Understanding Dog Diarrhea and Straining

1. Colitis (Inflammation of the Colon)

One of the most common causes of dog diarrhea and straining is colitis, an inflammation of the large intestine.

Colitis in dogs often results in frequent, small-volume diarrhea, accompanied by mucus or blood in the stool and visible discomfort while defecating.

Colitis can be triggered by:

• Stress

• Parasites

• Bacterial infections

• Sudden dietary changes

Dogs with colitis often squat repeatedly, strain, and pass little stool each time. You might see your dog pacing, whining, or looking anxious after attempting to go.

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2. Parasitic Infections

Intestinal parasites such as whipworms, hookworms, giardia, and coccidia can cause both diarrhea and straining in dogs. These parasites irritate the gastrointestinal lining, especially the colon, leading to loose stools, discomfort, and frequent urges to defecate.

Puppies and dogs in group environments (like shelters or boarding facilities) are especially vulnerable. Infected dogs may show additional signs like:

• Weight loss

• Dehydration

• Vomiting

• Poor coat condition

Routine fecal exams can detect these parasites, and appropriate deworming or antiparasitic treatments are highly effective.

Related: Dog diarrhea and scooting (Explained)

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3. Dietary Indiscretion or Sudden Diet Change

Dogs are notorious for eating things they shouldn’t—spoiled food, trash, table scraps, or even foreign objects. This is called dietary indiscretion, and it’s a frequent cause of diarrhea and straining in dogs.

Even a sudden switch in your dog’s food without proper transition can cause gastrointestinal upset. When this happens, the colon may become irritated, triggering diarrhea followed by straining due to inflammation and frequent urges.

If you’ve recently changed your dog’s diet, try reverting to their old food or transitioning more slowly over 7–10 days to minimize stress on their digestive system.

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4. Food Allergies or Intolerances

Food allergies or intolerances may also lead to dog diarrhea and straining, especially if your dog has trouble digesting certain ingredients like beef, dairy, wheat, or chicken.

The reaction causes inflammation in the gut, leading to chronic diarrhea, gas, bloating, and straining. Dogs with food sensitivities may also show signs of:

• Itchy skin

• Ear infections

• Chronic licking or biting

• Poor growth (in puppies)

Your vet may recommend an elimination diet or hypoallergenic food trial to pinpoint the problematic ingredient.

Related: Dog diarrhea and leg pain (Explained)

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5. Infections (Bacterial or Viral)

Pathogens such as Salmonella, E. coli, or canine parvovirus can trigger acute diarrhea and straining in dogs. These infections often lead to bloody, foul-smelling stool, lethargy, and vomiting.

Parvovirus, in particular, is highly contagious and life-threatening, especially in puppies or unvaccinated dogs. It causes severe intestinal inflammation, resulting in diarrhea, vomiting, fever, and dehydration.

If you suspect an infectious cause, isolate your dog and seek immediate veterinary care.

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6. Stress and Anxiety

Stress can manifest in many physical ways in dogs, including diarrhea and straining. Stress-induced colitis is especially common in:

• Newly adopted dogs

• Dogs moved to a new environment

• Pets exposed to loud noises or unfamiliar people/animals

The stress hormones released in such situations disrupt the normal balance of gut bacteria and increase colon motility, leading to inflammation and urgent, strained bowel movements.

Providing a calm, predictable environment can often help alleviate symptoms. In more severe cases, your vet may recommend probiotics or anti-anxiety medications.

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7. Obstruction or Foreign Body

When a dog swallows a non-digestible object, it can become lodged in the intestines or colon, partially blocking the passage of stool. This can cause diarrhea (as liquid stool passes around the blockage) followed by straining due to the obstruction.

Signs of an obstruction include:

• Repeated straining with little to no stool

• Vomiting

• Abdominal pain or bloating

• Refusal to eat

This is a medical emergency and often requires X-rays and possible surgical intervention.

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8. Anal Gland Problems

If your dog is showing signs of straining, scooting, or licking their rear, they may have impacted or infected anal glands. These glands, located on either side of the rectum, help dogs mark territory but can sometimes become blocked.

Impacted anal glands can cause painful defecation, leading to straining and diarrhea if irritation affects the lower colon.

A vet can manually express the glands or treat any infections present.

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9. Inflammatory Bowel Disease (IBD)

Chronic cases of dog diarrhea and straining may point to inflammatory bowel disease, a long-term condition in which the intestines become chronically inflamed.

Dogs with IBD often have:

• Chronic diarrhea (sometimes with mucus or blood)

• Straining to defecate

• Weight loss

• Vomiting

• Poor appetite

IBD is typically managed with dietary changes, medications like corticosteroids, and long-term vet monitoring.

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When to Worry: Signs You Need to See a Vet

While a single bout of diarrhea isn’t always cause for alarm, persistent dog diarrhea and straining should be evaluated by a veterinarian—especially if you notice:

• Blood or mucus in the stool

• Repeated, unproductive straining

• Vomiting

• Lethargy or collapse

• Signs of abdominal pain

• Loss of appetite or weight

• Dehydration (dry gums, sunken eyes, skin tenting)

Puppies, senior dogs, or those with underlying medical conditions are more vulnerable and should be seen as soon as symptoms arise.

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What You Can Do at Home

If symptoms are mild and your dog is otherwise acting normal, here are some at-home tips you can try:

1. Fast your dog for 12–24 hours (adults only, not puppies).

2. Reintroduce bland food such as boiled chicken and white rice in small meals.

3. Ensure clean, fresh water is always available.

4. Monitor for worsening symptoms like vomiting or bloody stool.

5. Avoid giving human medications without veterinary guidance.

If no improvement is seen within 24–48 hours—or symptoms worsen—call your vet immediately.

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Key Takeaway: Dog Diarrhea and Straining

Dog diarrhea and straining can stem from a wide range of causes, from mild dietary indiscretions to serious conditions like infections, colitis, or obstructions.

While occasional symptoms may resolve on their own, persistent or severe diarrhea and straining in dogs need prompt veterinary evaluation.

Early intervention, proper diagnosis, and targeted treatment are crucial in helping your dog feel better and preventing complications.

By paying close attention to their bowel habits and overall health, you can help ensure your furry friend stays happy and healthy.