Diarrhea in Dogs and Cats: When Should You See the Vet?

What Causes Diarrhea in Dogs and Cats?

Diarrhea occurs when the gastrointestinal tract isn't properly absorbing water or nutrients. There are many possible causes, including:

Eating something they shouldn't
Sudden diet changes
Table scraps or high-fat foods
Stress
Intestinal parasites
Bacterial or viral infections
Food allergies or intolerances
Pancreatitis
Inflammatory bowel disease
Certain medications
Liver or kidney disease
Cancer
Foreign objects or intestinal obstruction

Sometimes the cause is relatively minor, while other cases require treatment and diagnostic testing.

When Should I Take My Pet to the Vet for Diarrhea?

A healthy adult dog or cat with one or two mild episodes of diarrhea who is otherwise acting completely normal may be able to be monitored initially.

However, contact your veterinarian if the diarrhea is severe, persistent, or accompanied by other symptoms.

Your pet should be evaluated if:

Diarrhea lasts more than a day or two
There are multiple episodes of diarrhea in a short period
Your pet has a large amount of watery diarrhea
There is blood in the stool
The stool is black or tarry
Your pet is vomiting as well
Your pet refuses food or water
Your pet is lethargic, weak, or acting unusually
Your pet appears to be in pain
Your pet is losing weight
Your pet has a fever
Your pet is showing signs of dehydration
Your pet is very young, elderly, or has other medical conditions

If your pet seems significantly ill, don't wait for the diarrhea to resolve on its own.

What Does Blood in the Stool Mean?

Blood in the stool can look different depending on where it originates.

Bright red blood generally comes from the lower gastrointestinal tract. Small amounts of bright red blood can occur with inflammation or irritation of the colon and may be seen with conditions such as colitis.

Black, tarry stool can indicate digested blood coming from higher in the gastrointestinal tract and is more concerning.

Blood in the stool doesn't always mean your pet has a life-threatening problem, but it is a reason to contact your veterinarian—especially if there is a large amount of blood or your pet is also vomiting, lethargic, painful, or not eating.

Diarrhea Can Cause Dehydration

One of the biggest concerns with significant diarrhea is dehydration.

This is particularly important in puppies, kittens, small dogs, and elderly pets, which can become dehydrated more quickly.

Signs of dehydration may include:

Dry or sticky gums
Weakness or lethargy
Decreased urination
Loss of skin elasticity
Sunken-looking eyes

If your pet has frequent watery diarrhea and isn't drinking normally, veterinary attention may be needed to prevent or treat dehydration.

What About Puppies and Kittens?

Diarrhea in puppies and kittens deserves extra attention.

Young pets can become dehydrated and weak more quickly than healthy adult animals. They are also more susceptible to certain intestinal parasites and infectious diseases.

If a puppy or kitten has significant or persistent diarrhea, isn't eating, is vomiting, or seems lethargic, contact your veterinarian promptly.

Your veterinarian may recommend a fecal examination to look for intestinal parasites and other causes of gastrointestinal disease.

Why Does My Pet Keep Getting Diarrhea?

If your pet has diarrhea repeatedly, it's important to look for an underlying cause rather than treating each episode individually.

Recurring diarrhea may be associated with:

Food sensitivities
Intestinal parasites
Chronic intestinal inflammation
Pancreatic disease
Chronic infections
Liver or kidney disease
Other systemic illnesses

Your veterinarian may recommend fecal testing, bloodwork, dietary trials, abdominal imaging, or other diagnostics depending on your pet's age and symptoms.

Should I Bring a Stool Sample?

If you're bringing your pet to the veterinarian for diarrhea, bringing a fresh stool sample can be very helpful.

A fecal examination can identify several common intestinal parasites that may cause diarrhea. Even pets that seem otherwise healthy can carry parasites, so routine fecal testing is an important part of preventive care.

Place a fresh sample in a clean, sealed container or bag and bring it with you if possible. Your veterinary team can tell you if there are specific collection instructions.

Can I Treat My Pet's Diarrhea at Home?

For a mild episode in an otherwise healthy adult pet, your veterinarian may recommend monitoring, dietary changes, or other supportive care.

However, don't give your pet over-the-counter human medications unless your veterinarian specifically tells you to do so. Some medications that are safe for people can be harmful to dogs or cats, and certain medications can make some underlying conditions worse.

If diarrhea is severe, persistent, or accompanied by vomiting, pain, lethargy, blood, or loss of appetite, your pet should be evaluated rather than simply treated at home.

When Is Diarrhea an Emergency?

Seek urgent veterinary care if your pet has diarrhea along with:

Significant weakness or collapse
Severe abdominal pain or swelling
Repeated vomiting
Large amounts of blood in the stool
Black, tarry stool
Signs of severe dehydration
Inability to keep water down
Pale or white gums
Suspected toxin ingestion
Suspected ingestion of a foreign object

These signs can indicate a more serious problem that requires immediate treatment.

Don't Ignore Persistent Diarrhea

An occasional loose stool isn't necessarily cause for alarm, but persistent or recurring diarrhea shouldn't be ignored.

Your pet's age, overall health, the severity of the diarrhea, and the presence of other symptoms all help determine how concerning it is.

If you're unsure whether your dog's or cat's diarrhea warrants a veterinary visit, give your veterinarian a call. It's always better to ask than to wait until a potentially treatable problem becomes more serious.