Can I Give My Dog Miralax for Constipation? + How Much is Safe

Can I Give My Dog Miralax

A constipated dog will be in pain and discomfort. Tell-tale signs will be lack of stools for two days, straining when crouching down, and painful yelps. It’s a hard thing to watch, so as an owner it’s tempting to reach for the first available treatment you can find. One of those treatments is said to be Miralax.

I decided to do some research into this, collating notes from pet and veterinary forums on the web to give you the most helpful guide to how much Miralax your dog should have, plus whether it’s even a good idea.

After all, it doesn’t sound that wise to give a dog a laxative medicine that’s intended for humans… but from what I have found online, it can be used for dogs and cats too.

Read on to find out whether you can give your dog Miralax, and just how safe is this powder to use on dogs according to what people have said online.

Can I give my dog Miralax?

There are multiple sources online which cite vets saying Miralax powder can be given to dogs to help with constipation. However, there are also other dog owners who say their dog has been ill as a result of having Miralax, so expert opinion should be sought before use.

The bottom line is that before you give your dog Miralax powder, please talk with your own vet first to get their professional opinion. All dogs are different and could react in different ways to medicinal products so don’t be hasty and get expert advice first – once you have that, you can buy Miralax on Amazon.

As I said though, there are countless examples online where dog owners and vets have said Miralax powder is fine to use on dogs, and the positive comments do outweigh the negative reports.

The general consensus is that aside from being an over the counter drug that relieves human constipation, Miralax can also be used on dogs to achieve the same purpose. It should not be viewed as long term fix and professional advice should be sought from a vert before you give it to your own dog.

How much Miralax for a dog?

Dosage should be very conservative and vary according to how much your dog weighs. There could be dire side effects if instructions are not followed carefully.

From what I have found online, typical dosage guidelines are as follows:

  • Small dogs: 1/8 to ¼ teaspoon every 12 hours (twice daily).
  • Medium sized dogs: ¼ to ½ teaspoon every 12 hours (twice daily).
  • Large dogs: ½ to ¾ teaspoon every 12 hours (twice daily).

The issue here is that we need to define what a small, medium, or large dog is which can confuse the dosage amounts for how much Miralax you give your dog.

I then found some alternative information online which is more specific on weight, saying you should give you dog 1 teaspoon a day for every 50 pounds they weigh, or a ⅕ for every 10 pounds. That sort of aligns with the information above and is said to be conservative.

If this information is correct, then it could mean the following dosage amounts:

  • Miralax for a 70-pound dog: 1 and ⅖ of a teaspoon every 24 hours.
  • Miralax for a 50-pound dog: 1 teaspoon every 24 hours.
  • Miralax for a 40-pound dog: ⅘ of a teaspoon every 24 hours.
  • Miralax for a 30-pound dog: ⅗ of a teaspoon every 24 hours.
  • Miralax for a 20-pound dog: ⅖ of a teaspoon every 24 hours.
  • Miralax for a 10-pound dog: ⅕ of a teaspoon every 24 hours.

Before you give Miralax to your dog, please check the dosage with your vet. It is a laxative intended for humans, and so the dosage amounts you see on the packaging will differ for canines.

Comments from vets online also say you should ensure your dog is properly hydrated whilst taking any form of laxative. This will help to soften the stools and ease the passage with less straining.

How to give your dog Miralax powder or liquid

From what I have read online, the best way to administer the Miralax to a dog is through their food. Vets and dog owners say you should put it into their food, mixing it in so the dog cannot see it.

What happens when you give a dog Miralax? 

Miralax loosens the dog’s stool by stimulating the nerves in the colon, thereby causing muscle contractions that propel the stool through the colon. It has an osmotic effect whereby it increases the water content in the stool thereby making it easier to pass through the digestive system and out the other end.

Vets say that Miralax will ease a dog’s constipation within 24 to 48 hours of administration. If it does not work, then it could be a sign of a more serious problem and therefore the dog owner should consult a vet immediately. 

It is not recommended that Miralax is taken with any other drugs as this could mean the absorption of Miralax into the dog’s body is prevented. If a dog is on other drugs and still constipated, it is recommended that Miralax is issued within two hours before or after the other drugs have been taken so as to maintain its effectiveness. 

Should you give your dog Miralax? 

Unless you have been advised to by your vet, do not give your dog Miralax or any other medicinal that was manufactured for human consumption. Whilst there are multiple references online to people giving this laxative to their dog, there are also some comments which raise concerns to me. 

For example, here are two comments found on a web forum:

“Give your dog or cat anything but Miralax! It is very dehydrating and backs them up more. It actually caused my little Lola to go into seizures.”

“I would avoid the use of Miralax. My vet recommended that I give it to my dog when he was unable to poop for a couple of days. After just one dose he had a severe acute pancreatitis attack.”

Whilst these are more the exception than the rule, it’s enough of a red flag to make me say only give Miralax to your dog with the go-ahead from a vet.

Possible side effects of giving a dog Miralax

My research has uncovered some possible side effects including:

  1. Vomiting: Miralax contains an ingredient called polyethylene glycol which some dogs may have a negative reaction to and vomit.
  2. Diarrhea: This is usually because the dog does not augur well with the polyethylene glycol component of the drug or because the dosage exceeds the recommended amount according to the dog’s weight.
  3. Pancreatitis: Some people have reported that large amounts of Miralax could lead to an overworked pancreas and therefore lead to pancreatic breakdown.

Alternatives to Miralax

As well as other medicines your vet might prescribe, I have heard of more natural methods, one being pumpkin and wheat bran. Here’s a list of some alternatives including some from vets.

  1. Keep your dog hydrated: When dogs drink water it will help to soften the stool and ease passage out of the body.
  2. Give your dog a high fiber diet: Increase their fiber intake helps to digest food faster and ease bowel movement.
  3. Add oil to your dog’s diet: Vegetable and olive oils also help to soften stools.
  4. Feed your dog pumpkin: This is the number one natural remedy for canine constipation as its rich in fiber and has high water content. Feed in a pureed form as it easier to eat and does not require any chewing. I wrote a guide previously which explains how pumpkin works for dog constipation.
  5. Injections by a vet: Drugs can be injected and are much more effective as they absorb quickly into the dog’s bloodstream to start working immediately.
  6. More exercise: Regular exercise can help to boost a dog’s metabolism and get the digestive system working better.


As effective and efficient as Miralax can be for easing constipation in dogs, not all dog owners report positive results. After all, is intended for humans, but is used by some pet owners to help their dog’s constipation – often on advice from a vet.

I am not recommending that you give it to your dog without first having spoken with a vet.

The information on this page has been collated from other online resources, and should not be viewed as medical or veterinary advice.

Marc Aaron

I write about the things we've learned about owning dogs, the adventures we have, and any advice and tips we've picked up along the way.

Recent Posts