Why Is My Dog Having Diarrhea?

What Pet Owners Need to Know

At Gilbert Queen Creek Emergency Veterinarian & Specialty Center, we know how unsettling it is to see your dog sick, especially when they’re dealing with diarrhea. It’s messy, smelly, and sometimes a sign of something more serious. Pet owners often ask us: “Why is my dog having diarrhea?” – and we’re here to help you understand when it’s okay to wait and when it’s time to call for help.

While many cases of diarrhea are mild and resolve quickly, others can indicate an underlying medical problem. For small breed dogs and puppies, diarrhea can be dangerous, leading to low blood sugar (hypoglycemia) or dehydration, which can become life-threatening without veterinary care. And if you ever notice blood in your dog’s diarrhea, that’s always a reason to contact your veterinarian right away.

Here’s a breakdown of the most common causes of diarrhea in dogs:

1. Eating Something They Shouldn’t (Dietary Indiscretion) Dogs are natural explorers, and sometimes that curiosity leads them to eat things they shouldn’t, like garbage, spoiled food, or snacks found outside. This is often called “garbage gut” and is a top reason dogs develop digestive upset.

Signs to look for:

• Loose or watery stool
• Occasional vomiting
• Normal playful behavior otherwise

Mild cases can often improve with a bland diet (boiled chicken and rice) and hydration. But if your dog’s diarrhea persists, or they show other symptoms, give us a call.

1. Sudden Food Changes Even switching to a better-quality food too quickly can upset your dog’s digestion. Gradual transitions over 7–10 days help avoid tummy troubles.
2. Parasites such as roundworms, hookworms, giardia, or coccidia are common culprits, especially in puppies, new rescues, or dogs who visit dog parks. Some parasites can also infect humans, so prompt diagnosis and treatment are important.

Our clinic can run a fecal test to check for parasites and help your dog recover quickly.

1. Infections: Bacteria or Viruses Infectious diarrhea can develop rapidly and often comes with vomiting, lethargy, or fever. Immediate veterinary care is recommended, especially for puppies. Possible causes include:

• Parvovirus
• Distemper
• Salmonella, Campylobacter
• Clostridium
• Tick-borne infections (Anaplasmosis)

1. Food Sensitivities or Allergies Some dogs have food intolerances that cause chronic or recurring diarrhea. Other signs may include:

• Itchy skin or paws
• Ear infections
• Frequent licking or chewing

We can help guide you through food trials or recommend prescription diets.

1. Stress-Induced Diarrhea: Stress can trigger diarrhea in dogs, just like in people. This is usually temporary but can be uncomfortable.

Common stressors include:

• Boarding or daycare
• Loud noises (thunder, fireworks)
• Changes in routine or environment
• Travel

If stress is the cause, we can recommend calming strategies, supplements, or medications.

1. Chronic Illness or Inflammatory Conditions Persistent or recurrent diarrhea may signal a chronic issue such as:

• Inflammatory Bowel Disease
• Pancreatitis
• Liver or kidney disorders
• Addison’s disease
• Cancer

Further testing, bloodwork, imaging, or biopsies can help identify these conditions.

1. Ingesting Foreign Bodies or Toxins Dogs sometimes swallow things they shouldn’t, like toys, bones, sticks, or human foods, that can cause blockages or toxicity.

Common culprits:

• Toxic plants (Sago Palm, Oleander)
• Chocolate
• Grapes or raisins
• Xylitol (in sugar-free gum or peanut butter)
• Marijuana or vape pens
• Bufo toad secretion

Some objects require surgical removal, so don’t wait to seek care if you suspect ingestion.

1. Vaccine or Medication Reactions Occasionally, dogs can have allergic reactions to vaccines or medications. Diarrhea may be accompanied by:

• Vomiting
• Hives or swelling
• Lethargy

If you see these signs, call immediately.

1. Parvovirus & Distemper: Deadly Threats in Puppies Both parvovirus and distemper are highly contagious and life-threatening. Signs include:

• Bloody diarrhea
• Vomiting
• Lethargy
• Seizures or neurological symptoms (with distemper)

These diseases are preventable with vaccines, but if symptoms arise, emergency care is critical.

When Should You Call Us? Reach out to us right away if your dog shows:

• Diarrhea lasting more than 24 hours
• Vomiting with diarrhea
• Blood in the stool
• Weakness or refusal to eat

How We Diagnose Diarrhea: We may recommend:

• Fecal testing for parasites and infections
• Parvo testing
• Bloodwork to check organ function
• Imaging (X-rays, ultrasound)
• Disease-specific testing (Lyme, Distemper)

Treatment Options: Once we diagnose the cause, we may recommend:

• IV fluids for hydration
• Deworming medication
• Hospitalization for parvo or severe cases
• Bland diets or prescription food
• Probiotics
• Medications like anti-nausea, antibiotics, or anti-inflammatory drugs

We’re Here to Help 

At Gilbert Queen Creek Emergency Veterinarian & Specialty Center, your dog’s health is our priority. If you’re worried about diarrhea, or anything else, we’re here to help get your pet feeling better fast. Call us anytime for advice or to schedule a visit.