Antibiotics can be valuable options to treat your sick dog. However, antibiotic resistance when antibiotics cannot kill germs  — is a real problem. Because of this issue, veterinarians try treatments in a certain order, avoiding antibiotics when they can.  But this isn’t always possible, as some infections and conditions require these types of medications in order to be properly treated. Metronidazole (Flagyl) is a commonly prescribed antibiotic for dogs with diarrhea and other gastrointestinal problems. Since this is a “human medication,” you may be concerned about how it might affect your pet. In this article, we’ll address when metronidazole is used for dogs, possible side effects, and alternative available options. 


Metronidazole (brand name Flagyl®) is an antibacterial and antiprotozoal agent used in the treatment of certain anaerobic bacterial and protozoal infections, such as those caused by Giardia and Trichomonas. It is often used to treat diarrhea and other intestinal problems. The use of metronidazole to treat Giardia infections and most other infections in dogs and cats 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.

Metronidazole is a prescription antibiotic used to treat many types of infections in humans. It works by stopping bacteria or parasites from growing and multiplying. Metronidazole can also reach the central nervous system and bones, making it helpful for brain, spinal cord, and bone infections. 

Uses/benefits of Flagyl For Dogs

Veterinarians use metronidazole as an off-label medication since it is not FDA-approved for dogs. Metronidazole is commonly prescribed to treat infections that cause diarrhea. It is also sometimes used to treat dental infections and inflammatory bowel disease (IBD). Metronidazole is not safe in pregnant dogs, as it can cause birth defects to unborn puppies. This medication is also not safe for nursing dogs, as it passes into breast milk and can be harmful to young puppies. Lastly, it is not the best option to give metronidazole to dogs with seizures or kidney or liver problems. 

Metronidazole treats bacterial infections and some parasites, so it is prescribed to treat a variety of conditions and to relieve their symptoms. It’s often used to treat:

  • Giardia (and other parasites)
  • Inflammatory Bowel Disease (IBD)
  • Oral and dental infections
  • Other bacterial infections that cause diarrhea or sepsis, abscesses, meningitis

Features of Flagyl For Dogs

Metronidazole (also known by the brand names Flagyl, Metizol, Protostat, Metrogel) is a strong antibiotic primarily used as an antidiarrheal to treat inflammation of the large intestine. It’s also used for other illnesses and conditions in dogs, cats, and horses, as well as to treat bacterial infections in humans. It is often prescribed in combination with other antibiotics.

Metronidazole is a prescription-only medication that can be taken orally or used topically, depending on the illness being treated. The U.S. Food and Drug Administration has not yet approved metronidazole for veterinary use (it is approved for human use), but veterinarians often prescribe it for their canine and feline patients. Many of the parasites and bacteria that make us sick also affect our pets, and this is one human medication that can often help them.

Metronidazole Side Effects

  • Most common: clinical signs related to the bad taste or GI upset.
  • Dogs and cats: excessive salivation, gagging, regurgitation, pawing at the mouth, nausea, vomiting, and decreased appetite are the most frequent complaints.
  • Less common or rare: diarrhea, depression, lethargy, weakness, low white blood cell count, liver failure and blood in the urine, or dark urine due to pigment changes. Neurologic signs may be seen after accidental overdose or, more commonly, with long-term moderate-to-high-dose therapy as to treat difficult bacterial infections. Signs often begin seven to 12 days following the start of treatment.
  • Horses: side effects are not associated commonly with metronidazole. The major problem with using this drug is its bad taste. Many horses stop eating when this drug is mixed with feed and a reliable method of administration must be found.


  • Metronidazole causes birth defects in laboratory animals. It should be avoided in pregnant animals, especially in the first trimester. Some metronidazole is excreted in breast milk and it should not be used in lactating animals.
  • Metronidazole should not be used in young puppies and kittens.
  • Metronidazole should be avoided or used with caution, at reduced doses, in animals with kidney or liver disease.


  • Drug Name: Metronidazole for Dogs and Cats
  • Common Name: Flagyl®, Metizol®, Protostat®, Metrogel®
  • Drug Type: Antibiotic, antiprotozoal
  • Used For: Prevention and treatment of bacterial and parasitic infections
  • Species: Dogs, Cats
  • Administered: Tablet, Oral liquid, Injectable
  • How Dispensed: Prescription only
  • FDA Approved: No

Prices of Flagyl For Dogs

$25.16 – $69.95 

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

error: Content is protected !!