When your dog has watery diarrhea and keeps straining as if they need to go again, it can be worrying and confusing.
You might wonder whether it’s something they ate or a sign of something more serious brewing in their digestive tract.
We outline the common causes of watery diarrhea and straining in dogs, what you can do at home, and when to seek veterinary help.
Dog Watery Diarrhea and Straining — Why It Happens
Watery diarrhea with straining in dogs is usually caused by irritation or inflammation of the colon, often triggered by infection, diet changes, or swallowed irritants. When the colon becomes inflamed (a condition called colitis), it causes frequent urges to defecate — even when the intestines are already empty. This is why your dog may squat repeatedly and strain without producing much stool.
In some cases, the problem is temporary — such as from eating something unusual or stressful changes. But if the straining continues or the diarrhea becomes more severe, it could point to infection, parasites, or inflammatory bowel disease that requires veterinary attention.
Dog Watery Diarrhea and Straining: Common Causes
1. Colitis (Inflammation of the Colon)
Colitis is one of the most common reasons dogs develop watery diarrhea and strain to defecate.
The colon’s job is to absorb water and store stool. When it becomes irritated — from infection, diet changes, or stress — it stops absorbing water efficiently. The result is loose or watery stool, often mixed with mucus or small streaks of blood.
Dogs with colitis frequently squat and strain because the inflamed colon constantly sends signals that it needs to empty, even when there’s little left inside.
Most cases are acute and resolve within a few days, but chronic colitis can require a special diet and medication to control inflammation.
Read more: Dog Has Watery Diarrhea With Mucus (What it means)
2. Dietary Indiscretion
If your dog recently raided the trash, snuck greasy table scraps, or ate something from the yard, their stomach and intestines may react with watery diarrhea and painful straining.
The digestive system tries to expel the irritant quickly, speeding up intestinal movement — which leads to watery stools. As the colon becomes inflamed in response, your dog might feel a constant urge to defecate, even after passing everything.
While mild cases often resolve on their own, continued straining after diarrhea can lead to irritation or even hemorrhoid-like discomfort around the rectum.
3. Bacterial or Parasitic Infection
Bacteria like Salmonella or Campylobacter, and parasites such as Giardia or Whipworms, can cause watery diarrhea accompanied by straining.
These organisms irritate the intestinal lining, causing inflammation that affects both the small and large intestines. You might notice watery stool that contains mucus, a foul odor, or occasional specks of blood.
Dogs can pick up parasites or bacteria from contaminated water, dirty environments, or other infected animals. Even a single exposure to contaminated puddle water at the park can trigger several days of diarrhea and straining.
If your dog’s diarrhea lasts more than a couple of days or is recurring, your vet may recommend a fecal exam to identify infections and prescribe appropriate deworming or antibiotics.
4. Food Intolerance or Sensitivity
Some dogs develop sensitivities to ingredients like chicken, beef, dairy, or certain grains.
These sensitivities can cause ongoing digestive irritation, leading to watery diarrhea and colonic inflammation — the combination that makes dogs strain repeatedly.
Often, dogs with food sensitivities have intermittent bouts of diarrhea that seem to appear out of nowhere. You may also notice that flare-ups occur after eating specific proteins or treats.
Identifying and removing the offending ingredient through a controlled elimination diet (guided by your vet) can stop the recurring episodes altogether.
5. Stress-Induced Diarrhea
Dogs are emotionally sensitive animals, and their digestive systems often mirror their stress levels.
Travel, boarding, loud noises, or even changes in routine can trigger a rush of stress hormones like cortisol. These hormones speed up gut motility, resulting in watery stools and inflammation of the large intestine.
Because stress-related colitis affects the colon, it often presents with straining and frequent attempts to defecate. Even though the trigger is emotional, the symptoms can look very physical.
Keeping your dog’s environment calm and consistent can prevent stress-induced diarrhea from becoming a recurring issue.
6. Rectal or Anal Irritation
Sometimes, the issue isn’t in the intestines but closer to the end of the digestive tract.
Anal gland impaction, minor rectal inflammation, or irritation from passing watery stool can make dogs feel like they still need to defecate even when they’re done. This causes them to strain repeatedly after each bowel movement.
While mild irritation may resolve with rest and a bland diet, impacted anal glands or rectal inflammation should be checked by a vet — especially if your dog scoots, licks excessively, or cries when trying to poop.
Read more: Dog Watery Diarrhea No Other Symptoms (When to worry)
What to Do If Your Dog Has Watery Diarrhea and Is Straining
When your dog has watery diarrhea and keeps straining, it’s important to act quickly but calmly.
Start by withholding food for 8–12 hours (but not water) to allow the digestive tract to rest. Then offer small portions of a bland diet — boiled chicken or lean turkey mixed with plain white rice or pumpkin puree. These foods are gentle on the gut and help firm up the stool.
Encourage your dog to drink plenty of water, as watery diarrhea can lead to dehydration. You can also add an electrolyte solution made for dogs or offer ice cubes if they’re reluctant to drink.
Avoid treats, table scraps, and fatty foods during recovery, as these can worsen inflammation. Keep your dog’s routine calm and consistent — stress can prolong colitis or cause relapse.
If the straining continues after stools firm up, gently check for irritation around the rectum or signs of anal gland swelling. Persistent straining may mean your dog feels discomfort or has residual inflammation that needs veterinary attention.
Most mild cases improve within 24–48 hours. However, if the diarrhea persists or the straining seems painful, it’s best not to wait it out.
When to Call or Visit Your Vet
Contact your veterinarian right away if your dog’s watery diarrhea lasts longer than two days, contains blood or mucus, or if the straining becomes painful or unproductive.
Seek immediate help if your dog also shows lethargy, vomiting, fever, or loss of appetite, as these can indicate infection or gastrointestinal blockage.
Puppies, senior dogs, and small breeds are particularly vulnerable to dehydration and should be seen promptly if watery diarrhea continues beyond a few hours.
Your vet may perform fecal tests, bloodwork, or imaging to identify infections, inflammation, or blockages. Treatment can include fluids, probiotics, anti-inflammatories, or dietary adjustments depending on the cause.
Read more: Smelly Watery Diarrhea in Dogs (Why it happens and what to do)
Key Takeaway
Watery diarrhea with straining in dogs usually points to irritation in the large intestine — often from diet changes, stress, or infection.
While your dog might seem otherwise fine, continued straining can be painful and signal ongoing inflammation. Provide hydration, a bland diet, and rest for a day or two, but always monitor closely.
If symptoms don’t improve or your dog becomes uncomfortable, don’t delay — your veterinarian can pinpoint the cause and help your pet recover quickly and comfortably.