Smelly Diarrhea in Dogs

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A healthy dog has poops that are moist but solid, are chocolate brown in color, and keep their shape. Dog owners can keep tabs on their pet health by noticing changes in their dog's stools, especially with soft stools. Diarrhea is defined as loose stools with frequent bowel movements.


don't feed your dog table scraps.
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Foul-smelling diarrhea is always a cause of concern because it can signify underlying health conditions, including common causes, like bacterial infections; diseases, like parvovirus and Giardia; infected anal sacs; intestinal parasites; food intolerance; or other dietary issues. Always take puppies and dogs to the veterinarian for an examination, especially because some diseases causing diarrhea can be fatal.


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Why does my dog have smelly diarrhea?

Smelly diarrhea can be caused by a variety of issues, including infection, parasites, a virus, or even a change in diet.‌ Take note of other characteristics of the diarrhea, such as its color, consistency, and whether the stool sample contains blood.


Infected anal sacs

If your dog has diarrhea and smells like fish, it could be a sign of problems using the anal sacs when pooping. Dogs have anal sacs (also known as anal glands) on either side of their anus. These anal sacs naturally produce smells, including a fishy smell, that dogs use to mark their territory. But the odor may become stronger when there is a health problem present. Anal sacs can become infected or impacted (when the anal sacs don't fully empty and fluid dries within them), or they can have tumors.


If your dog has diarrhea and a strong fishy odor, a veterinarian may need to express (empty) the anal sacs manually. Veterinarians and groomers know how to express anal sacs, and veterinarians can determine the exact problem.

A dog's digestive tract gets used to being on the same dog food, and dietary changes can lead to digestive system issues with foul-smelling results. Dogs may have diarrhea when switching kibble brands or in response to eating something they shouldn't.


Food allergies can also cause digestive issues in dogs. Your veterinarian may want to switch your dog to a special veterinary diet, sometimes referred to as a prescription diet.

A lot of human foods can cause gastrointestinal problems in dogs since they are difficult to digest, so don't add table scraps or fatty foods to your dog's diet. Dogs who are fed fatty foods can develop pancreatitis. Unfortunately, dogs love to fetch their own "treats" out of the trash and consume whatever foods they can get, so try to keep food out of their reach. Eating foreign objects can also lead to a case of diarrhea.



Parvovirus in dogs

A dog infected with parvovirus will have smelly diarrhea feces that may have blood or mucus in it. Parvo is a disease that's passed from the poop of infected dogs or items contaminated with the poop (like shoes, feet, and clothing). All unvaccinated dogs are at risk for parvovirus. Puppies under the age of 5 months are the most at risk and the hardest to treat.


Most dogs with parvovirus will recover as long as they get appropriate treatment. In addition to diarrhea, watch out for:

  • Vomiting
  • Loss of appetite
  • Restlessness
  • Fever


Take your dog to the veterinarian if you notice diarrhea that's smelly. There's no cure for parvo, but dogs can survive with veterinary care. Certain dog breeds have a higher risk of fatality from parvo, including:

  • Rottweilers
  • Doberman pinschers
  • German shepherds
  • Pit bulls
  • English springer spaniels

Giardia in dogs

While many dogs with Giardia don't have diarrhea, this parasite can cause older adult dogs and puppies to have watery diarrhea. Dogs can become infected with this parasite by drinking contaminated, stagnant water, like from a puddle or a shared dog bowl.

Dogs with Giardia may have persistent or intermittent diarrhea that smells horrible. Their poop will be soft and watery, may contain blood, and may look green. Giardiasis isn't typically fatal except in dogs with an immunocompromised immune system, but it does need to be treated by a veterinarian.

Dietary changes can lead to foul-smelling results.
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Other causes of smelly diarrhea

In addition to the causes listed above, other causes of diarrhea that smells bad include:


  • Inflammatory bowel disease
  • Pancreas issues
  • Coronavirus
  • Distemper

Treatment for smelly dog diarrhea

Treatments vary depending on the severity of the diarrhea and what is causing it. For mild cases, you may be advised to refrain from feeding your dog for 24 hours and let the body heal itself without trying to digest food. The veterinarian may instead prescribe a special diet to feed in small amounts.

If diarrhea persists or is severe, your veterinarian may order tests to help with diagnosis, such as:

  • Bloodwork
  • Rectal exam and stool samples
  • Bacterial culture
  • X-rays
  • Ultrasound
  • Endoscopic exam
  • DNA testing

When the tests reveal a cause that has known treatments, your veterinarian will prescribe the appropriate medication, such as a dewormer for parasites or antibiotics for bacterial infections. Dogs with diarrhea can become severely dehydrated, so their treatment could involve hospitalization to administer fluids.

How to prevent smelly, watery diarrhea in dogs

To protect puppies from parvovirus, make sure that they are up to date on their vaccinations. During the time when puppies aren't fully vaccinated, be careful when taking them to public areas, such as dog parks.

Additionally, never allow your dog of any age to drink from puddles and avoid communal dog bowls by having a fresh source of water on hand. Never allow your dog to touch other dogs' poop, as it can contain all kinds of diseases and intestinal parasites, like hookworms, roundworms, and parvovirus, all of which can cause stomach upset and diarrhea.

Puppies are especially vulnerable to diseases characterized by smelly diarrhea.
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When to see a veterinarian about my dog's poop

Whenever diarrhea is smelly, dogs need to be seen by a veterinarian. Diarrhea is a symptom of many illnesses and should always be taken seriously. Diarrhea can become a serious issue even in mild cases because it can lead to severe dehydration if fluids aren't replenished. If your dog's diarrhea is bloody or is accompanied by other symptoms, like vomiting, a lack of appetite, fever, abdominal pain, weakness, and other health issues, speak with your veterinarian.


Veterinarians may ask for a sample, so collect fresh diarrhea with a poop bag before your appointment. Veterinarians will work to determine what's causing the diarrhea, so they may run fecal tests, blood tests, and X-rays to make a diagnosis. Treatment will depend on the underlying issue but may include medication, dietary changes, and intravenous fluids if your dog is dehydrated.

The bottom line

Dogs can have smelly diarrhea for numerous reasons. Some diarrhea may clear up on its own, but other dogs will need veterinary treatment and possibly medication and/or a special diet. For severe or prolonged diarrhea, cases of blood in the stool, and even mild diarrhea that persists, contact your dog's veterinarian. Diarrhea causes loss of fluids, and your dog may become dehydrated even with milder cases. Watch for symptoms in addition to diarrhea, especially when blood is present or your dog's behavior is out of character.


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