Metronidazole

Updated on September 10, 2024

Metronidazole is an antibacterial and antiprotozoal medication.

Metronidazole

Summary

Used For:

Antibiotic and antiprotozoal medication. Used for susceptible bacterial and parasitic infections; its use for non infectious, acute diarrhea is controversial

Brands: Flagyl®

Species: Dogs, cats, horses, rabbits, rodents, small mammals, ferrets, birds, horses, amphibians, reptiles.

Drug type: Antibiotic

Prescription required: Yes

Pregnancy and lactation: Not recommended for use in pregnant or lactating animals.

Side effects:

Vomiting, diarrhea, decreased appetite, neurological changes.

General description

Metronidazole is used to treat a variety of bacterial and parasitic infections. It is effective against anaerobic bacteria, as well as protozoal intestinal parasites. Although metronidazole is frequently used for acute and chronin nonspecific diarrhea in dogs, evidence to support this use is conflicting3 and the drug may have a potentially significant and sustained detrimental impact on the GI microbiota. [Buy Metronidazole now on Petco.](https://www.petco.com/shop/en/petcostore/brand/metronidazole) A prescription from your veterinarian may be needed to purchase.

Uses

Gastrointestinal infections, systemic infections with anaerobic bacteria, treat infections caused by Giardia, Trichomonas, and Balantidium coli

How it works

Metronidazole works by interacting with the DNA of susceptible bacteria and protozoal organisms, thus causing the death of the infectious cell. It also reduces cell-mediated immunity, thereby helping with the treatment of inflammatory bowel disease.

Dosage

• **Dogs**: 10-15 mg/kg for susceptible bacterial infections, 25 milligrams per kilogram for giardia by mouth every 8-12 hours. • **Cats**: 10-15 mg/kg for suspectable bacterial infections, 25 milligrams per kilogram for giardia by mouth every 12-24 hours; Trichomoniasis 30 – 50 mg/kg PO twice daily for 3 to 14 days • **Horses**: 15 milligrams per kilogram by mouth every 8-12 hours. • **Ferrets**: 10-30 milligrams per kilogram by mouth every 12-24 hours. • **Birds**: 10-50 milligrams per kilogram by mouth every 12 hours; PROHIBITED FOR USE IN POULTRY • RABBITS, RODENTS, & SMALL MAMMALS o **Anaerobic infections (extra-label)**:  **Rabbits**: 20 mg/kg PO every 12 hours or 40 mg/kg PO q24h  **Mice**: 3.5 mg/mL in water for 5 days; Spironucleus muris infection in mice (extra-label): 10 – 40 mg/kg PO twice, 5 days apart60  **Rats**: 10 – 40 mg/rat (NOT mg/kg) PO once daily  **Guinea pigs**: 10 – 40 mg/kg PO once daily.  **Chinchillas**: Metronidazole should be used cautiously in chinchillas due to risk for reduced food intake and potential hepatoxicity.  **Gerbils, hamsters**: 7.5 mg/70 to 90 g body weight PO every 8 hours • **REPTILES/AMPHIBIANS** o **Treatment of amoebae, flagellates, and ciliates in reptiles and amphibians (extra-label)**: Typically, metronidazole 100 mg/kg PO repeated in 2 weeks or 50 mg/kg PO once daily for 3 to 5 days. o **Anaerobic respiratory infections in reptiles (extra-label)**: 20 mg/kg PO every 48 hours

Forms

Oral tablets: 250 and 500 milligrams, Oral Capsules: 375 milligrams. May be compounded into an oral suspension at varying concentrations.

Storage information & handling

Tablets should be stored in a tight, light resistant, and childproof container at room temperature. Refrigerate oral suspension.

What results can I expect?

Resolution of the infection.

Missed Dosage

It is best to give the medication at the same time every day without skipping doses. If you miss a dose, give it as soon as possible. If it is almost time for the next dose, skip the one you missed and go back to the normal schedule. Do not give 2 doses at the same time.

Overdose / acute toxicity

In cases of overdoses, decreased appetite, vomiting, depression, dilated pupils, nystagmus, ataxia/staggering, head tilt, joint knuckling, disorientation, tremors, decreased heart rate, stiffness, and seizures may be seen. If you think your pet has had an overdose, seek veterinarian care immediately.

Side effects

• Common side effects include nausea, decreased appetite, vomiting, and diarrhea. Give with food to reduce risk of GI upset. • At higher doses, neurologic signs (ataxia/staggering, joint knuckling, Head tilt, dilated pupils, nystagmus) may be observed. Seek veterinary care if concerned.

Contraindications

• Previous sensitivity • Debilitated animals • Liver disease • Pregnant or lactating animals • Prohibited for use in food animals by the FDA

Drug interactions

Consult your veterinarian before using metronidazole with any other medications, even vitamins and supplements The following medications may especially • CYCLOSPORINE: • MYCOPHENOLATE • PHENOBARBITAL • QT PROLONGATION DRUGS (eg, amiodarone, cisapride, procainamide, quinidine, sotalol) • WARFARIN

Precaution

Do not use in severely debilitated, pregnant, or lactating animals. Prohibited by the FDA for use in food animals. Use caution for use in animals with liver dysfunction.

Laboratory considerations

May falsely decrease AST (SGOT) and ALT (SGPT). • Metronidazole can interfere with measurement of serum triglycerides.

Sources

Plumb's Veterinary Handbook
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Disclaimer

The information contained on this page is for educational purposes only. This medication should only be given under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.