Metronidazole for colitis in dogs

In this article:

• Metronidazole for colitis in dogs
• Dosage
• Missed dose
• Treatment duration
• How do you know if metronidazole is working?
• Alternatives
• When to see your vet
• FAQs

In this article

• Metronidazole for colitis in dogs
• Dosage
• Missed dose
• Treatment duration
• How do you know if metronidazole is working?
• Alternatives
• When to see your vet
• FAQs

Metronidazole (Flagyl) is an antibiotic approved by the U.S. Food and Drug Administration (FDA) for human use to treat various conditions caused by parasitic and anaerobic bacterial infections. It is available in various forms, including tablets, injections, creams, lotions, and gels. Metronidazole benzoate is used in veterinary medicine to treat off-label inflammatory conditions, such as 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 adviser 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 condition characterized by recurrent inflammation of the large intestine. Symptoms of colitis include acute diarrhea or loose stool 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)
• Gastrointestinal parasites (i.e., Giardia, Coccidia, and whipworms)
• Allergic colitis
• Primary IBD
• Contact with infected dogs

Depending on the type of colitis your dog has, it can last anywhere from a few days (acute colitis) to 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.

How much metronidazole can I give my dog for colitis?

Several factors influence how veterinarians administer metronidazole as a treatment for canine 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.

One factor that determines the amount of metronidazole given is your dog’s weight. Dr. Alleyne advises against pet owners calculating their own dosage. “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.”

Metronidazole side effects in dogs

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.

What if my dog misses a dose?

Life happens, and sometimes a dose gets missed. If you realize you’ve forgotten a dose and it’s within a few hours of the scheduled time, go ahead and give it. However, if it’s almost time for the next dose, skip the missed dose and just continue with the regular schedule. Never double up on doses to catch up, as this significantly increases the risk of side effects and toxicity. If you frequently miss doses or are unsure about what to do, don’t hesitate to call your veterinarian for guidance. They can help you adjust the schedule or offer advice to ensure your dog receives the full benefit of the treatment.

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 notes that the duration can vary depending on whether the dog receives recurring treatment or takes the drug in conjunction 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 experience persistent diarrhea, especially if blood is present in the stool. 

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, tylosin, 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.” In acute colitis, a temporary bland diet may be recommended while the gastrointestinal system is healing.

“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.”

When to see your vet

Knowing when to seek veterinary attention is paramount. While some mild digestive upsets can resolve on their own, colitis often requires medical intervention. Prompt action can prevent complications and reduce your dog’s discomfort.

Persistent or Worsening Symptoms

If your dog’s diarrhea, straining, or other colitis symptoms persist for more than 24-48 hours, or if they seem to be worsening despite home care or initial medication, it’s definitely time to see the vet. This suggests that the problem isn’t resolving on its own or that the current treatment is insufficient. Prolonged diarrhea can lead to dehydration and electrolyte imbalances, which can be serious, especially in puppies or senior dogs. Don’t wait until your dog is severely debilitated.

New or Severe Symptoms

Any new, severe, or alarming symptoms warrant an immediate call to your veterinarian. This includes:

• Extreme lethargy or weakness: If your dog is unusually tired, sluggish, or unable to get up.
• Significant abdominal pain: If your dog cries out when touched, hunches, or seems extremely uncomfortable.
• Profuse or watery diarrhea: Especially if it’s accompanied by vomiting and a refusal to drink water, as this increases the risk of rapid dehydration.
• Large amounts of fresh blood or dark, tarry stool (melena): While a few streaks of fresh blood with colitis can be common, large volumes or tarry stool suggest more serious internal bleeding.
• Uncontrolled vomiting: If your dog can’t keep down water, they are at high risk of dehydration.
• Any neurological signs: As discussed earlier with metronidazole side effects, but also potential signs of other serious conditions.

These symptoms could indicate a more severe underlying condition or a rapidly deteriorating situation that needs urgent medical attention.

Recurrent Episodes of Colitis

If your dog experiences repeated episodes of colitis, even if they seem to resolve with treatment, it’s a clear sign that an underlying issue needs to be identified. This is where the distinction between acute and chronic colitis becomes crucial. Recurrent episodes suggest that the root cause hasn’t been fully addressed. Your veterinarian will likely recommend further diagnostic tests, such as fecal analyses, blood work, imaging (X-rays or ultrasound), or even dietary trials and biopsies, to determine the cause of the problem and formulate a long-term management plan. Ignoring recurrent colitis can lead to chronic discomfort and potentially more serious health issues for your dog.

Frequently asked questions about canine colitis medication

Can metronidazole cure colitis in dogs?

Metronidazole can help manage symptoms of colitis caused by bacterial overgrowth or inflammation, but it may not cure the underlying condition, especially in chronic cases.

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

Most dogs show improvement within two to three days, though some may need a full course of treatment before symptoms resolve.

Is metronidazole safe for dogs?

Metronidazole is generally safe when used short-term and as directed, but it can cause serious side effects if overdosed or used for long periods.

What are the most common side effects of metronidazole in dogs?

Common side effects include vomiting, diarrhea, reduced appetite, tiredness, and drooling, while neurological symptoms are less common but more serious.

Can metronidazole cause neurological problems in dogs?

Yes, high doses or long-term use can lead to tremors, seizures, loss of coordination, or weakness, which require immediate veterinary attention.

How long can a dog safely take metronidazole?

Most dogs are treated with metronidazole for five to seven days, although the treatment length may vary depending on the response and whether the condition is acute or chronic.

What should I do if metronidazole doesn’t help my dog’s colitis?

If symptoms persist or worsen, your veterinarian may recommend further testing, dietary changes, supplements, or alternative medications.

Are there alternatives to metronidazole for treating colitis in dogs?

Yes, alternatives may include other antibiotics, steroids, probiotics, prebiotics, or prescription diets, depending on the cause of colitis.

Should metronidazole be given with food?

Many veterinarians recommend giving metronidazole with food to reduce stomach upset, but you should follow your vet’s specific instructions.