By Rania Gollakner, BS, DVM, MPH

What is ronidazole?

Ronidazole (brand names: Belga®, Ridsol-S®, Ronida®, Ronivet®, Ronizol®, Turbosol®, Tricho Plus®, Trichocure®, Trichorex®) is an antiprotozoal, antiparasitic medication used to treat Tritrichomonas foetus infections in cats. It has also been used to treat trichomonas species in pet birds and to treat giardia in pet dogs and cats.

Its use in pet cats and dogs to treat parasitic infections is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label. This medication is not commercially available in the United States or Canada, however compounding pharmacies may have it available. It should not be used to treat farmed animimals.

How is ronidazole given?

Ronidazole is given by mouth in the form of a capsule or liquid. It should be given with food prevent stomach upset. Measure liquid forms carefully. Wear gloves when administering this medication, and do not open or crush capsules. Wear gloves when handling feces, urine, vomit, saliva, or cat litter.

This medication should take effect within 1 to 2 days, and improvements in clinical signs should follow.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. If you are giving this medication once daily and it is within 12 hours of the next dose, skip the missed dose and wait for the next scheduled time.

Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects may include vomiting or decreased appetite. Serious side effects may include tremors, severe tiredness, lack of appetite, incoordination, dizziness, fever, seizures, weakness, collapse, or abnormal behavior.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Do not use ronidazole in pets that are allergic to it or other nitroimidazoles such as metronidazole. Dogs given this medication long term (for 2 years) had signs of testicular toxicity. It should be used cautiously in pets with seizures and very cautiously in pregnant animals; the benefits should outweigh the risks. If use in lactating animals is needed, use a milk replacer.

This medication is potentially carcinogenic to humans as it has been shown to cause cancer in mice, and has been shown to increase the rate of certain cancers in rats. As a precaution, wear gloves when administering this medication.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with ronidazole: cimetidine, cyclosporine, fluorouracil, ketoconazole, lithium, oxytetracycline, phenobarbital, phenytoin, rifampin, tacrolimus, or warfarin.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

There is no specific monitoring that needs to be done while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working. Monitor your pet for serious side effects. Your veterinarian may check a polymerase chain reaction (PCR) test for the parasite although this test is not always accurate.

How do I store ronidazole?

Store this medication in the freezer in a tight container and protect from light, unless otherwise instructed on the label.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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