation caused by a different process needs a different plan. A temporary improvement in redness or discomfort does not, by itself, establish which cause was present.
What might an owner notice?
- Squinting, watering, rubbing the face, redness or a cloudy spot. A dog or cat may hold the eye shut rather than visibly cry.
An eye can be painful even when there is little discharge. Holding it partly closed, avoiding light, rubbing the face, or becoming reluctant to move through familiar surroundings can be important clues. Surface injury, inflammation inside the eye, and abnormal pressure can look similar from outside. Looking at a photograph cannot replace examination of the structures and measurements that distinguish them. A sudden change in sight or a painful eye deserves prompt attention because some eye problems progress quickly.
How is the problem investigated?
Fluorescein dye highlights a surface defect. Tear production, eyelids and ulcer depth are assessed; infected or slow-healing wounds may need culture or specialist examination.
Fluorescein is a dye used to reveal defects in the corneal surface. The pattern of staining helps the veterinarian assess the wound, but it is only one part of the eye examination. Tear production, eyelid position, foreign material, infection, and the depth of injury can influence treatment. Repeating the examination during healing helps determine whether the surface has actually closed. Less squinting is encouraging, but comfort alone does not prove that an ulcer has healed.
What might treatment involve?
Prescription eye medication, pain relief and an Elizabethan collar protect healing. Deep, infected or nonhealing ulcers may need a procedure or surgery.
Antibiotic selection depends on the suspected or confirmed bacteria, the site of infection, and the animal's safety needs. A culture identifies organisms that grow from a sample; susceptibility testing helps assess which medicines may work against them. The laboratory result is considered alongside tissue penetration, dosing feasibility, and the clinical response. Antibiotics do not treat viruses, and adding one without a clear reason can obscure the investigation or cause adverse effects. Follow the current prescription rather than using leftovers from a previous illness.
Damaged skin or other protective surfaces can become painful and vulnerable to contamination. Treatment considers the depth of injury, affected tissue, infection, and any reason healing may be impaired. Surface cleaning alone may not address deeper damage. The veterinarian may need to remove unhealthy material, provide pain control, protect the site, or investigate an underlying disease. Report new odor, discharge, swelling, darkening, or reduced use of the affected area, and follow the prescribed dressing or protection instructions exactly.
This is an overview, not a prescription or a recommendation for a specific individual animal.
What can owners do at home?
Give eye medication at the prescribed intervals and keep the protective collar on. Attend rechecks even if squinting improves.
Comfort is assessed through behavior and function as well as obvious crying or vocalization. Changes in posture, movement, grooming, sleep, social interaction, or willingness to be handled can be useful clues. Compare the animal with its own normal behavior rather than with another animal. Keep a short record of what it can do comfortably and share changes with the care team. If pain control appears inadequate, contact the veterinarian; increasing a dose or combining medicines without advice can introduce serious risks.
Avoid actions that could make care less safe.
- Do not use leftover eye drops: steroid-containing drops can worsen an ulcer. Prevent rubbing; never try to remove embedded material yourself.
What can the longer-term outlook involve?
Superficial ulcers often heal with appropriate care. Deep wounds have a more uncertain outlook and may leave scarring or loss of vision.
A recheck is not simply a repeat of the first appointment. It assesses whether the original problem is improving, whether complications are appearing, and whether the treatment remains appropriate. The useful measures may include comfort, function, intake, body weight, examination findings, or selected tests. Ask which changes are expected before the visit and which should trigger an earlier call. Improvement in one sign does not always mean that every part of the disease has resolved.
Can risk be reduced?
Address dry eye or eyelid problems and protect eyes during grooming. Recurrent ulcers need investigation.
When should you arrange care?
- Arrange same-day care for a painful or closed eye; sudden cloudiness, trauma or apparent vision loss needs urgent assessment.
Seek urgent veterinary advice if you notice:
DO NOT DELAY URGENT CARE- Seek urgent care for sudden vision loss, eye trauma, severe cloudiness or a very painful eye.
What information helps the care team?
Write down when changes started, what makes them better or worse, actual food and water intake, and all medicines and supplements. Short videos and a medication-label photo can help describe changes that may not appear during the appointment.
How should you understand the tests?
Ask what each proposed test is intended to answer. Some tests identify a cause; others assess severity, organ function or treatment safety. Results are interpreted with the examination and history. A normal result does not exclude every problem, and an abnormal result does not always explain every sign.
Questions to ask before leaving
- What is confirmed, and which other explanations are still being considered?
- What changes should we expect with the proposed plan, and when should we reassess if they do not occur?
- Which observations should I record, and which changes mean I should call sooner?
- What medicine or home-care problems should I report, and what are the instructions for a missed dose or suspected side effect?
- When is the recheck, what will it assess, and whom should I contact after hours?
A care plan may be adjusted as results or the response become clearer. Keep the written instructions and tell the team if cost, handling or administration difficulty makes the plan hard to follow.
Sources behind this guide
Corneal Ulcers in Dogs | VCA Animal HospitalsVeterinary, university or animal-health guidance ↗VCA: Corneal Ulcers in CatsVeterinary, university or animal-health guidance ↗Content last reviewed: October 4, 2026. Review status: veterinary-informed; independent veterinarian review not yet completed.