Metronidazole for dogs: What you need to know

In this article:

• What is metronidazole?
• Uses of metronidazole in dogs
• Metronidazole dosage for dogs
• Contraindications
• Side effects
• Metronidazole alternatives for dogs
• FAQs

In this article

• What is metronidazole?
• Uses of metronidazole in dogs
• Metronidazole dosage for dogs
• Contraindications
• Side effects
• Metronidazole alternatives for dogs
• FAQs

Metronidazole is an antibiotic that treats bacterial and parasite infections in dogs. Veterinarians are likely to give it to a sick dog with gut problems or diarrhea caused by Giardia, amoebas, or bacteria. Metronidazole can also be used for central nervous system, skin, or oral/dental infections, or used to prevent infections after surgery. Dosages are based on weight, but veterinarians also consider the type of infection in deciding what dose to prescribe and how long treatment should last. 

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What is metronidazole?

“Metronidazole is an antibiotic medication commonly prescribed for dogs,” says Kathryn Rosalie Dench, DVM, a veterinary surgeon, adviser, and writer at GentleDog Trainers, a recognized authority in pet care. “It belongs to a class of drugs known as nitroimidazoles and is effective against a variety of bacterial and protozoal infections.”

Along with being prescribed for dogs, metronidazole can also be used for humans, horses, and cats. Metronidazole has not been FDA approved for small animals, but it can help with various conditions.

Uses of metronidazole in dogs

Metronidazole is an antibiotic that can be used for several different reasons. 

“It is commonly used to treat gastrointestinal infections caused by certain bacteria or parasites, such as Giardia or Clostridium,” Dr. Dench says. 

Metronidazole does best with anaerobic bacteria, meaning germs that thrive without oxygen, so they do particularly well helping infections that cause diarrhea. Metronidazole also has anti-inflammatory effects within the gastrointestinal system and can help with diarrhea and symptoms of inflammatory bowel disease.

If your dog has any infections in their mouth, an abscess, or an infection in any other areas of the body, it’s also possible your veterinarian may prescribe metronidazole to treat the infection and prevent it from spreading further. 

Metronidazole dosage for dogs

“The proper dosage of metronidazole for dogs depends on the type and severity of infection being treated,” says Ellen Russell, DVM, MPH, a veterinarian at The Malamute Mom. “Generally speaking, it is recommended that a dose of 5–10 mg per pound of body weight (10–25 mg/kg) be administered two times daily for five to seven days.”

The dosage and length of treatment depend on the condition metronidazole is being used to treat. Because the dose is based on the weight of the dog, small dogs will get lower doses while larger dogs will have higher doses. Doses may need to be reduced for dogs with liver problems. Dr. Russell also warned pet parents, “It is important to never exceed the prescribed dosage, as this can be harmful to the dog.”

Who should not use metronidazole for dogs

Some dogs may not be able to take metronidazole. They include:

• Dogs with a known sensitivity or allergy to the medication 
• Dogs with certain neurological diseases 
• Dogs that are pregnant or lactating
• Dogs on medications that are contraindicated

Side effects of metronidazole for dogs

Side effects of metronidazole in dogs are uncommon and can include reduced appetite, vomiting, and tiredness. Some dogs are more sensitive to metronidazole and can exhibit neurologic changes while taking metronidazole. These include staggering, rapid eye movements, head tilt, and weakness. These side effects are more likely with higher doses and longer durations of treatment and should be reported to your vet immediately if noted.

Signs of metronidazole overdose in dogs

Metronidazole toxicity may occur if your dog accidentally gets too much metronidazole. Since metronidazole can pass through the blood-brain barrier, it’s possible that many of these side effects may be neurological in nature. Signs of overdose may include the following symptoms:

• Reduced appetite
• Refusal to eat
• Vomiting
• Disorientation
• Ataxia (difficulty balancing and walking)
• Joint knuckling (walking on the tops of the paws)
• Head tilt
• Rapid eye movements (nystagmus)
• Tremors or seizures
• Rigid body movements

If you notice these symptoms, it’s essential to contact a veterinary professional immediately. 

Metronidazole alternatives for dogs

If your dog has had an allergic reaction to metronidazole, drug interactions, or negative reactions to it in the past, your veterinarian may instead prescribe a different antibiotic. These may also come with potential side effects.

• Fenbendazole (for Giardiasis)
• Tinidazole (for amoeba infections of the gut)
• Amoxicillin-clavulanate, ampicillin, or tylosin (for Clostridial overgrowth)
• Sulfasalazine, tylosin, or enrofloxacin (for inflammatory bowel disease)

Natural alternatives to metronidazole

If metronidazole is being used to treat gastrointestinal disease, probiotics or fiber supplements may be used in conjunction with or in place of metronidazole. Consider switching the dog to a special diet of highly digestible food with moderate levels of fat to help reduce stool volume and bowel activity.  If metronidazole is prescribed to treat infections outside of the gut, antibiotics may truly be essential to treatment. 

Frequently asked questions about metronidazole for dogs

What does metronidazole treat in dogs? 

Metronidazole treats parasitic infections and various bacterial infections, including gastrointestinal infections, inflammatory bowel disease, intestinal inflammation, and skin infections.

How long does it take for metronidazole to work in dogs?

Vets typically prescribe metronidazole for five to seven days. Your dog should start feeling better within a few days, but it’s essential to complete the entire course of metronidazole to ensure the infection is completely resolved. 

Can metronidazole be used long-term in dogs?

It’s not recommended for metronidazole to be used long-term, as it can affect your dog’s gut health and lead to a higher risk of toxicity. It is possible your vet will extend your dog’s treatment on metronidazole if the first round does not successfully treat the infection.

Is metronidazole safe for pregnant or nursing dogs?

“It is also not recommended for use in pregnant or lactating bitches as there is a risk of fetal malformations,” Dr. Russell says.

Does metronidazole help treat upset stomach in dogs?

If your dog’s stomach is upset because of a gastrointestinal infection, metronidazole may help by curing the underlying issue. However, it is not a quick remedy to soothe their stomach or stop diarrhea.

How to store metronidazole

You don’t need to do anything special to store metronidazole. It does best at room temperature while away from light and moisture, so avoid keeping it in the bathroom.