405 Heron Drive Suite 200
Swedesboro, NJ 08085
Ph 800.331.8272

Ronidazole for Veterinary Use

by Barbara Forney, VMD

Basic Information

Ronidazole is a nitroimidazole antibiotic/antiprotozoal from the same family as metronidazole. It is toxic to protozoa by virtue of the disruption of protozoal DNA. Ronidazole is considerably more effective than metronidazole in treating trichomonal infections. There is also some research that indicates that it may be effective to treat Giardia in dogs.

Although drugs from this family are used to treat trichomonal infections in birds, it is important not to use ronidazole in food animals due to concerns regarding carcinogenicity. Ronidazole is well absorbed following oral administration. It is not approved for either human or animal use in the United States therefore it is only available through compounding pharmacies.


Ronidazole is an anti-protozoal drug that is effective against Tritrichomonas foetus in the cat. Although the efficacy has been demonstrated in multiple studies, there is relatively little published information on this drug. Ronidazole is given orally for 14 days. It is compounded into capsules because, like metronidazole, it is very bitter tasting.

Side Effects

  • The most-common side effects are anorexia, nausea, and vomiting.
  • Rare, but more serious side effects are neurologic and may include weakness, ataxia, twitching, and seizures. Usually neurologic signs will resolve by simply discontinuing the drug, but in some instances they may worsen initially before improving. In these cases it may take as long as four weeks before there is a complete resolution of clinical signs.


  • Ronidazole is considered to be possibly carcinogenic. The FDA prohibits its use in food animals. Human contact should be minimized (always wear gloves).
  • In order to avoid neurotoxicity it is important to work with an accurate body weight. The dosage may be further reduced in kittens.
  • Ronidazole is teratogenic and should not be used in pregnant animals.

Drug Interactions

  • Most of the drug interactions listed for Ronidazole are extrapolated from experience with Metronidazole.
  • Ronidazole may increase the levels of the following drugs: Cyclosporine, systemic Tacrolimus, Fluorouacil, Lithium.
  • Cimetidine, and Ketoconazole decrease the metabolism of Ronidazole, and could increase the incidence of neurotoxicity.
  • Ronidazole should not be used with Oxytetracyclines, Phenobarbital, Rifampin, or Phenytoin. These drugs either antagonize or increase the metabolism of Ronidazole.
  • Alcohol should be avoided due to the possibility of a disulfiram reaction.
  • Ronidazole should be avoided in animals receiving coumarin anticoagulants due to increased clotting times.


If oral overdose is recognized promptly, gut-emptying protocols may be helpful. If neurologic signs occur, supportive nursing care may be required for some time.

Looking for Ronidazole?

We can let your veterinarian know that you are interested in our compounded Ronidazole.

Have a written prescription from your veterinarian?
Get your instant quote by chat!

Therapeutic Class


May Be Prescribed by Vets for:
Infections due toTritrichomonas foetus and Infections due to Giardia

Search for Available Dosage Forms

About the Author

Dr. Barbara Forney

Barbara Forney, VMD

Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.

She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.

Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.