Written By Emily Bayne
Published: 10/06/2020Updated: 09/14/2021
Terramycin for Dogs | Wag!

Terramycin is a prescription tetracycline antibiotic that treats various bacterial infections. This broad-spectrum antibiotic is effective against many common types of bacteria including stomach bugs like E. coliand E. histolytica, bacteria that cause conjunctivitis, and the germ responsible for spotted fever. 

Tetracyclic antibiotics like Terramycin hinder bacteria’s ability to synthesize proteins and reproduce, preventing them from spreading to other healthy cells and tissues. Additionally, oxytetracycline (Terramycin’s active ingredient) disrupts the cell barrier, causing the intracellular structures inside the bacteria to escape.


Terramycin is available in 4 forms: oral liquids, capsules, injectable liquid, and eye salve. Keep in mind dosage guidelines vary depending on the animal’s history, pre-existing conditions, and the prescribing condition.  

  • Capsules and liquid suspensions: 10 milligrams per pound of body weight by mouth
  • Intravenous injection: 5 milligrams per pound of body weight
  • Ophthalmic ointment: 3.5 milligrams to 5 milligrams, 2 to 4 times daily

Dosage instructions

Give oral forms of Terramycin for dogs either an hour before feeding or two hours after feeding. When administering Terramycin ophthalmic ointment, use your finger to gently open the lower eyelid and smear a small amount onto the inside of the lid. Be careful not to scratch your pet’s eye when applying this medication. 


A study from the 1950s found that Terramycin virtually eradicated the spread of E. histolytica in an outbreak of confined individuals. 

A separate study of canines with a tick-transmitted bacterial infection called ehrlichiosis found the active ingredient in Terramycin to be comparable to doxycycline, with a 100% success rate for the study group.

Terramycin ophthalmic ointment was an effective and long-lasting antibiotic ointment in a more recent study of 10 Beagles. Findings from this study detail that concentrations of oxytetracycline left in the dog’s tear duct 12 hours post-treatment were still much higher than the threshold dosage needed to kill bacterial pathogens. 

Active ingredients in Terramycin


Side effects

Typically, Terramycin doesn’t cause adverse side effects besides nausea and vomiting, though some dogs are more sensitive to antimicrobial drugs. Drug manufactures note that this medication can sometimes cause: 

  • Change in tooth color

  • Rash

  • Change in appetite

  • Stomach upset

  • Liver and kidney damage

  • Digestive problems


Terramycin can cause flare-ups in canines with colitis and enteritis because it eliminates colonies of beneficial bacteria as well as bad bacteria. Some vets recommend giving dogs prone to digestive problems a probiotic supplement while on antibiotics. 

Dogs with liver disease or low liver function should have regular check-ups and blood tests when on this medication. In humans, tetracycline antibiotics can elevate enzyme and bilirubin levels, and cause steatosis of the liver. 

Taking this medication too often can also cause certain bacteria strains to mutate and make dogs less responsive to antibiotics. 

Drug interactions

Be aware that there are medicines that interact with Terramycin for dogs. Let your vet know if your dog takes any of these medicines and supplements: 

  • Digoxin

  • Other antibiotics

  • Anticoagulants

  • Aminolevulinic acid

  • Methoxyflurane

  • Systemic retinoids

  • Medications or supplements containing Strontium ranelate

  • Certain multivitamins

Allergic reactions and sensitivity

Antibiotics are a common cause of drug reaction in canines and humans. Mild reactions usually manifest as one or more of the following symptoms: 

  • Gnawing at the paws

  • Excessive scratching

  • Skin redness

  • Rash

A more serious reaction, called anaphylaxis, can sometimes occur too. Symptoms that distinguish anaphylaxis from other allergic responses are:

  • Swelling of the face, tongue, or throat

  • Loss of consciousness

  • Trouble breathing

  • Shallow breathing

  • Abnormal heart rate

  • Rapid onset of symptoms

Frequently asked questions

Should I continue to give Terramycin for dogs after their symptoms resolve?

Yes. Give this medicine according to the vet’s orders until there is no more left in the bottle. 

Should my dog avoid certain foods while taking Terramycin?

Calcium, iron, and zinc can all interfere with the absorption of Terramycin. The chemicals in Terramycin cling to these molecules which inhibit the body from metabolizing the medicine fully. Avoid giving your dog foods high in these minerals 2 hours before or after this medication.  

Is Terramycin safe for nursing dogs?

Even though low concentrations pass into the milk, antibiotics are generally safe for breastfeeding mammals and their offspring. Terramycin is often given as a treatment for mastitis, or milk duct infection. 

Does Terramycin cure viral infections?

Antibiotics target the structures in bacteria responsible for protein synthesis since viruses don’t contain these structures; antibiotics are completely ineffective against them. 

How do dogs get a bacterial infection?

Bacteria can enter a canine’s body in numerous ways. Dogs can pick up bacteria from eating spoiled food or feces, swimming in bacteria-laden water, or from walking on a dirty surface with a cut on their paw. 

Can I catch a bacterial infection from my dog?

You can absolutely contract a bacterial infection from your dog. Make sure you’re using proper hygiene techniques when picking up after your dog and sanitize your hands before and after cleaning your pet’s wounds. 

Will Terramycin work for dogs with fungal infections?

No, only antifungals are effective against fungal pathogens.

Bacterial infections can be expensive to treat. If you suspect your dog has a bacterial infection, start searching for pet insurance today. Brought to you by Pet Insurer, Wag! Wellness lets pet parents compare insurance plans from leading companies like PetPlan and Trupanion. Find the “pawfect” plan for your pet in just a few clicks!

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