Metronidazole Dog Not Pooping

Photo by doctor-4-u on Flickr

Have you recently taken your dog to the vet and they have been prescribed with Metronidazole?

Are you now concerned because after a few days of treatment your dog isn’t pooping?

Well, in this article I outline possible reasons for this as I explain exactly what Metronidazole is and what some of the possible side effects are?

So, without further ago let’s get stuck in.

And in my first section I provide a bit of a Metronidzole 101 and this medication has a bit of a surprise in store for dog owners such as you and I.

Keep reading to find out exactly what it is…

Metronidazole- some basics

Metronidazole is an antobiotic that has been designed, tested and used specifically for people not dogs.

In humans, it is used to treat skin infections and mouth infections.

Although it is hasn’t been approved by the Federal Drugs Administration (FDA) it is used commonly by vets to treat dogs, cats and horses.

And don’t be panicked by this fact- many drugs which were designed for humans are used to help our dogs as well.

And, in dogs, it is most commonly used to treat diarrhea and other intestinal infections.

Can Metronidazole cause constipation in dogs?

While there are quite a few possible side effects, constipation is not listed.

This is according to more than one website.

If you are interested in this article because of a constipation problem with your pooch, there are some remedies further along in this article.

The American Kennel Association is one of them. Naturally, an overdose could cause this problem.

However, it is unlikely.

The probable reason for confusion on this issue is because some of the infections it is used for cause diarrhea.

It is easy to suppose that it will then cause constipation.

If the dog becomes constipated, it is best to check with the vet, as this is not a known, listed side effect.

Can metronidazole cause neural problems?

According to many sources, including several studies in PubMed, the drug does have a rare side effect of neural problems.

At this point, it’s known that twenty six dogs had mild to moderate neural problems when taking the drug.

How long do the neural complications last?

The median time from for the symptoms to go away was three days.

Some dogs may get over it sooner and some dogs may take more time to get over it.

Only one dog had any lasting effects according to the MRI.

That dog has some lesions on the brain.

If neural problems happen, should I stop giving me dog metronidazole?

Always check with your vet before stopping any prescribed medication.

It is usual that the drug will be stopped, however if the dog is seriously ill, another medication may need to be prescribed.

What natural remedies are there for constipation in dogs?

Constipation is one of the most common problems dogs can face.

It can be caused by a lot of things, so having some natural remedies on hand can be beneficial to both you and your dog.

  • Walking: If your dog doesn’t get enough exercise, constipation is likely to be a frequent problem. If you already walk your dog, try adding a bit more to the walk. If your dog doesn’t get enough exercise, see if you can encourage him or her to exercise more. This gets the digestive system moving.
  • Olive oil: Besides being healthy for your pet, it can help lubricate the digestive system. That will help get some of the harder matter from lower down in the colon to come out. It may also be less painful. It can be mixed in with the dog’s food.
  • Pumpkin: Canned or steamed pumpkin can help many digestive issues in your pet. If your dog is taking metronidazole, it may help with the issues that cause him or her to need the medication. Besides the other health benefits, pumpkin contains a great deal of fiber. Bulk fiber is often needed to improve motility in the gut.
  • Fiber: Adding unsweetened wheat bran or other fibers to your dog’s food can help both resolve and prevent constipation. With some types of fiber, such as psyllium, it is extremely important to make sure there is enough fluid intake. Otherwise it can cause serious problems in the stomach.
  • Probiotics: Like humans, dogs need to have a healthy gut biome. Probiotics can give that. You may want to ask your vet about prebiotics. Probiotics can be store bought, but making it at home isn’t that hard. There are a lot of recipes online. 
  • Apple cider vinegar: Speaking of prebiotics, apple cider vinegar is one of them. A small amount, say a teaspoon or so, in the dog’s water dish can help. Make sure to keep it to small amounts because larger amounts can irritate the poor pet’s stomach. 

What are some of the other side effects does using metronidazole have?

Like most drugs, there are some side effects that are possible.

Most of them are relatively minor, although a few may require you to consult your vet.

These side effects include diarrhea, nausea and vomiting, drooling, loss of appetite, gagging, fatigue/lethargy, fever and blood in the urine.

If the side effects are severe, call the vet. 

Along with the neural problems mentioned above, there are other rare side effects from taking metronidazole.

These include insomnia, liver damage, low platelet count, irregular/slow heart beat, dilated pupils, seizures, tremors and stiffness.

The neural problems can be just as frightening.

Staggering, abnormal eye movements, loss of balance, head tilt and stumbling/knuckling.

There is also an addition to the list that is a little scary.

It just says strange behavior, which could mean just about anything.

What are the main causes of constipation in dogs?

While dogs face some of the same causes of constipation as their human counterparts, dogs do have a few extra things to worry about. One of the most common is actually related to their fur.

Dogs with long fur or those that groom themselves excessively are prone to constipation. It’s sort of like a hair ball in cats, only they rarely regurgitate the excess. Like hair, any other substance that is irritating or downright indigestible can also cause constipation.

Suddenly changing a dog’s diet can also lead to constipation. This is why most vets recommend that changes are made gradually; adding small amounts at first and increasing over a period of one to two weeks.

Fear and anxiety are another cause. Events like the Fourth of July or New Year’s Eve, when a lot of people let off fireworks (and other loud noises) can cause a dog to develop constipation. That is one reason why many people will use thunder shirts for their pets.

Arthritis or injuries to the hind quarters, especially the pelvis, can cause the dog to put off passing stool. This, in turn, leads to constipation. If the dog has these problems, check with the vet to determine what can be done to mitigate the pain.

Like humans, various illnesses and conditions can cause the problem. Hormone changes, problems with the bowels and some medications can create this situation. Obstructions in the bowel are a threat as well. The problem here is that the dog may ingest something that can’t pass through. That is an emergency situation.

How likely is it for dogs to go quickly between having constipation and diarrhea?

It is not likely unless there is a problem. This sort of thing can indicate serious internal problems such as liver or kidney disease or problems with the gut itself.

Metronidazole for dogs can be a very useful tool in handling such serious problems as giardia and other infections. It is a strong drug, but if your vet has prescribed it, your dog needs a strong medication. If you notice side effects, keep a diary of them.

If the side effects appear serious to you, call your vet. The vet would rather you call for something that isn’t a serious problem much more than if you don’t call at all because you don’t want to be a problem. If nothing else, the vet can reassure you that the situation is normal.

If your pet becomes constipated while taking this medication, that also needs to be reported to your vet. As this is a common question, veterinarians and research scientists need to know how common it is. Just because they don’t list it doesn’t mean it may not be a problem. It simply may have never been reported, or thought to be something like a slight overdose.

There may be times when the vet will want to report the side effects. This is particularly true if they are of the neurological variety. Reporting the symptoms, how long it takes for them to disappear and what the dog’s condition is afterwards is a great help in making sure the medication is improved.

Never stop a medication without confirmation from a vet. If it is after hours, there is likely to be an emergency vet around that can advise you. This may be an expensive call, but it is well worth it to protect you and your dog.

Natural remedies such as those listed in this article are for your information only. The USFDA has not approved of these remedies and gets testy with those who don’t mention it. That doesn’t mean they don’t help, just that they haven’t been proven to the government’s standards.

Always check with your vet when you want to make changes and/or additions to your dog’s diet. The vet will know your dog’s conditions and any medications your pet may be on. That can alter what your pet can and can’t have. As mentioned, make changes slowly.

James Grayston

My name is James and I love dogs. have owned four Golden Retrievers in the past 15 years. Currently I own two "Goldies"- a five year old and a seven month old. The photo shows me with our youngest when she was about 7 weeks old!