Flagyl, brand of Metronidazole for dogs

Metronidazole For Dogs – All You Need To Know

Edited by Dominique Martin

Dogs are inquisitive by nature. They like to explore new objects and sometimes lick or chew them. Although most of the time this behavior will not impact your dog’s health, they can occasionally pick up bacterial infections if they eat something they are not supposed to.

Bacterial infections can be dangerous and may leave your dog bedridden with an upset stomach (especially infections of the gut or the large intestine).

Pet parents often wonder if Flagyl, a brand name for the antibiotic Metronidazole, can be given to their dogs. This is because Metronidazole is one of the most commonly used antibiotics for humans.

Antibiotics are commonly used in pets and humans to treat infections. There are many different types and brands of antibiotics, so knowing information about each one is important.

Nevertheless, here’s the low down on using Metronidazole for dogs.

What is Metronidazole?

Metronidazole is a multipurpose antibiotic drug that is commonly used for treating a variety of bacterial infections. This drug targets certain parasites and anerobic bacteria, but it will not work on viruses. It is commonly used to treat diseases of the digestive system and infections in humans. 

In dogs, Metronidazole is also used for treating a wide range of infections including Entamoeba, Trichomonas, Balantidium Coli, and Giardia. Depending on whether it is a bacterial infection or a protozoan one, your vet may prescribe Metronidazole along with other antibiotics as a combination of drugs.

Blackboard with the chemical formula of Metronidazole

Advantages of Using Metronidazole for Dogs

One of the advantages of using Metronidazole in dogs is that it can effectively bypass the blood-brain barrier which is not common with other antibiotics. This makes it a very effective and successful treatment against infections of the central nervous system, bone infections, and dental infections in dogs.

Although Flagyl is FDA approved for human use, it is not FDA approved for veterinary use. Still, it is prescribed for dogs for a number of different purposes. For this reason, it is important that you know the uses, side effects, and other important information about Metronidazole.

What Is the Purpose for Using Metronidazole?

Metronidazole may be used as a standalone therapy or in combination with other antibiotics for treating a range of bacterial and parasitic infections in dogs. It has excellent bioavailability in the dog’s body within just an hour of use, making it one of the best antibiotics for your pet if prescribed by a veterinarian.

For example, it can treat Giardia, a parasite that is transmitted to your dog from water, food or from the soil. Giardia can trigger constant diarrhea and occasional vomiting in your pets. Metronidazole is a very effective therapy against Giardia and other protozoan parasites.

Other than this, it can be used for treating bowel disease, unexplained diarrhea, anerobic bacterial infections that can lead to sepsis, dental infections, and tetanus.

Metronidazole also has an immune modulating effect and may be used in conjunction with other medications to treat inflammatory bowel disease.

How Metronidazole For Dogs Work?

Like most antibiotics, Metronidazole targets the bacterial cell by entering it and preventing the DNA from replicating. This stops the bacteria from duplicating further in the dog’s body.

When used to treat infections of the central nervous system, it is able to penetrate into damaged tissue that does not have proper oxygen supply or circulation. It targets the pathogens which are known to thrive in such anaerobic environments by preventing them from repairing and replicating.

sick dog that could use Metronidazole

Is Metronidazole Safe For My Dog?

Metronidazole is generally well tolerated in your pet’s body and is considered safe for veterinary use. However, it is a prescription drug that does come with a risk of possible side effects and there are certain conditions that it must not be used in.

For example,

  • This medication should be given to puppies.
  • It should not be given to pregnant dogs
  • Metronidazole may not be suitable for dogs with liver disease, kidney disease, seizures and neutropenia (extremely low neutrophils in the blood)

Also, antibiotic therapy of any type should be closely monitored by your vet because there is a significant possibility of the infection recurring with a resistant strain of bacteria or pathogen. For this reason, the dosage and the treatment duration are extremely important.

Additionally, using Metronidazole for extended periods of time may cause severe side effects in your dog.

What is The Right Dosage of Metronidazole For Dogs?

The right dosage of Metronidazole for dogs will depend on different factors including your dog’s weight, age, and the condition being treated.

For most conditions, however, the normal dosage is 5mg-20mg/kg of the dog’s weight. This is divided into timed multiple doses throughout the day to keep the level of the antibiotic constant in the blood.

The most important aspect of treatment with Metronidazole in dogs is the duration of therapy. Depending on the severity of the condition, your vet may prescribe it for three to seven days.

Are There Any Side Effects That I Need to be Aware of?

Like most antibiotics, Metronidazole can cause some mild side effects as the dog’s body tries to adjust to the medication. These usually subside in a day or two and should not persist. Common side effects include:

  • Nausea
  • Excessive Drooling
  • Diarrhea
  • Fatigue
  • Loss of appetite
  • Gagging

Close-up portrait of a labrador dog a with a sick face

If any of these symptoms continue unabated, then contact your veterinarian. In rare cases, Metronidazole can also cause some very serious side effects, especially with prolonged treatment. These may be fatal for your dog if left untreated. If these occur, it is important to contact your vet immediately.

Serious symptoms to look out for include:

  • Allergic reaction (hives, rash, difficulty breathing)
  • Paralysis
  • Stiffness in limbs
  • Seizures
  • Unexplained tremors
  • Pupil dilation
  • Prolonged increased heartbeat

If I Missed a Dose, Can I Give a Double Dose to Make up For it?

We all occasionally forget to take our meds on time. However, you must never give your dog a double dose to compensate for a missed one. The best course of action in such a scenario would be to skip that dose entirely and then adhere to the regular dosage schedule from the next dose onwards.

To ensure that you give your dog the doses on time, which is crucial in an antibiotic therapy, you can use a pill box or a reminder.


When used correctly, Metronidazole is a very useful antibiotic medication in dogs. The caveat is that you must be aware of the exact dosage, the possible risks and the exact duration of treatment.

If you have any doubts, speak to your vet first before use.