Can Dogs Take Miralax for Constipation? (Read This First!)

Can Dogs Take Miralax for Constipation

Depending on your dog’s size, weight, and how severe the constipation is, your vet will determine the right Miralax dose. Typically, the dose ranges from 1/8 teaspoon for small dogs to 3/4 teaspoon for large dogs.

In the dog community, there have been raging discussions regarding the healthiness of Miralax for constipated dogs. Questions on this cut across how specifically Miralax works, how long before the dog starts experiencing the laxative effect, and how best you can administer Miralax to your dog. Also, are there other healthy alternative home treatments for a constipated dog? Read on to find authoritative answers on these.

How Does Miralax Work for Dogs?

Miralax (with the generic name of polyethylene glycol 3350) is an osmotive laxative known to initiate bowel movement, amplifying the water content of your dog’s stool so that it is far less discomforting to pass off.

Miralax works by colon nerve stimulation in your dog. Consequently, the muscle contracts, pushing the feces through the dog’s colon. As an osmotive laxative, Miralax makes it much easier for your dog’s stool to be transported through its digestive system by making it less dry and compact. Miralax works best when used in relieving occasional constipation.

How Long Does It Take for Miralax to Work on a Dog?

Typically, your dog should start experiencing improved bowel movement 24-72 hours after administering Miralax. If, after this period, you still notice the severity of constipation, it could be suggestive of a serious underlying health condition.

For best effect, Miralax shouldn’t be administered along with other drugs as such drugs could prevent the dog’s system from optimally absorbing the Miralax.

Preferably, you shouldn’t give your dog any drug 120 minutes before administering Miralax and 120 minutes after. This way, Miralax is more effective in your dog.

Is It Safe to Give a Dog Miralax? (Side Effects)

If used as a short term relief, Miralax wouldn’t wreak much havoc on your dog. Of course, there are side effects associated with Miralax for dogs.

Your dog could experience vomiting and diarrhea after ingesting Miralax. This is typical when your dog is reacting adversely to a chief component of Miralax, polyethylene glycol.

Such reactions are not uncommon when the Miralax dosage administered on your dog beats the recommended dosage for your dog’s weight range.

There are other cases where your dog can suffer pancreatitis. This is when the dog’s pancreas becomes overexerted, eventually breaking down. This is rare and only possible when your dog ingests excessive amounts of the drug.

However, so long you play safe and keep to the rules, such severe adverse effects should be very minimal. Below are some of the precautions you should observe when administering Miralax on constipated dogs:

  • Don’t use Miralax on dogs with hypersensitivity or dogs with an allergy to Polyethylene glycol
  • Miralax is a temporary fix and shouldn’t be used sustainably. Sustained administration of Miralax can trigger imbalances in your dog’s electrolyte formulation, causing dehydration, suppressed sodium, or excess potassium
  • Don’t administer Miralax on dogs with existing conditions like rectal bleeding, toxic colitis, or gastrointestinal obstructions. Pregnant or lactating dogs should also steer clear of Miralax.

Overall, it is important to get your vet’s approval before you administer Miralax on your dog, regardless of the urgency of the situation or severity of your dog’s constipation.

Your vet approval is even more critical if your dog is already on existing medication, so the Miralax doesn’t interact negatively with other dogs.

Upon giving your constipated dog Miralax, if you notice developments like difficulty in breathing, swelling, or even allergic reactions, get your dog to a vet immediately. An emergency visitation to the vet is also needed when your dog takes an excess dosage of the drug.

How Much Miralax for 80 lbs Dog?

For an 80lb dog, you should give it 1 and 2/5 of a teaspoon of Miralax every 24 hours.

How Much Miralax for a 50 lbs Dog?

A 50lb dog should not get more than one teaspoon of Miralax every 24 hours.

How Much Miralax for a 40 lbs Dog?

The optimal Miralax dosage for a 40lb dog is 4/5 of a teaspoon every 24 hours.

How Much Miralax for 20 lbs Dog?

A 20 lb dog shouldn’t take more than 2/5 teaspoon within 24 hours.

How Much Miralax for 5 lbs Dog?

A 5lb dog should have 1/5 teaspoon of Miralax every 24 hours.

Can You Add Miralax to Dog Food?

Miralax is maximally effective when delivered via the dog’s food. Of course, there is the psychological effect of administering Miralax via your dog’s food.

Although Miralax does not have a strong flavor, a keen dog would be less enthusiastic about eating the food if it sees you adding the drug to the food. The consequent loss of appetite could even extend that day. So ensure to mix the Miralax with the dog’s food out of sight.

Can You Put Miralax in the Dog’s Water?

Yes, there is no problem putting Miralax in the dog’s water. However, dog owners have reported higher drug efficiency when Miralax is administered via the dog’s food.

Home Treatment for Dog Constipation

Aside from Miralax, there are other viable alternatives to treating constipation in your dog. But before we jump into these remedies, it is important to authoritatively ascertain that your dog is suffering from constipation itself.

What signs should you watch out for your dog? Well, your dog is most likely suffering from constipation when you notice it has not defecated in days (say more than two).

If your dog’s stool is significantly dry and hard, even feeling like solid stones when you feel them, then constipation is at hand. You can also tell if your dog is experiencing constipation from the discomfort it experiences when defecating.

If it is straining to pass out stool with notably reduced liquid content in the stool (and in some cases, the feces being mixed with blood), then it is likely suffering constipation.

Now that you know, what is next? You can try any of the following home remedies. Take note that your dog could respond to each of these remedies differently (in terms of varying effectiveness). This is because there is no definitive therapy that works in all dogs in the world.

Check the Dog’s Bottom for Mats

In some milder cases, the said inability to defecate could result from the obstruction of the anus by thick mats of fur. This is prevalent in dogs with long hair. Such hair can get plated with feces, closing off the dog’s anal orifice. 

What can you do? Get some electric clippers to chop off such mats of fur. In the cases where you can’t take them off, you should reach out to a professional groomer or your vet. 

Resist the temptation to use scissors quickly. Aside from the risk of contamination, you could even hurt your dog.

Give Your Dog More Water

If your dog’s stool is coming out notably dry and even in the form of pebbles, it is highly likely that your dog is dehydrated. In such cases, the dog’s body tries to retain as much water from the stool, ultimately drying it up.

Make sure that freshwater is perpetually within your dog’s easy reach. Such ready accessibility to water is even more important when you have older dogs (with consequent mobility handicaps) or generally other dogs with arthritis.

Given the pains in moving, such dogs would prefer to save themselves the labor of moving to access the water, ending up dehydrated and consequently constipated.

Should you be feeding your dog canned food, you can dilute such foods with a bit more water so long it doesn’t distort its taste. This way, your dog is taking in more water.

Feed Your Dog Fiber-rich Foods

Typically, fiber should relieve your dog of constipation. But this is not always the case. In some dogs, fiber can worsen the severity of constipation.

Given this, it is best to test your dog’s response to this fiber therapy by feeding it small amounts of such fiber-rich foods and watching the effect.

Canned pumpkin is a rich source of fiber for your dog. The amount to feed your dog depends on its size. Bigger dogs can get up to a tablespoon of canned pumpkin mixed into their foods, while small dogs would make do with a teaspoon.

We will emphasize here that you shouldn’t administer pumpkin pie filling. Instead, it would be best if you went with plain canned pumpkin.

Exercise Your Dog

Giving your dog some form of controlled exercise enhances movement within its gastrointestinal tract. This is achievable by walking the constipated dog in the afternoon or morning. Before the walk, ensure your dog has an appreciable water intake.

In some cases, exercises around areas where other dogs have defecated come with a smell that can stimulate a bowel movement in your dog.

Resorting to liquid mineral oil for your dog’s constipation is highly prohibited. There is a substantial risk of severe pneumonia if your dog inhales such a substance.

Similarly, you shouldn’t administer an enema procedure (injecting liquid through your dog’s anus to stimulate the discharge of waste matter) unless your vet explicitly recommends it (and you know how to).

Seeing Your Vet About Chronic Constipation

Chronic constipation can cause a dangerous condition called obstipation. This is when critical constipation causes a blockage of your dog’s intestines.

Subsequently, this may deteriorate further into megacolon, a situation where the dog’s colon is abnormally enlarged, making it impossible for the passage of waste.

All these should necessitate the urgent visitation of your vet. When going to see your vet about such chronic constipation, ensure you are supplied with data about the last normal bowel movement your dog had.

You would also need to tell the vet about the dog’s stool color and how regular its defecating routine was. The vet may request to know what your dog has been eating (including the non-food items) and how frequently.

What Causes Constipation in Dogs?

Constipation is more common in dogs than many owners may realize. Knowing what causes constipation can help you determine when your dog needs help to ease the condition.

Diet and Lifestyle

Issues like dehydration, poor nutrition, and lack of exercise slow down the digestive tract leading to constipation. Some specifics include:

  • Dehydration – Not getting enough water leads to dry, hard stools that are painful to pass.
  • Low-Fiber Food – Low-quality filler-laden kibbles with little fiber are hard to digest.
  • Sudden Diet Changes – Abruptly switching foods disrupts their digestive balance.
  • Sedentary Lifestyle – Dogs that are inactive frequently have sluggish bowels.
  • Scavenging & Eating Foreign Items – Ingesting non-food items can obstruct their system.


Certain prescription and over-the-counter medications list constipation as a potential side effect. These include:

  • Antihistamines for allergies
  • Antacids for upset stomach
  • Diuretics for blood pressure
  • Pain relievers
  • Chemotherapy drugs
  • Anesthesia from surgery

Existing Health Conditions

Several illnesses involve constipation as an associative symptom:

  • Neurological disorders – nerve damage impairs normal function
  • Spinal injuries further along the back
  • Blocked anal glands prevent releasing stool
  • Inflammation along the colon region
  • Pelvic area trauma
  • Digestive diseases – inflammatory bowel disease, etc.
  • Tumor or cancerous masses obstructing the bowels

Secondary Symptom

Constipation can develop secondary to other illnesses, like:

  • Dehydration from repeated bouts of vomiting or diarrhea
  • Side effect from antibiotic disruption of gut flora balance
  • Indirect reaction to treatments for another condition

Age-Related Changes

For both puppies and senior dogs, normal changes increase susceptibility:


  • Still developing bowel control leading to retention
  • Transitioning to solid foods from mother’s milk
  • Worms are common in this age bracket


  • Weakening muscle walls make defecating harder
  • Side effects as treatments accumulate
  • Reduced immune function means more GI infections

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