Terramycin® for Cats and Dogs (Oxytetracycline, Polymyxin B)

PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What Is Terramycin® for Cats and Dogs?

Terramycin® ophthalmic ointment is a broad-spectrum antibiotic, which means that it can kill many types of bacteria. It helps treat eye infections, including pink eye, corneal ulcers (an open sore on the clear surface of the eye), inflamed corneas, and eyelid inflammation in cats and dogs.

Terramycin® also helps treat eye infections that result from body-wide infectious diseases, such as distemper in dogs.

Terramycin® is an FDA-approved over-the-counter (OTC) drug for animals that’s available without a prescription in all states except California, where a prescription is required by a veterinarian.

Although Terramycin® is available without a prescription for most of the United States, always consult your veterinarian before giving Terramycin® to your pet. That’s because what looks like an eye infection may actually be a severe eye condition, like eosinophilic keratoconjunctivitis, which is suspected to be caused by a virus and cannot be treated with an antibiotic. Only your veterinarian can rule out these serious conditions and accurately diagnose your pet. 

How Terramycin® Works for Cats and Dogs

The active ingredients in Terramycin® are oxytetracycline and polymyxin B.

• Oxytetracycline is an antibiotic that kills susceptible bacteria by disrupting their ability to make certain proteins that are required for the bacteria to survive. Oxytetracycline can also help heal corneal ulcers by blocking specific proteins that damage the cornea.

• Polymyxin B kills organisms by altering their cell membranes.

These active ingredients work together to kill a wide range of bacteria.

The misuse of antibiotics, including Terramycin® ophthalmic ointment, can result in the overgrowth of antibiotic-resistant bacteria.

Talk to your veterinarian if your pet’s infection does not resolve or worsens.

Terramycin® Directions for Cats and Dogs

Here are steps for safely applying Terramycin® to pets, but follow the directions on the drug label or as provided by your veterinarian.

1. Wash your hands before administering Terramycin® or any other eye medication. 

2. To avoid contamination, do not touch the applicator tip with your finger, your pet’s eye, or any other object. 

3. Apply a ¼-inch strip of ointment to the affected eye(s) two to four times per day, or as directed by your veterinarian.

   • To apply, gently pull down the lower eyelid and apply the medication into the space between the lid and the eye. The eyelid will spread the medication over the surface of the eye when your pet blinks. 

4. Gently wipe any remaining medication from your pet’s skin or face with a tissue or damp washcloth. 

5. Wait five to 10 minutes after use before applying any other eye medications. 

6. Contact your veterinarian if you have difficulty administering this medication or have any questions regarding the treatment. 

Terramycin® belongs to class of antibiotics called tetracyclines. Pregnant women and those who are sensitive to tetracycline antibiotics should use caution when handling this medication. Wearing gloves when administering Terramycin® to your pet and washing your hands afterwards can help minimize your exposure to Terramycin®.

Missed a Dose? 

If you forget a dose, apply the medication when you remember and resume your dosing schedule. 

Do not give extra or double doses. 

Possible Side Effects of Terramycin® in Cats and Dogs

Life-threatening allergic reactions can occur, especially in cats. Emergency veterinary care is often necessary.

Contact your veterinarian immediately if your pet exhibits any of the following signs:   

• Swelling of the face  

• Itching 

• Weakness 

• Vomiting 

• Difficulty breathing 

Animals typically tolerate Terramycin® ophthalmic ointment very well. However, eye irritation or redness may occur. 

Talk to your veterinarian before using Terramycin® in young or pregnant animals. Oral or injectable medications in the same class of Terramycin® (tetracyclines) can impact bone development and cause discoloration of the teeth in young, growing animals. High doses or long-term use can delay growth and healing.

Human Side Effects

This medication is not used in human medicine. Due to possible side effects, humans should never use medicine dispensed for their pets, and pets should not be given any medicine dispensed for a human’s use.

If you are allergic to tetracycline antibiotics, are pregnant, trying to become pregnant, or breastfeeding, use caution during administration to minimize your exposure to the medication or talk to your veterinarian about the possibility of administering an alternative medication to your pet.

If you accidentally ingest this medication or use it in your own eye, please call your physician or the national Poison Control Center hotline at 1-800-222-1222.

Monitoring Your Pet

No specific monitoring is required for this medication, but your veterinarian may recommend routine testing depending on your pets' individual needs, other medications they may be on, and/or the issue that initially caused your pet to be placed on this medication.

When To Call Your Vet

Call your veterinarian if any of the following apply:

• Side effects are seen (see above) 

• Your pet’s condition worsens or does not improve with treatment

• You see or suspect an overdose

• You have additional questions or concerns about the use of Terramycin®

Terramycin® Overdose in Cats and Dogs Information

Overdoses can occur if an animal eats or otherwise consumes Terramycin® ophthalmic ointment.

If this occurs, immediately contact your veterinarian or an animal poison control center. Consultation fees often apply. 

• Pet Poison Helpline® 855-764-7661 

• ASPCA® Animal Poison Control 888-426-4435

How To Store Terramycin® for Cats and Dogs

Follow these tips when storing your pet’s Terramycin®:

• Store at room temperature between 68–77 degrees F (20–25 degrees C). Brief exposure to temperatures between 59–86 degrees F (15–30 degrees C) are acceptable. 

• Keep lid tightly closed when not in use. 

• Keep out of reach of children and pets. 

• Always confirm storage requirements by reviewing the label.