Can You Use MiraLAX for Dogs?

Yes, MiraLAX is a readily available laxative for constipated dogs.


MiraLAX is an over-the-counter laxative. It is an unflavored powder, which makes it perfect for mixing into your dog’s food or a little bit of water. MiraLAX works by pulling water into your dog’s GI tract, making the stool softer and easier to pass.

The active ingredient in MiraLAX is polyethylene glycol 3350. Many generic versions include the “LAX” in their names but read the ingredients label to ensure you’re getting the right medication.

While MiraLAX is generally safe, it’s wise to only give this medication under the guidance of your dog’s veterinarian. Giving too much could result in diarrhea or even dehydration. And you need to be certain the dog simply constipated and not battling something more serious.

When to Use MiraLAX for Dogs

MiraLAX is generally used to resolve and prevent constipation.

Symptoms of constipation in dogs include:

  • Straining to defecate
  • Small, hard stools
  • Infrequent defecation
  • Blood on stool
  • Discomfort when pooping
  • Distended abdomen
  • Poor appetite
  • Vomiting

While dogs can have a single bout of constipation that doesn’t recur, constipation also can be caused by a variety of medical problems, some of which are serious. Many signs of constipation are also symptoms of different health problems.

Constipation at the Vet’s Office

Your veterinarian will do an exam and possibly an X-ray to verify that your dog truly is constipated. He or she may recommend additional testing such as bloodwork, a fecal exam, or an abdominal ultrasound to determine why your dog is constipated. This is especially important if your dog suffers from frequent constipation.

In severe cases, your dog may need an enema or deobstipation under anesthesia to manually remove large amounts of hard, stuck stool from the colon.

If this is your dog’s first time being constipated and your veterinarian doesn’t find anything alarming, he or she may recommend MiraLAX for just a few days to get your dog’s bowels moving properly again.

Dogs who have chronic bouts of constipation or are on medications that can cause constipation may stay on MiraLAX long-term.

Dog Laxative Dosing

Your veterinarian will recommend a specific dose of MiraLAX for your dog based on her size, stool quality, and overall health.

In general, small dogs start at 1/8 or ¼ teaspoon of powder twice a day, while large dogs might get ½ to ¾ teaspoon twice a day. Depending on how your dog responds, your veterinarian may have you increase or decrease the dose.

You will work toward the dose that makes your dog’s poop soft but still formed. Liquid stool means the dose is too high, while hard stool means the dose is too low.

MiraLAX Caution With Dogs

This is worth repeating: Do not give MiraLAX to your dog without consulting your veterinarian. Giving a laxative when it is not needed could complicate some health situations, such as an intestinal blockage from eating a toy or giving too much could cause dehydration.

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Kate Basedow, LVT is a long-time dog enthusiast. She grew up training and showing dogs, and is active in a variety of dog sports. She earned her Bachelors Degree in English from Cornell University in 2013, and became a licensed veterinary technician in New York in 2017. She has been writing professionally about dogs for most of her life, and has earned multiple awards from the Dog Writers' Association of America. Kate currently has three dogs at home, as well as a cat, two zebra finches, and six ducks.