Dog Diarrhea: How Serious Is It and What Should You Do?

Diarrhea is the most common digestive complaint in dogs, and in most cases it is a short-lived problem that clears up on its own within a day or two. The difficult part for owners is knowing which case they are dealing with. A soft stool after a scavenged snack is ordinary. Bloody diarrhea in a puppy is a medical emergency, and the two can look similar from across the yard.

The useful questions are the same ones a vet will ask: how old is the dog, is the stool watery or just soft, is there blood, is the dog vomiting as well, and does the dog still look well.

What Usually Causes It

Diarrhea is a symptom with a long list of possible causes:

• Dietary upset — scavenging, a sudden food change, too many treats, or rich or fatty food
• Stress — boarding, moving house, a new pet in the home, or a dog show weekend
• Parasites — giardia, roundworms, hookworms, whipworms, coccidia
• Bacterial infection — Salmonella, Campylobacter, and Clostridium are common culprits
• Viral infection — parvovirus in unvaccinated dogs is the one that kills
• Foreign object or partial blockage — a swallowed toy, string, or bone fragment
• Toxins — many houseplants, human foods, and medications cause diarrhea
• Medications — antibiotics in particular disturb the gut's normal bacteria
• Underlying disease — pancreatitis, inflammatory bowel disease, kidney or liver disease, and intestinal tumors

Most acute cases in a healthy adult dog are dietary or stress-related. Chronic diarrhea, meaning more than a couple of weeks, almost always needs a workup rather than another round of bland food.

Judging the Severity

Stool appearance. Watery stool that comes in large volume and keeps going points to the small intestine. Frequent small amounts of mucus, sometimes with fresh blood, more often come from the colon. Fresh red blood usually means bleeding low in the gut, while black, tarry stool means blood has been digested higher up — that second one is the more urgent of the two.

How the dog looks. This matters more than the stool itself. A dog with diarrhea who is alert, drinking, and asking to go out is a very different patient from one who is quiet, refuses water, vomits, or stands with a hunched back.

Age and health. Puppies and senior dogs dehydrate quickly, and diarrhea can be their first sign of parvovirus or of a serious underlying illness. Dogs on steroids, chemotherapy, or with chronic conditions deserve an earlier call.

Duration. A day of soft stool after a scavenged meal is not the same as diarrhea that has been going on for a week, and it's not the same as diarrhea that started mild and is getting worse by the hour.

Deciding Whether to Monitor at Home

Watching at home is reasonable when every one of these is true:

• One or two loose stools, with normal energy and appetite
• No blood and no black tarry stool
• No vomiting, no bloating, no obvious pain
• The dog is drinking normally
• You know what was eaten, and it wasn't a toxin or an object
• The dog is an adult, vaccinated, and otherwise healthy

Checking hydration. Lift a fold of skin over the shoulders and let it go. It should snap back immediately. If it stays tented, or if the gums feel dry and tacky instead of slick, the dog is dehydrated and should be seen. This test is less reliable in very old or overweight dogs, so treat the gums and the dog's overall demeanor as the stronger signals.

What to feed. The old advice was to withhold food for 12 to 24 hours before reintroducing a bland diet. Many vets now skip the fast altogether, because the gut heals faster with small amounts of easily digested food, and because fasting a puppy is never a good idea. A practical middle path:

1. For a healthy adult dog, offer a small bland meal rather than a full bowl: plain boiled chicken or lean ground meat with white rice, or a prescription bland diet.
2. Feed three or four small meals that day instead of one or two large ones.
3. Keep fresh water available the whole time.
4. Add back the regular food gradually over two to three days once the stool has firmed up.
5. Skip the fatty extras, dairy, and any new treats until things settle.

Do not reach for human anti-diarrheal medication. Loperamide and similar drugs are not dosed for dogs, and some dogs — including many Collies and other herding breeds — can react badly to them. Plain cooked pumpkin or a spoonful of plain yogurt helps some dogs and does nothing for others; neither is a substitute for a vet visit if the symptoms are serious.

When to Call the Vet

Contact your vet the same day if you see any of the following:

• Blood in the stool, or black tarry stool
• Diarrhea together with vomiting
• Lethargy, weakness, or a dog who will not eat or drink
• Diarrhea in a puppy, a senior, or an unvaccinated dog
• More than 24 to 48 hours without improvement, or symptoms that are getting worse
• Abdominal pain, a swollen belly, or a dog who keeps looking at their stomach
• Suspected parvovirus: profuse bloody diarrhea, severe vomiting, and rapid deterioration
• Known or suspected access to a toxin, medication, or a swallowed object

Bring a photo of the stool if you can, along with your estimate of when it started and what the dog has eaten in the last couple of days. It saves time and often narrows the diagnosis.

What the Vet Will Do

For a straightforward case, expect a physical exam, questions about diet and exposure, and possibly a fecal test to look for parasites. If the picture is more complicated, blood work, x-rays, or an ultrasound may be needed to rule out a blockage, pancreatitis, or organ disease.

Treatment depends entirely on the cause: deworming for parasites, fluids and anti-nausea medication for a dog who is dehydrated, antibiotics in specific bacterial cases, a prescription diet for food-related problems, and surgery if something is stuck. Many simple cases need nothing more than supportive care and time.