Why is my dog constipated?

Constipation in dogs matters to owners because it affects comfort, behavior, and daily routines. A dog that strains, seems reluctant to poop, or has a smaller appetite immediately changes how we care for them; what begins as curiosity about an odd stool pattern often becomes real worry when the pet seems uncomfortable or less active. For many people the emotional reaction is strong — you can tell when a dog is tense or hesitant at the door — and practically, untreated constipation may progress to more serious problems such as obstipation or intestinal obstruction. Puppies, elderly dogs, and dogs recovering from surgery are common situations where owners notice constipation more often, and that pattern is worth watching before it becomes a medical emergency.

What’s most likely causing your dog’s constipation?

A straightforward way to think about why your dog might be constipated is to look at things that change how stool moves through the gut or how much water the stool contains. The most frequent causes I see are:

• Recent diet change, a diet low in fiber, or simply not enough water intake.
• Ingested foreign material such as toys, bones, large amounts of hair, or fecal matter that interferes with passage.
• Certain medications (especially some pain medications, antacids, and decongestants), and reduced exercise or pain from arthritis that limits normal movement.
• Neurologic or pelvic issues that reduce nerve or muscle function of the colon.

Any one of these may be the primary driver, and more than one factor is often involved — for example, an older dog on pain medication that also drinks less water and gets less exercise.

How a dog’s digestive system contributes to bowel problems

Understanding what the colon does helps explain constipation. Food is digested in the stomach and small intestine; by the time it reaches the colon most nutrients are already absorbed and what remains is water, fiber, bacteria, and waste. The colon’s role is to absorb water and compact waste into formed stool. If too much water is absorbed or if stool sits too long, the feces become hard and dry and more difficult to pass.

The colon moves material forward using coordinated contractions of muscle controlled by local nerves and the autonomic nervous system. If those contractions are weak, irregular, or disrupted by nerve damage, stool transit slows. Diet and the gut microbiome influence both stool bulk and motility: fermentable fiber can increase bulk and water-holding capacity, while the mix of bacteria may alter gas and stool consistency. Age matters too — older dogs may have slower gut motility or concurrent health problems that reduce appetite and water intake. Breed differences are less dramatic than individual variation, but short-faced breeds or very large breeds can have anatomic or conformation-related tendencies that affect elimination.

When constipation usually appears — age, medications, diet and other triggers

Constipation commonly follows changes in routine or environment. When an owner switches food quickly, the dog may eat less or pass smaller, firmer stools for several days. Travel, boarding, and stress can change both water intake and gut motility, so watch for altered stool patterns after those events. Periods of reduced exercise — for example, after an orthopedic injury or during heavy rain when walks are skipped — also increase risk because physical activity normally helps stimulate bowel movements.

Post-operative periods deserve special attention. Anesthesia and opioid pain medications may slow gut motility, and dogs recovering from abdominal surgery or pelvic trauma might avoid straining because of discomfort. I typically advise close monitoring for the first 48–72 hours after anesthesia and to contact the clinic sooner if your dog hasn’t passed stool in that time or if it seems painful.

Warning signs: when constipation becomes an emergency

Not every slow stooling schedule is an emergency, but several signs do indicate urgent veterinary evaluation. Persistent, forceful straining without producing stool, repeated vomiting, a firm or painful abdomen, or no stool for more than 48–72 hours are reasons to seek help. Bloody or black tarry stool, sudden severe lethargy, collapse, or evidence of dehydration (dry gums, sunken eyes, reduced skin elasticity) are all red flags.

Suspected obstruction — when a dog swallows a toy, bone fragment, or large mass of hair and cannot pass anything — requires immediate attention. An obstruction can progress from constipation to complete blockage and lead to compromised blood flow to the intestine, severe pain, or systemic illness. If you suspect your dog has eaten a foreign object or is getting rapidly worse, don’t wait to see if it improves on its own.

What to do right away if your dog can’t poop

When you first notice constipation, take a calm, methodical approach. Start with simple checks and safe, low-risk actions, then call your veterinarian if there’s no improvement or if danger signs are present.

1. Check hydration and comfort: offer fresh water and note how eagerly the dog drinks; hydrate orally if the dog is willing and not vomiting.
2. Remove access to non-food items that could be swallowed and look for evidence of foreign material in vomit or around the house.
3. Encourage gentle exercise: a short walk or play session can stimulate gut motility in many dogs.
4. Try a short-term, modest fiber boost: a small amount of canned plain pumpkin (not spiced pie filling) or a veterinarian-recommended fiber supplement can help soften stool for a day or two.

Do not use human laxatives, stool softeners, enemas, or suppositories without veterinary guidance — doses and products for people can be harmful to dogs. Call your clinic promptly if your dog is straining for more than one or two bowel attempts, shows pain, vomits, or you suspect ingestion of a foreign body. Your vet can advise whether an office visit, radiographs, or immediate treatment is needed.

Everyday routines that help prevent constipation

Preventing recurrent constipation usually comes down to consistent habits. Feed on a predictable schedule and use a diet with appropriate fiber for your dog’s age and activity level; some dogs do better on higher-fiber adult maintenance diets while others need only a small supplemental fiber source. Keep fresh water available at all times — I often recommend multiple water bowls around the house or a water fountain for dogs that drink less at a single bowl.

Daily exercise helps maintain normal bowel motility. For aging or arthritic dogs, adjust activity so short, frequent walks replace longer sessions. Monitor chewable items and bones: avoid small, easily fragmented bones or very hard chews that might produce fragments. Long-haired breeds or dogs that groom themselves excessively may form hairballs or ingest fur; regular grooming reduces that risk.

Lastly, review medication side effects with your veterinarian. If a drug that contributes to constipation is necessary, sometimes an alternative medication, dose adjustment, or preventive fiber strategy can reduce the problem. Keep a simple log of stool frequency, consistency, and any changes in diet or activity — a few days of notes can be very helpful during a clinic call.

Vet-recommended products and supplies to relieve constipation

Certain items make prevention and management easier. A pet water fountain or several nonspill bowls encourages drinking and can be particularly helpful for dogs that don’t like still water. For long-term fiber support, vet-formulated high-fiber diets or a psyllium-based supplement recommended by your veterinarian can normalize stool bulk without causing sudden, dramatic changes.

Over-the-counter stool softeners and laxatives made specifically for pets exist, but these should be used only under veterinary guidance because of dosing differences and potential side effects. Rectal supplies such as lubricants or glycerin suppositories should not be used unless a veterinarian instructs you; improper use can cause injury. Finally, an accessible crate or mat near the door for senior dogs and a harness or ramp for dogs with mobility issues can reduce the reluctance to move and help maintain regular elimination.

References and trusted sources

• Merck Veterinary Manual: “Constipation and Obstipation in Dogs” — Merck Sharp & Dohme Corp.
• Ettinger, S.J., Feldman, E.C., “Textbook of Veterinary Internal Medicine: Diseases of the Gastrointestinal Tract” — Elsevier.
• American Veterinary Medical Association (AVMA): “Postoperative Care and Pain Management in Small Animals” guidance documents.
• World Small Animal Veterinary Association (WSAVA) Global Nutrition Toolkit: recommendations on water, fiber, and diet transitions.
• American College of Veterinary Emergency and Critical Care (ACVECC): resources on foreign body obstruction and emergency management.