Dog and Cat Corneal Ulcers

Corneal ulcers in dogs and cats are known to be very painful. We veterinarians can tell by the way pets squint when they have them. Some dogs’ eyelids can be nearly impossible to open because of the pain.

In addition, we know from people that corneal ulcers are reported to be the second-most-painful physical abnormality people can experience.  Kidney stones in ureters are known to be more painful.

A corneal ulcer is any defect causing a disruption of the outermost layer of the cornea. The cornea is the clear part of the eye we see through. Its structure is layered, like an onion.

Corneal ulcers may sometimes be seen with the naked eye or a small amount of magnification. If we are in doubt about the presence of an ulcer, we apply a fluorescein stain to the cornea for confirmation. If the outermost layer of the cornea is intact all of the fluorescein stain will rinse away. If there is a defect in the outer protective layer, stain will remain in the damaged area. If the ulcer is large we can easily see the outline of it. Small ulcers may be illuminated with ultraviolet or “black” light.

Ulcers most commonly occur as a result of infection which erodes that outer protective layer and possibly deeper layers, as well.

Defects in the cornea may also occur with trauma, such as a cat or stick scratching the eye. Trauma may also occur when hair on the eyelids rubs on the cornea or low tear production causes the cornea to dry out.

Treatment of damage to the cornea is driven by the cause of the damage. Secondary problems, such as glaucoma may be present and may affect treatment. For example, if a foreign object has entered the cornea any remaining particles must be removed and the eye protected from infection. If the defect is deep enough it may require surgical repair including suturing and/or conjunctival flap.

As mentioned, infection is the most common cause of corneal ulcer, and most simple, superficial ulcers will heal with appropriate antibiotic and/or antifungal medication.

Often we use autologous serum as treatment for corneal ulcers. To obtain autologous serum we take a blood sample from the patient or another dog or cat known to be healthy. That blood sample is centrifuged or spun to separate the blood cells from the liquid components of the blood. The resulting serum is then applied via medicine dropper two or more times each day until the lesion is healed. Heterologous serum is obtained from a different patient from the one in which it’s being used. One works as well as the other.

NSAIDs or Non-Steroidal Antiinflammatory Drugs may be used orally to effect a reduction in irritation in an inflamed eye. As my ophthalmology mentor, Dr. Laurence Galle says, “Eyes love Rimadyl.”

See you tomorrow, Dr. Randolph.



    • Autologous serum isn’t going to control an infection, but it can certainly provide healing factors that can aid in the fight. Thanks for reading, Dr. Randolph.

      • Can serum, (donated) from other patients, be used on one patient or should it be pulled only from that particular patient?

        • Thank you for a great question, one I should have addressed in the article. I just updated it. “Heterologous serum is obtained from a different patient from the one in which it will be used. One works as well as the other.” Thanks for reading, Dr. Randolph.

    • Cross-species treatment such as this has been used, but it’s generally recommended that the same species serum be used, although it is not necessary for the serum to come from the patient being treated. Thanks for reading, Dr. Randolph.

  1. I have a 10 year old shitsu mix that went through treamtment fora very large corneal ulcer with our normal vet that tried all kinds of antibiotics, ointments, and serums. He has been given Rimadyl and I am almost out of them. We finally took him to an eye specialist but can not afford the $5,000 on the surgery.

    Some days I can tell he is in so much pain. Should I go back to my vet to get Rimadyl as a treatment for the pain or should I conside giving him over the counter asprin type pain releivers sold at pet stores or worse yet consider having the eye removed.

    • It is not wrong to consider enucleation as the only affordable way to relieve pain. Dogs and cats acclimate extremely well to blindness, especially, though, when they still have one eye from which to see. You need not feel guilty about having the eye removed. Thanks for reading, Dr. Randolph.

  2. Our 14-year old cat with a corneal ulcer is getting Tobramycin and Remend drops. Our vet also got a “dog-mom” to donate some blood to create a serum for use. The serum is so thick that it is mostly wasted in trying to get “a drop” out of the syringe. It was told to us that using another species is more beneficial. Can a human’s blood be use? Is there a way to thin it or use a different type of applicator to not waste so much of the precious serum?

    • Thick? This is very strange to me. I’ve used gallons of autologous serum and heterologous serum, and I’ve never seen it be thick before. Perhaps the problem is the opening of the container. We use a 1 oz. Boston round bottle and it dispenses just fine. Did you ask your pet’s doctor about it? Maybe he could offer you a different container. Let me know, please. Thanks for reading, Dr. Randolph.

  3. My kitty was diagnosed with a corneal ulcer and was given a antibiotic drop, not much improved, so the following week a ointment zithromycin was given, this does seem to be helping much better as he is holding his eye at least half open now where before he wouldn’t open it at all, however they used a stain to locate the ulcer and I can now see it with my bare eye, does this indicate its healing or should I be alarmed, he has a vet appointment monday, however I will schedule a sooner appt if this is not indicative of the normal healing process. Thanks so much for your time! Please help, I feel horrible for my fur baby!

    • While it’s impossible for me to say whether the kitty’s eye is healing properly, having not seen it, I am a little concerned that you can see a defect, so, it wouldn’t hurt to make an appointment for a quick, interim checkup and possibly staining, just to be sure we’re not looking at a worsening. It’s not unusual for cats to have ulcers that are Herpesvirus-related. These viral complications may need additional components of therapy. Some may even require referral to a board-certified veterinary ophthalmologist. Thanks for reading, Dr. Randolph.

  4. I am wondering, the blood sample was taken from MY canine and is used as the serum. She has one “blind” eye. The eye with the ulcer had been operated on and has a lens. Now she is too old to do the other eye. BUT, would that serum possibly “help” the blind eye. I am thing “stem cells”. Is the Serum anything like stem cells? I am very frustrated by the return of the cataract to the operated on eye and the lack of anything that can be done for the eye that was just sketchy when the first operation was done and we hoped it would not develop further. Now they do not want to use anesthesia. She is very spunky, active and healthy otherwise.

  5. My cat was recently prescribed plasma drops along with Ofloxacin drops. The latter doesn’t seem to bother him but the plasma drops evidently do as he jerks almost immediately after applying it. Is this normal and how long should this therapy be used? We’re on week two and at times I feel he’s improving but it appears short lived. 1 or 1.5 days b4 I see him squinting again.

    • I’m guessing it’s the cold that is causing the plasma to induce a response. Because it has no preservatives and must be kept cold, that can be uncomfortable. You can put a small aliquot in a syringe and let it come to room temperature before administration. Duration of therapy is definitely a question only his attending doctor can answer, as it depends on the original diagnosis and response to therapy.

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