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Why Does My Dog Have Diarrhea At Night?

Is your dog suffering from bouts of diarrhea or loose stools at night?

Are you concerned that these occasional or frequent occurrences may be a sign of a yet undiagnosed health condition?

Doggie diarrhea, especially at night, is definitely no laughing matter.

Not only does this cause your dog to suffer unnecessarily, it can also lead to big messes within the home, especially if you are asleep when these urges happen and your dog has no way of getting himself outside.

To help you understand—and hopefully bring an end—to these nocturnal bouts of diarrhea in your dog, below we will discuss several reasons why this may occur, and highlight some of the steps you can take to address these causes.

Why Does My Dog Have Diarrhea at Night?  The Reasons and How to Address Them

Diarrhea is a very unpleasant and sometimes maddening condition, one characterized by loose, watery bowel movements—bowel movements that tend to occur more frequently than usual.

The condition is fairly common in dogs, usually short-lived and tends to resolve itself after a day or two.

Often, the cause of this diarrhea is benign and not cause for great concern, but in other cases, diarrhea may be just one of the disagreeable symptoms pointing to a larger and more serious health condition.

Loose, watery stools may be just one of many symptoms of diarrhea in dogs.

Other symptoms of diarrhea include:

  • Increased volume.  Because of the watery nature of diarrhea, the volume of stool may also be increased.
  • Accidents.  The “urge to defecate” that often accompanies diarrhea can lead to potty accidents inside the home.
  • Straining.  This same “urge” can also cause fecal straining.
  • Presence of blood or mucus.  The presence of blood or mucus in your pet’s feces may signify a more serious health condition.

The exact causes of nighttime diarrhea in dogs are virtually limitless, as diarrhea is a common symptom for many different health conditions—conditions whose seriousness ranges from mild to potentially fatal.

Some of the more severe health conditions (like pancreatitis) that include diarrhea as one of the potential symptoms, may also cause additional symptoms to watch for—symptoms such as lethargy, vomiting, mild to severe pain, weakness, and depression.

Although listing and describing every single cause or condition that could possibly lead to nighttime diarrhea would take several pages, here we have coalesced some of the more common reasons for its occurrence in dogs, and some advice on addressing each reason.

Changes in Diet

If you were to eat the same exact food, day after day, morning and night, for your entire existence, how do you suppose your gastrointestinal system might react if you decided to sample something new?

Not great, right?

Well, that is exactly the situation in which some dogs find themselves when their owner switches foods/brands.

Just like their human counterparts, dogs can grow accustomed to certain types of food, whether wet food or kibble.

And when that food selection is suddenly altered, their intestinal system may stage a revolt in the form of diarrhea.

When dietary changes are the cause of nighttime diarrhea in dogs, the situation is usually temporary and tends to work itself out.

Eventually your dog will grow accustomed to his new food and the problem will cease, provided the new dog food is not tainted in some way.

If you need to make changes to your dog’s diet, either because of cost factors or health issues, and if you want to avoid nocturnal diarrhea of this type, consider making the gradual changes to your dog’s diet, rather than sudden ones.

Mix in just a small portion of the new or different food, and steadily increase this portion over time until it becomes the sole source.

Parasitic Infections

Parasitic infection in dogs, specifically the presence of intestinal worms, is one of the most common causes of diarrhea at night.

Dogs can pick up intestinal worms—hookworms, pinworms, roundworms, tapeworms, etc.—in a variety of ways.

Some dogs can ingest the worms that might be present in soil or feces, while still others might acquire them through larvae that enters the skin.

Puppies and younger dogs are more susceptible to worms, with some getting them through their mother’s milk as they feed.

Whatever the method of entry, once inside your dog’s intestines they can wreak a lot of havoc on that system, including causing diarrhea.

Worms/parasites latch onto the walls of the large and small intestines and feed on undigested food and blood.

And the more they multiply, the more harm they cause.

These parasitic infections can lead to malnutrition and bleeding inside the intestines, which is why blood may often be seen within the diarrhea of dogs.

Parasites cause diarrhea in dogs through a process called “over-secretion.”

In other words, when these worms are present, the intestines secrete an overabundance of fluid as they attempt to fight off things like bacteria, toxins and parasites.

And it is this excess fluid that leads to frequent and watery stools.

If you fear worms or other parasites may be causing the overnight diarrhea in your dog, be sure to make an appointment with the vet.

There are many medications that work great to kill off these pests and restore your pooch’s gut to normal.

Food Allergies and Sensitivity

Food allergies and/or food sensitivity could also be the culprit behind your dog’s nocturnal diarrhea.

This is a very common cause for stray dogs and outside dogs that are known to root through trash cans at night.

Normally, you would know right away if the regular pet food you are giving to your dog is not agreeing with him.

Therefore, it is doubtful this is the problem.

However, it is very likely to happen in dogs who are fed “people food,” and for dogs who root through garbage cans for scraps.

Naturally, the same type of food that may cause stomach upset and diarrhea in some humans—food like dairy or gluten and spoiled food—can also cause the same problems in dogs.

For this reason, it is not recommended you feed your dog with table scraps, and you should definitely keep him away from trash cans where the food within may be rotted or tainted.

Illness and Medication

There are many, many illnesses and some medications that can bring about nighttime diarrhea in dogs.

In cases such as these, the diarrhea is a physical, biological symptom meant to protect the body from what ails it.

A brief, albeit incomplete, list of illnesses and conditions that can cause diarrhea in dogs includes:

  • Intestinal blockages
  • Systemic or intestinal infections (viral, bacterial and fungal infections)
  • Pancreatitis
  • Kidney disease
  • Liver disease
  • Rickettsia (a tick-borne disease)
  • Addison’s disease

Finally, several medications, especially those used to treat parasitic, bacterial and viral infections, can also cause nightly diarrhea in dogs during some or the entire course of the prescription.

Antibiotics, especially, can lead to these watery and urgent stools.

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