Terramycin eye ointment for dogs and cats: uses and safety

Terramycin is an antibiotic eye ointment for animals. It combines two antibiotics, oxytetracycline and polymyxin B, and vets use it for bacterial infections of the surface of the eye in dogs and cats, such as conjunctivitis. It does not treat viruses, dry eye, glaucoma or allergies, and it should only go into an eye that a vet has examined.

That last point matters most for older pets. A red, cloudy or weepy eye in a senior dog or cat is often something other than a simple infection, and some of those causes can cost the eye within days.

What is Terramycin used for?

Terramycin ophthalmic ointment is labeled for surface eye infections caused by bacteria that are sensitive to its two ingredients. Vets commonly use it for:

• Bacterial conjunctivitis (pink eye): red, swollen inner eyelids with discharge
• Infection of the eyelid margins (blepharitis)
• Infection of the cornea (keratitis), and infected or at-risk corneal ulcers, as part of a plan the vet sets
• Bacterial infection on top of another illness, for example a cat with an upper respiratory virus whose eyes have become secondarily infected

The two antibiotics cover different groups of bacteria, which is why they are paired. The ointment contains no steroid and no pain reliever.

Terramycin for cats

Oxytetracycline belongs to the tetracycline family, which is active against chlamydia and mycoplasma, two organisms that commonly cause conjunctivitis in cats. That is one reason it is often chosen for cats.

Many feline eye infections start with a virus, most often feline herpesvirus, and no antibiotic acts on a virus. A cat with weepy eyes and sneezing may need different or additional treatment, which is the vet's call.

Terramycin for dogs

In dogs, a straightforward bacterial eye infection is less common than people expect. Discharge and redness are more often a sign of something underneath: dry eye, an eyelid problem, an allergy, a scratch or a foreign body. An antibiotic ointment can tidy up the discharge for a while and leave the cause untouched.

Why an older pet's eye should be examined first

Several serious eye conditions look like an infection from across the room, and they become more common with age:

• Dry eye. The eye stops making enough tears. It is common in older dogs and causes thick, sticky, yellow-green discharge that returns as soon as an antibiotic is stopped. It is usually managed with medicine that helps the eye make tears, not with an antibiotic alone.
• Glaucoma. Pressure builds inside the eye. The eye is red, cloudy and painful, and sight can be lost quickly. See our pages on glaucoma in senior dogs and glaucoma in senior cats.
• A corneal ulcer. A scratch or erosion on the clear front of the eye. It is painful, causes squinting and tearing, and can deepen fast. The vet finds it with a dye test.
• Inflammation or bleeding inside the eye, which can be linked to illness elsewhere in the body, such as high blood pressure in an older cat.
• Eyelid growths that rub on the eye.

A vet can usually separate these in one visit with a tear test, a dye test and a pressure reading. Nobody can do it by looking. If the eye looks cloudy, our page on cloudy eyes in older cats explains what the different kinds of cloudiness can mean, and a raised third eyelid is its own warning sign.

Is Terramycin eye ointment sold over the counter?

In the United States, not any more. Terramycin was sold over the counter for many years, but its label now carries the federal prescription caution, which restricts it to use by or on the order of a licensed veterinarian. The change came in 2023, when the FDA asked the makers of the remaining over-the-counter animal antibiotics to bring them under veterinary oversight. In many other countries antibiotic eye ointments for pets are also prescription only. Rules differ by country and can change, so ask your vet or pharmacist if you are unsure.

If you find it offered without a prescription, that does not make it the right treatment. The ointment will not help a viral infection, dry eye, glaucoma or an eyelid problem, and the delay while you try it can do harm. Treat it as a medicine your vet chooses after examining the eye.

Do not substitute a human eye ointment or drops, an old tube from a previous problem, or another pet's medicine. Some eye products contain a steroid, which can make a corneal ulcer much worse. Antibiotic skin ointments are not made for eyes at all.

Is Terramycin safe for cats?

Most cats tolerate it without trouble, and it is widely used. There is one rare but serious risk owners should know about, and the product label carries a warning about it. Severe, life-threatening allergic reactions (anaphylaxis) have been reported in some cats after antibiotic eye preparations were applied. In the largest published review of these cases, every product involved contained polymyxin B, one of the two ingredients in Terramycin. Cause and effect was not proved, and the reaction appears to be rare.

The reported reactions came on within four hours of an application, many of them within minutes. Stay with your cat after applying it, keep an eye on them for the next few hours, and treat any of these as an emergency:

• Sudden vomiting, drooling or diarrhea
• Swelling of the face, lips or eyelids, or sudden itching
• Labored, noisy or open-mouth breathing
• Pale gums, sudden weakness, wobbling or collapse

Tell your vet if your cat has ever reacted to an eye medicine or an antibiotic. The published reports are in cats, but a sudden reaction in a dog after any eye medicine is just as urgent.

Other antibiotic eye ointments for cats

Terramycin is one of several antibiotic eye ointments and drops that vets use in cats. They differ in which bacteria they cover, and some of the others also contain polymyxin B, so the allergy warning is not unique to this product. Which one suits your cat depends on what the vet finds, and sometimes on a swab. None of them is a substitute for an exam.

Side effects

Side effects are uncommon and usually mild: brief stinging, blinking or pawing straight after application, and blurry vision for a few minutes because ointment is greasy. More redness, swelling or itching around the eye can mean the pet is sensitive to the product. If the eye looks worse after you start, stop and call the vet before the next application.

How to apply Terramycin for cats and dogs

How much to use, how often and for how long depend on the animal and the problem, so follow the instructions your vet gave for your pet. The technique is the same every time:

1. Wash your hands.
2. Wipe away discharge with a clean cotton pad dampened with warm water, working from the inner corner outward. Use a fresh pad for each eye.
3. Settle your pet. Sit a cat on your lap facing away from you, or wrap it in a towel with just the head out. Stand a dog with its back end against a wall or your legs. A second person helps.
4. Rest the hand holding the tube on the top of the head, so it moves with your pet if they flinch. With your other hand, gently pull the lower eyelid down to make a small pocket.
5. Squeeze the amount your vet directed into the pocket. Do not let the tip touch the eye, the lids or your fingers.
6. Let go and allow your pet to blink, which spreads the ointment across the eye.
7. Replace the cap, wash your hands and give a treat.

If your pet is on more than one eye medicine, ask the vet in what order to give them and how long to wait between them. If your pet rubs at the eye, ask about a cone collar. Give the full course your vet set, even if the eye looks better sooner, and do not keep leftovers for next time.

An older cat with arthritis may object to being held firmly, so support the body and keep the neck in a natural position. If you cannot get the ointment in reliably, tell the clinic. The staff can show you, or the vet can suggest another form.

Missed or extra applications

If you miss an application, phone the clinic and ask what to do. Do not apply extra to catch up. If your pet has licked or swallowed ointment, or a pet has chewed the tube, call your vet or an animal poison control line for advice.

Pets who should not have it

Terramycin is not for a pet that has reacted to oxytetracycline, another tetracycline, polymyxin B or a previous eye ointment, or for an eye that has not been examined for the current problem. Ask the vet before using it in a pregnant or nursing animal. Tell the vet about every other medicine and supplement your pet takes, including other eye drops.

Questions to ask the vet

• What is causing the eye problem, and is an antibiotic the right treatment for it?
• Has the eye been checked for an ulcer, dry eye and raised pressure?
• When should the eye look better, and when do you want to see it again?
• What should make me stop and call you?

Call the vet today if

• Your pet shows any sign of an allergic reaction after an application: vomiting, facial swelling, trouble breathing, weakness or collapse. This is an emergency.
• The eye is held shut, or your pet is squinting or rubbing at it
• The eye looks cloudy, blue, bulging or larger than the other
• The pupils are different sizes, or your pet seems to have lost vision
• There is blood in or around the eye, or the eye has been injured
• Discharge is thick, yellow or green
• The eye is no better after two or three days of treatment, or is getting worse

Eyes change fast. A painful, cloudy or suddenly blind eye is a same-day problem at any age.

This page is general educational information about an animal medicine, not veterinary advice, and it does not endorse any product. Eye problems in older dogs and cats can threaten sight quickly and often are not simple infections. Whether Terramycin is appropriate, and how it should be used, is for your veterinarian to decide after examining your pet's eye.