Dog Constipation: Causes, When to Worry and What to Do

How Long Can a Dog Go Without Pooping?

Most dogs poop at least once a day, often around mealtimes.³ Missing a day isn't usually a concern in a dog that is eating, drinking and acting normally. VCA Animal Hospitals advises calling your vet if your dog hasn't had a bowel movement within 48 to 72 hours of the previous one, and the American Kennel Club suggests contacting a vet after 24 hours to be safe, and sooner if your dog is straining.^3,4 Don't wait that long if your dog is straining, in pain or vomiting: see a vet the same day.^4,1

The longer stool stays in the colon, the drier and harder it becomes, which makes it even harder to pass.² Severe, long-lasting constipation in which the dog can't pass the hard mass at all is called obstipation.^1,3

Why Is My Dog Constipated?

The most common cause is eating something that can't be digested properly, such as bones, plant material or hair, especially when the dog isn't drinking enough.^3,2 Other causes include:^3,1,2

• Not drinking enough water, or any illness that causes dehydration
• A sudden change of diet and too little exercise
• Swallowed objects such as bones, toys, fabric or garbage, which can also cause a bowel obstruction
• Medications, including some antihistamines, diuretics, opioid pain relievers and sucralfate
• Pain when squatting, for example from arthritis, pelvic injuries or anal gland problems^3,9
• Pressure on the colon from an enlarged prostate (in unneutered males), a narrowed pelvis after a fracture, or a tumor
• A perineal hernia, a weakness in the muscles beside the anus, mostly in older unneutered male dogs^7,8
• Nerve and hormone problems, such as spinal disease and hypothyroidism
• Stress, fear or anxiety, which can make a dog hold its stool

Constipation or Blockage? Three Look-Alikes to Rule Out

Straining can mean several different things, and some of them are emergencies.

• Intestinal blockage: a swallowed object usually causes vomiting, loss of appetite, lethargy and belly pain, and sometimes diarrhea. Without treatment, shock from fluid loss can kill a dog quickly. Young, large-breed dogs are most at risk.^1,5 Read more about bowel obstruction in dogs.
• A blocked bladder: a dog that squats and strains but produces no urine, or only a few drops, may have a urinary blockage, for example from bladder stones. It's more common in males and needs emergency care.⁶ Watch closely to see whether your dog is trying to pee or poop.
• Colitis: inflammation of the large intestine causes frequent straining with small amounts of soft or liquid stool, often with mucus or a little bright red blood.¹⁰ To confuse things further, a constipated dog can leak liquid stool around a hard mass, which looks like diarrhea.³ See our page on colitis in dogs.

For a full list of signs, see dog constipation symptoms.

What You Can Do at Home

For a mildly constipated adult dog that is otherwise bright and eating, simple steps often help:^2,1,3,4

• Make sure your dog drinks enough water. Adding canned food to meals also adds moisture.
• Go for a gentle walk, which encourages a bowel movement.
• Add fiber to the diet, with your vet's advice on what kind and how much.
• Remove bones and anything else your dog shouldn't be chewing.

Don't give human laxatives or enemas unless your vet tells you to. Human laxatives can be very dangerous for dogs, and over-the-counter phosphate enemas can cause serious poisoning, especially in small dogs.^1,11 See our guide to home remedies for dog constipation for pumpkin, fiber and what to avoid.

How Vets Diagnose and Treat Constipation

Your vet will feel your dog's belly and do a rectal exam, and will often take X-rays, which show how much stool is retained and can reveal bones or other objects.^1,3 Bloodwork, a urinalysis and sometimes ultrasound help find an underlying cause, especially if the problem keeps coming back.^3,2

Treatment depends on how severe it is:^2,3,1

• Mild cases: water, a high-fiber or other therapeutic diet, and sometimes a short course of a stool softener or laxative chosen by your vet, such as lactulose, docusate or polyethylene glycol 3350
• Dehydrated dogs: fluids first, because laxatives shouldn't be given to dehydrated animals
• Severe cases: enemas given at the clinic, or manual removal of the stool under general anesthesia, which can take 2 or 3 sessions over several days
• Underlying problems such as a perineal hernia, an enlarged prostate or a swallowed object may need surgery or other treatment, such as neutering^8,5,7

Medicines that speed up the colon, such as cisapride, are only used once a blockage has been ruled out.^3,12

Chronic Constipation and Megacolon

Most constipation is easily corrected, and most dogs recover quickly once the cause is treated.^2,3 If constipation keeps coming back or isn't treated, the colon can stretch and lose its ability to move stool along, a condition called megacolon. It's uncommon in dogs, but serious.^3,2 Severe cases may need surgery to remove part of the colon, so recurring constipation is worth investigating early.³

Preventing Constipation

• Keep fresh water available at all times.^3,2
• Don't give bones, and keep garbage, toys and fabric that your dog might swallow out of reach. Cooked bones can splinter and injure the gut.^13,14
• Make diet changes gradually, and make sure your dog gets regular exercise.^3,4
• Keep long-haired dogs well groomed, since swallowed hair can contribute to constipation.³
• Ask your vet about pain relief for older dogs with arthritis, since pain can make squatting difficult.³

More on Dog Constipation

• Dog constipation symptoms and when to worry
• Home remedies for dog constipation
• Bowel obstruction in dogs
• Dog diarrhea

Frequently Asked Questions

How long can a dog go without pooping?

Most dogs poop at least once a day. Call your vet if your dog hasn't had a bowel movement within 48 to 72 hours, or sooner if your dog is straining, vomiting, in pain or not eating.

What causes constipation in dogs?

The most common causes are eating bones, plants, hair or other material that's hard to digest, and not drinking enough water. Diet changes, lack of exercise, some medications, pain, an enlarged prostate, a perineal hernia and nerve or hormone problems can also cause it.

Is dog constipation an emergency?

Usually not, but it can be. Go to a vet right away if your dog is vomiting, lethargic or in pain, may have swallowed an object, or is straining to urinate without producing urine.

How can I tell if my dog is constipated or has a blockage?

A constipated dog strains to pass small, hard stools but is usually otherwise well. A blockage usually causes vomiting, loss of appetite, lethargy and belly pain. If you're unsure, call your vet, because a blockage can quickly become life-threatening.

My dog is straining but nothing comes out. What should I do?

First check whether your dog is trying to poop or pee. Straining to urinate with little or no urine is an emergency. If it's stool, call your vet if it continues, and right away if your dog is also vomiting, lethargic or in pain.

What will a vet do for a constipated dog?

Your vet will examine your dog and may take X-rays and run blood and urine tests. Treatment ranges from diet changes and a vet-prescribed stool softener to fluids, enemas given at the clinic, or removal of the stool under anesthesia.

Can constipation in dogs go away on its own?

Mild constipation often settles with water, fiber and exercise. If it lasts more than a couple of days, keeps coming back or comes with other signs, see your vet.