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Key takeaways
The dosage of metronidazole depends on the type of colitis, the length of the colitis, and the dog’s weight.
Dog owners should never calculate the metronidazole dosage but rely on their veterinarian’s guidance.
It can take a few days to determine whether or not the metronidazole is working for your canine.
If your dog experiences adverse reactions, such as vomiting, blood in its stools, seizures, or tremors, please take it to a veterinary hospital.
Alternatives to metronidazole include other antibiotics, steroids, supplements, and diet changes.
Metronidazole (Flagyl) is an antibiotic that the U.S. Food and Drug Administration (FDA) approves for human use to treat various conditions caused by parasitic and bacterial infections. It is available in tablets, injections, creams, lotions, and gels. Metronidazole benzoate is used in veterinary medicine to treat off-label inflammatory conditions like colitis in dogs.
Metronidazole for colitis in dogs
“Metronidazole is an antibiotic that focuses on treating overgrowth of bacteria in the intestinal system,” says Dwight Alleyne, DVM, a veterinarian advisor for Betterpet.com based in Marietta, Georgia. “Colitis is often associated with overgrowth of bacteria, which is why metronidazole can be helpful.”
According to Amy Attas, DVM, the founder of City Pets Vets in Manhattan, and the author of Pets and the City: True Tales of a Manhattan House Call Veterinarian, metronidazole may be prescribed to dogs with colitis because it contains antimicrobial, anti-inflammatory, and immunomodulatory properties that can alleviate symptoms like abdominal pain and diarrhea.
Colitis, or large bowel diarrhea, can be either an acute (short-term) disease or part of a chronic (long-term) disease in dogs. It is a symptom of chronic inflammatory bowel disease (IBD), a disease with recurrent inflammation of the large intestine. Symptoms of colitis include acute diarrhea or loose bowels that may contain blood and mucus.
There are several risk factors for colitis in dogs, including:
- Stress
- Dietary indiscretion
- Trauma
- Infections (i.e., Clostridium, Salmonella, and E.coli)
- Allergic colitis
- Primary IBD
- Contact with infected dogs
Depending on what type of colitis your dog has, it can last a few days (acute colitis) or several weeks (chronic colitis).
The metronidazole dosage for diarrhea in dogs varies depending on several factors. In some cases, alternatives to this drug may be more beneficial for canines with colitis.
Metronidazole for colitis in dogs dosage
Several factors affect how veterinarians administer metronidazole to dogs with colitis. “The main factors that influence the proper dosage for metronidazole include the dog’s size, the primary cause of the colitis, and how long the condition has been going on,” Dr. Alleyne says.
How much metronidazole can I give my dog for colitis?
One factor that determines how much metronidazole is given is your dog’s weight. Dr. Alleyne advises against pet owners calculating dosage on their own. “Dosage should only be calculated under the guidance of a veterinarian,” Dr. Alleyne explains. “The average dose is around 7 milligrams (mg) per pound.”
Dr. Attas is also against pet owners’ self-calculating metronidazole doses for their dogs, as this drug can cause serious side effects. “This is not a benign (harmless) drug,” she says. “It can cause liver damage, liver failure, seizures, and central nervous system problems.”
The other potential side effects of metronidazole may include the following:
- Nausea
- Vomiting
- Diarrhea
- Regurgitation
- Decreased or lack of appetite
- Tiredness
- Drooling
Veterinary use of metronidazole can also cause neurological symptoms, such as:
- Lack of muscle control or coordination
- Seizures
- Tremors
- Vomiting
- Eye twitching
- Weakness
These symptoms typically occur if metronidazole is given at high doses during long-term use but can occur at lower doses in some instances.
Also, be aware of potential allergic reactions that metronidazole may cause, including:
- Difficulty breathing
- Hives
- Swelling of the face
- Itching
- Skin rash
Please contact your veterinarian immediately if you notice any of these adverse reactions.
How long should I give metronidazole to my dog?
According to Dr. Alleyne, metronidazole is typically given to dogs every 12 hours for 5-7 days at an average dose of 7 mg per pound.
However, Dr. Attas says the duration can vary depending on whether or not the dog receives recurring treatment or takes the drug with a prescribed diet or supplements.
“Metronidazole is one part of effective treatment for colitis,” she says. “For some dogs, periodic treatment resolves symptoms, and diet changes and supplements effectively control symptoms.”
How do you know if metronidazole is working?
“When treating colitis, the target is for the patient to have normal bowel movements,” Dr. Attas says. According to Dr. Alleyne, it can take 2-3 days for your canine to resolve symptoms like acute diarrhea.
Just as there are clinical signs that the drug is working for your dog’s condition, it’s crucial to take note of warning signs that metronidazole is not effective for treating your canine’s colitis.
“If the patient is not eating, not feeling well, having frequent, voluminous bowel movements with mucus and blood, then the metronidazole and the treatment protocol are not working,” Dr. Attas says.
Dr. Alleyne recommends visiting your dog’s veterinarian if they have persistent diarrhea, especially if there is blood in the stools.
It is also important to mention potential drug interactions with this antibiotic, which include:
- Busulfan
- Cimetidine
- Cyclosporine
- Phenobarbital
- Warfarin
Ensure you notify your vet of any medications or supplements your dog is taking before they start metronidazole.
Alternative treatments for canine colitis
Metronidazole is not the only treatment for canine colitis. Possible alternatives your veterinarian may recommend can include the following:
- Other antibiotics: Amoxicillin, chloramphenicol, and sulfasalazine are different antibiotics that may be prescribed for colitis in dogs. These, in addition to metronidazole, can be first-line treatments for addressing IBD conditions like colitis in dogs.
- Steroids: Steroids are another type of prescription drug that may alleviate colitis symptoms. “In some cases of colitis, steroids are needed to decrease the inflammation of the colon,” Dr. Attas says. Examples of steroids that may help with canine colitis include prednisone, prednisolone, and budesonide.
- Supplements: Your veterinarian may prescribe or recommend supplements like probiotics or prebiotics to improve your dog’s gut health. “Probiotics can help by restoring a balance of good bacteria in the gastrointestinal system,” Dr. Alleyne says. Prebiotics can also promote good bacteria in your dog’s gut. In addition to prescriptions, pre-and probiotics are also available over the counter as powders, capsules, and chews.
- Diet changes: Changing your dog’s diet may also benefit your dog’s colitis. “Under veterinary supervision, slowly change your pet’s diet to one labeled for gastrointestinal upset,” Dr. Attas says. “Some cases of colitis are due to food allergies. Elimination diets may be helpful.”
“Metronidazole is a very effective medication when used properly,” Dr. Attas says. “However, excessive use or higher doses can cause severe medical problems. It should only be used under a veterinarian’s supervision.”
Sources
- Ulcerative colitis, National Institute of Diabetes and Digestive and Kidney Diseases (2020)
- Colitis in dogs, VCA Animal Hospitals (n.d.)
- Colitis in dogs: Signs, symptoms, treatment, American Kennel Club (2024)
- Metronidazole for dogs, Veterinary Place (2024)
- Metronidazole, VCA Animal Hospitals (n.d.)
- Metronidazole capsules or tablets, Cleveland Clinic (2024)
- Colitis in small animals, Merck Manual Veterinary Manual (2020)
- Probiotics for dogs, American Kennel Club (2024)
