Metronidazole for Dogs

Metronidazole is an antibiotic primarily used to treat diarrhea in dogs caused by inflammatory bowel disease (IBD). Metronidazole for dogs is taken orally. It's effective against Giardia infections and certain vaginal infections as well as bacteria andparasites.

Metronidazole for dogs is available by prescription only and is designated as an off-label use of the drug. Certain human medications have been found to be effective in dogs, although they have not been officially tested for use in animals by the FDA. It's important to follow your vet's instructions because they may differ from those on the medication label. 

Cost

Metronidazole for dogs is available in 250- and 500-milligram tablets and is widely available at pharmacies and online retailers. An intravenous liquid is available for veterinarians to administer in their offices. This drug is not available without a prescription.

The average retail cost of metronidazole for dogs is $19 for a course of treatment, with a low of $13 and a high of $28. Discounted pharmacies offer prices averaging $9. The cost of IV medication and administration will vary by vet. 

Dosage

Metronidazole for dogs is available as tablets or liquid. Most prescriptions are for the tablet form.

The dosage will vary depending on the condition and your dog's weight. The following dosages are general guidelines — your vet will recommend the right dosage for your dog.

• Bacterial infections: 22 milligrams per kilogram of body weight
• Giardia infections: 25 milligrams per kilogram of body weight
• Parasitic infections: 66 milligrams per kilogram of body weight

The first dose of metronidazole is typically higher (up to twice the normal dose).

Dosage Instructions

This medication should be given with food. If administering the liquid, shake the bottle well before giving it to the dog. The tablet is bitter, so it’s best not to crush it. 

The liquid form is meat-flavored to make giving it easier for both you and the dog. Expect some spitting of the liquid – do not give more than the recommended dose at one time.

Efficacy

A study reported by the National Institutes of Health from the Journal of Veterinary Medicine examined the effectiveness of metronidazole for dogs in treating diarrhea. The study found that metronidazole shortened the diarrhea duration to approximately two days, while the control group that didn’t receive the drug took almost four days to recover.

Metronidazole has also been effective in treating organisms that live without oxygen, known as anaerobes. These are often found in abscesses and in the pus from infected lungs (empyema). Because of this characteristic, the drug is prescribed for dental infections as well. 

Other conditions that this medication is used for include:

• Abdominal abscesses
• Peritonitis (infection of the wall of the abdomen)
• Urinary tract infections
• Periodontitis (gum infection)
• Otitis media (ear infection)
• Bone infections
• Arthritis

Because metronidazole is able to pass through the blood-brain barrier, it can be used to treat meningitis. Also, it is sometimes used as an adjunct drug in radiotherapy treatment of solid tumors.

Side effects

Common side effects with metronidazole are:

• Nausea and vomiting
• Secondary diarrhea
• Drooling
• Gagging and regurgitation
• Fatigue
• Loss of appetite
• Urine discoloration
• Fever

More serious reactions to metronidazole for dogs, in cases where the use of the drug is long-term or at high doses, have been reported:

• Irregular heartbeat
• Slow heartbeat
• Tremors
• Seizures
• Muscle spasms
• Dilated pupils
• Eye twitching

In rare cases, dogs receiving this medication suffer neurotoxic symptoms, including paralysis in the legs. Also rare but sometimes present is a skin disorder known as cutaneous vasculitis. The vasculitis exhibits scaling, hair loss, bruising, swelling, and skin bumps.

These serious side effects constitute an emergency. If they appear, call the veterinarian immediately or take the dog to an emergency vet clinic.

Considerations

This medication is considered safe, but it should not be given to puppies or pregnant dogs, especially in the first trimester. Also use caution in dogs who are nursing or have kidney or liver disease, a low white blood count, or a seizure disorder.

It’s important to provide plenty of fresh water when your pup is taking this medication to avoid dehydration. 

Drug Interactions

Metronidazole may interact with the following medications:

• Certain chemotherapy drugs (cyclophosphamide, BCNU)
• Gastroprotectants (cimeditine)
• Immunosuppressants (cyclosporine)
• Barbiturates/anticonvulsants (phenobarbital, phenytoin) 
• Anti-clotting medication (warfarin)

Allergic Reactions

Metronidazole for dogs doesn't usually cause allergic reactions. Symptoms of mild allergies to the drug include:

• Hives
• Rash
• Fast heartbeat
• Shortness of breath

At the first sign of an allergic reaction, stop the medication and contact your veterinarian. 

Frequently asked questions

How do I store metronidazole?

This medication should be stored in an airtight container, protected from light and moisture at temperatures below 86 degrees Fahrenheit. If using the liquid version, store it in the refrigerator between doses.

What should I do if I miss a dose?

If you miss a dose, give it as soon as you remember it. If it’s close to the time for the next dose, don’t give the missed dose, but resume dosing with the next scheduled one. Don't double up doses for this medication as overdosing can cause severe, dangerous reactions.

How long will my dog be on metronidazole?

The usual treatment period is 5 to 7 days. However, your veterinarian may wish to extend that time if the infection is not responding as well as expected. It’s important to remember to give all of the doses to your dog on a schedule. Do not stop before the prescribed time is up, even if your dog seems to be feeling better.

Can I get metronidazole over-the-counter at a drugstore?

Metronidazole for dogs is only available with a prescription from your veterinarian.