Our Veterinary Team Explains Common Causes and When to Worry
At Bell Parkway Veterinary Hospital, one of the most common concerns we hear from pet owners is: “Why does my dog have diarrhea?”
We completely understand how distressing it can be when your beloved dog isn’t feeling well. Diarrhea is messy, uncomfortable, and can be concerning. While many cases are mild and clear up easily, others may point to a more serious issue that requires veterinary care. In some situations, especially with small puppies or toy breeds, even brief episodes of diarrhea can cause hypoglycemia (low blood sugar), which may need emergency care. If you ever notice blood in your dog’s diarrhea, it’s time to call your vet right away.
Our goal is to help you recognize the most common causes of diarrhea in dogs, know what signs to look for, and understand when it’s best to seek veterinary help.
- Dietary Indiscretion (Eating Something They Shouldn’t)
Dogs are naturally curious and often explore the world with their mouths. Unfortunately, this sometimes leads them to eat things they shouldn’t, like table scraps, garbage, spoiled food, or something they find outdoors.
This is often called “garbage gut” and is one of the leading reasons dogs develop temporary stomach upset and diarrhea.
What you might notice:
- Loose or watery stool
- Possible vomiting
- Otherwise acting playful and normal
Mild cases may improve with a bland diet (like boiled chicken and rice) and access to fresh water. However, if your dog’s symptoms last more than a day or two, or they seem uncomfortable, it’s best to call us.
- Sudden Changes in Diet
Switching your dog’s food too quickly, even to a healthier option, can upset their digestive system. Dogs need time to adjust because their gut bacteria must adapt. To help prevent this, we recommend transitioning slowly over 7–10 days by mixing increasing amounts of the new food with the old.
- Parasites
Intestinal parasites such as roundworms, hookworms, giardia, or coccidia can all cause diarrhea, particularly in puppies, newly adopted dogs, or dogs that visit parks, daycares, or kennels. Some parasites are even zoonotic, meaning they can spread to humans.
Our clinic can perform a fecal ova and parasite test to detect parasites and guide treatment. Untreated parasites can lead to more serious issues like nutritional deficiencies and anemia.
- Infections: Bacterial or Viral
Dogs, like people, can develop infections that result in diarrhea. Often, these are accompanied by vomiting, fever, lethargy, or appetite loss. In young puppies especially, these infections can escalate rapidly, so please reach out right away. Infections may include:
- Parvovirus (especially dangerous in puppies and unvaccinated dogs)
- Distemper Virus
- Bacterial infections like Salmonella or Campylobacter
- Clostridium overgrowth
- Anaplasmosis (tick-borne infection)
- Food Intolerances and Allergies
Some dogs are sensitive to certain foods such as chicken, beef, grains, or dairy. This sensitivity can lead to chronic or recurring diarrhea. You may also notice:
- Skin irritation
- Ear infections
- Itchy paws or face
Our veterinary team can help you with an elimination diet trial or recommend prescription hypoallergenic diets to get to the bottom of the issue.
- Stress and Anxiety
Just like people, dogs can get diarrhea from stress. Anxiety can lead to temporary gastrointestinal upset known as stress colitis. We can recommend calming strategies, supplements, or medications if your dog struggles with anxiety. Common stress triggers include:
- Boarding, Doggy Day Care, and Pet Resorts
- Separation Anxiety when left alone
- Moving homes or changes in routine
- Loud noises (fireworks, storms)
- Travel
- Chronic Conditions and Inflammatory Diseases
For dogs with frequent diarrhea, vomiting, or weight loss, more advanced diagnostics like bloodwork, imaging, or biopsies may be needed. Chronic diarrhea may signal conditions such as:
- Inflammatory Bowel Disease (IBD)
- Pancreatitis
- Liver or kidney disease, renal failure, or liver shunts
- Chronic Idiopathic Hepatitis
- Addison’s disease (hypoadrenocorticism)
- Immune-Mediated Thrombocytopenia
- Cancer
- Foreign Body Ingestion or Toxin Ingestion
Diarrhea can be a warning sign that your dog has swallowed something they shouldn’t. Pets sometimes ingest items like string, socks, sticks, toys, or human food items that can’t pass through the digestive tract. Some swallowed objects, like old pennies or lead, can cause toxicity, while others can cause physical blockages or intestinal damage. Strings, in particular, can lead to dangerous perforations.
While some objects may pass on their own, many become lodged and require surgical removal through a gastrotomy or enterotomy.
Items that commonly cause toxicity and diarrhea include:
- Toxic Plants (Oleander, Sago Palm)
- Marijuana or Vape Pens
- Chocolate (especially dark chocolate)
- Xylitol (in sugar-free gum, peanut butter, and other products)
- Grapes or Raisins
- Bufo Toad Secretion (Marine or Sonoran Desert Toad)
- Allergic Reactions to Vaccines or Medications
Occasionally, vaccines or medications can trigger allergic reactions in dogs, sometimes resulting in diarrhea along with symptoms such as:
- Vomiting
- Lethargy
- Facial swelling
- Hives
- Intense itching
If you notice any of these signs after your dog receives a vaccine or new medication, contact your vet immediately.
- Parvovirus & Distemper (Common in Puppies)
Canine Parvovirus is a highly contagious virus attacking the gastrointestinal tract, causing bloody diarrhea, vomiting, lethargy, fever, and appetite loss. Without prompt treatment, it can be fatal. The virus spreads through direct contact or contaminated surfaces but is preventable with routine vaccination. Even with care, not all dogs survive, though hospitalization significantly improves outcomes.
Canine Distemper is another serious viral disease that affects the respiratory, gastrointestinal, and nervous systems. Puppies under four months and unvaccinated dogs are most at risk. Signs include eye discharge, nasal congestion, coughing, diarrhea, vomiting, seizures, and even paralysis. Distemper is often fatal, and survivors can suffer lifelong neurological damage.
When Should You Call the Vet?
Deciding when to wait or seek help isn’t always easy. If you’re ever unsure, we’re here to offer guidance. Call us if your dog has:
- Diarrhea lasting more than 24 hours (or sooner if other symptoms appear)
- Blood in the stool (bright red or tarry black)
- Vomiting along with diarrhea
- Lethargy, weakness, or signs of pain
- Refusal to eat or drink
What Diagnostics Can Help Determine the Cause?
To find the underlying cause of your dog’s diarrhea, we may recommend:
- Fecal Analysis for Ova & Parasite Screening
- Giardia Testing
- Parvo Testing
- Fecal PCR (for early infection detection)
- Complete Blood Count & Chemistry Panel to assess organ function
- Bile Acids Testing or Liver Biopsy
- X-rays to look for foreign bodies or masses
- Ultrasound to examine abdominal organs
- Anaplasma or Lyme Testing
- Distemper PCR Testing
How We Can Help: Diarrhea Treatment Options
At Bell Parkway Veterinary Hospital, we know your dog is family. Whether the problem is minor or serious, we’re here to provide compassionate, comprehensive care.
Treatment options may include:
- IV Fluids for hydration
- Deworming with Panacur or Drontal
- Parvo Treatment and Hospitalization
- Temporarily withholding food
- Bland Diets (Chicken & Rice or prescription options like Hills I/D, Hills A/D, Purina EN, Royal Canin GI)
- Nutritional Supplements and Vitamins
- Probiotics such as Fortiflora
- Medications like Cerenia, Famotidine, Metoclopramide, Metronidazole, Kaopectate, Clavamox, or Convenia (depending on diagnosis)
If you have any questions or concerns about your dog’s diarrhea, don’t hesitate to reach out. We’re here to help your pet feel better and get back to their happy, healthy self.
