My Dog Still Has Diarrhea After Metronidazole

My Dog Still Has Diarrhea After Metronidazole

Last Updated: August 18, 2023
correct answerThe Short Answer is:

In case your dog continues to suffer from diarrhea after completing a course of metronidazole, contact your veterinarian. Medications or treatment types may need to be changed or extended for your dog.

In this article you will know the answer to the query “My Dog Still Has Diarrhea After Metronidazole“.

The condition of diarrhea in your dog is a distressing experience for both the animal which is kept awake at night by frequent bathroom trips as well as you who have to be on call for those bathroom trips and clean up after an accident. 

My Dog Still Has Diarrhea After Metronidazole

The vet told you that metronidazole will cure the problem at least thats what he said. 

Unfortunately many pet parents find that their dog is as miserable as ever after taking antibiotics. 

What can be done?

We need to first examine this drug in more detail and see whether it is indeed effective in treating all types of diarrhea. 

Its an antibiotic after all and these types of drugs often cause diarrhea. The following article will discuss what metronidazole is its side effects as well as other diarrhea remedies that you may want to try for your pet. 

What is Metronidazole?

In humans and pets alike metronidazole has been around since the 1950s and is widely used to treat a wide range of infections. 

The most important use of metronidazole is to treat anaerobic bacteria meaning bacteria which do not require oxygen for survival. 

On the other hand metronidazole has been used as an antiprotozoal killing parasites such as Giardia. 

Upon receiving metronidazole from the vet you’ll probably be pleasantly surprised at how fast your pet gets better. 

Within 24 hours many pet parents reported their dogs stools were solid well-formed and normal. 

As soon as you stop giving the drug to the dog the dogs watery stools begin again.

The reason for this may be that veterinarians tend to overprescribe this type of medicine treating diarrhea of all types not just those caused by the bacteria metronidazole targets. 

So metronidazole only alleviates the symptoms without treating the underlying cause of the dogs problem which is why diarrhea returns once the antibiotic is stopped.

What is Metronidazole Used For?

The fact that you’re reading this article indicates that your pet is suffering from diarrhea. 

Clostridium difficile is the most common cause of diarrhea in humans and animals.

The antibiotic metronidazole is extremely effective against bacteria in the Clostridioides family. By going into the bacteria and killing it instead of slowing its growth it works. 

The antibiotic is also used for treating gastritis caused by Helicobacter bacteria. Gallbladder and bile duct infections are treated with this medicine. 

Infections of the tooth and jaw can also be treated with metronidazole since it can penetrate bone structures.

How Long Does Metronidazole Take to Work in Dogs?

It can take as little as one to two hours to see some improvement according to experts. 

It is not that the dog would be perfectly fine in such a short period of time but the frequency of those dreadfully annoying bathroom trips could be reduced. 

It is expected that the consistency of the dogs stools will improve gradually. As a result it will take at least a couple of days before the dog feels better. 

To treat diarrhea veterinarians usually prescribe a five to ten day course of antibiotics. The veterinarian may prescribe 14 days of metronidazole if the situation is really severe.

How is Metronidazole Administered to Dogs?

Various forms of metronidazole are available including pills and liquid suspensions. 

Usually doctors recommend a dosage of 5-7 mg per pound every 12 hours for diarrhea. 

In cases of giardia the dosage might be increased to 7-11 mg per pound of body weight but only once a day. 

The following are just general recommendations. 

It is important to always follow the doctors orders since they consider other factors such as the dogs age and general health condition.

You’ll usually need to give the dog metronidazole in pill form and this can be challenging since the medicine is extremely bitter. 

Donot crush the pills since this will make it more difficult for the dog to accept his medicine. 

Your dog is likely to be unable to resist a treat in which the pill is hidden.

My Dog Still Has Diarrhea After Metronidazole?

The antibiotic metronidazole is very effective against various types of bacteria which may be causing your pets continuing health problems. 

In addition to killing the bad bacteria the antibiotic is too effective. Metronidazole wipes out good bacteria in the dogs gut such as Fusobacteria which contributes to digestion when it fights bacteria like C. Difficile. 

In one study a 14-day course of metronidazole greatly reduced the types of bacteria in a dogs microbiome or the total number of microorganisms living inside his intestines. 

A study found that certain bacteria had been virtually eliminated by the antibiotic while those that remained were very small in number.

The microbiome of the dog will need time to get back to normal. 

Study results revealed that the dogs microbiome was horribly unbalanced even after four weeks. 

You cannot expect his digestion to be back to normal at this point.

During the duration of the metronidazole treatment dogs can be given probiotics to help mitigate the devastating effects on the animals microbiome. 

This is why people take probiotics when they are on antibiotics and it can also help dogs preserve the good bacteria in their guts. 

Is Metronidazole Effective Against Giardia? 

In addition to being an antiprotozoal metronidazole has been used for decades to treat dogs infested with the parasite giardia. 

In most cases contaminated water transmits the microscopic parasite Giardia duodenalis to dogs. 

As soon as this unicellular parasite latches onto the intestinal walls it causes an acute episode of foul-smelling blood-tinged diarrhea. 

This tiny parasite has developed resistance to metronidazole according to recent studies. 

The antibiotic alone might not be enough to eradicate the parasite completely if your vet recommends it. 

Because of this the parasite will still remain after a week of metronidazole and at the same time the dogs intestinal biome has been destroyed. 

After taking his meds off the dog is still suffering from watery stools and is feeling miserable. 

In the present day experts recommend combining metronidazole and fenbendazole for the treatment of giardia. 

What are the Side Effects of Metronidazole?

Metronidazole can cause a number of unpleasant side effects as with any medicine. Among these are:

  • Muscle control loss
  • Coordination problems
  • Tremors
  • Seizures
  • Vomiting

In addition experts recommend not giving metronidazole to a pregnant or nursing dog. 

When puppies move to their new homes they often experience episodes of diarrhea and it is assumed that they are infected with a parasite. 

Sadly worried pet parents rush to the vet and almost always get prescribed metronidazole. 

In many cases this is a recipe for disaster because the puppy will have a hard time restoring the balance of the intestinal microbiome and will need more antibiotics. 

A veterinarian also recommends caution when a dog is known to have liver problems as the drug may worsen these conditions. 

What are the Alternatives to Metronidazole?

Dogs may also be at risk for overuse of antibiotics as doctors caution against it constantly. 

There is a simple solution to the problem. 

Your vet will prescribe metronidazole if your dog has diarrhea since experience shows that it stops diarrhea and what happens next week is less important.

In order to be sure that the diarrhea is indeed caused by bacteria it would be ideal for the vet to run a full set of tests on your dog. 

A fecal matter test should be included. Running all these tests takes time and costs more money than pet owners can often afford so its easier to prescribe a drug and see what happens. 

Furthermore giardia is notoriously difficult to diagnose so a doctor might just assume it is present.

Even if your dog is not in a very bad condition you should consider changing his diet and see if that helps. 

In fact diarrhea is usually caused by an unknown cause and can be treated by putting him on bland food for a few days. 

The bland diet consists of boiled rice and unsalted chicken breast. 

It is better to give the dog small meals at regular intervals rather than one large meal. You can wait until the dog becomes truly hungry so he will change his mind if he is not happy. 

Pureed pumpkin can also be added which calms bowel inflammation and adds bulk to stools. 

Because diarrhea is often associated with an unbalanced microbiome you should also address that issue. 

As a prebiotic you can use fibers such as inulin and psyllium (brand name Metamucil) which help balance the intestinal flora and improve the quality of the dogs stools.

S boulardii is another dietary supplement you can try. It supports the growth of beneficial bacteria.


In dogs metronidazole is one of the most common remedies for diarrhea. 

If however Clostridium difficile is not the root cause of the problem the antibiotic might make things worse rather than solve it. 

If the dog is suffering from diarrhea of unknown origin it is best to use a more conservative approach such as a bland diet and prebiotics to correct any imbalances in his intestinal microbiome. 

When the vet determines that metronidazole is actually necessary ensure the dog also gets probiotics to help preserve the good bacteria so he would not experience diarrhea again after he finishes the antibiotic course.

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Amanda Dogs Trainer

Amanda (Author)

With over a decade of experience, Amanda is a distinguished dog trainer. Her expertise in canine behavior has transformed countless lives, fostering harmonious human-canine connections. Through compassionate and personalized approaches, she empowers owners to understand and connect with their furry companions, creating a legacy of joyful tails and transformed lives.

Osvaldo Maciel Dogs Trainer

Osvaldo Maciel (Content Reviewer)

Osvaldo Maciel, a stalwart in the field with 14 years of experience, is a revered dog trainer. His journey is defined by a profound understanding of canine behavior, shaping unbreakable human-canine bonds. Osvaldo guides owners to connect with their beloved pets, leaving an indelible mark of happiness and transformation. His legacy shines through the countless lives he has touched.

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