If your old dog has diarrhea and is not eating, it can be distressing and confusing. These symptoms may signal a temporary issue, or they could be the early signs of a serious health condition. In this article, we explore the most common causes of diarrhea and loss of appetite in senior dogs, what you can do at home, and when to seek veterinary care.
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Old Dog Diarrhea and Not Eating: Why it Happens
Old dog diarrhea and not eating often happens due to age-related health issues such as gastrointestinal disease, kidney or liver dysfunction, infections, or even cancer. As dogs age, their immune systems weaken, and their digestive systems become more sensitive, making them more prone to gastrointestinal upset.
Conditions like inflammatory bowel disease, pancreatitis, or organ failure can lead to both diarrhea and a loss of appetite. Additionally, dental pain, arthritis, or stress can further discourage an older dog from eating.
These symptoms should never be ignored, as they often signal an underlying medical condition that requires prompt veterinary attention.
Common Causes of Old Dog Diarrhea and Not Eating
Several health conditions can cause an old dog to have diarrhea and stop eating:
1. Gastrointestinal Infections
Bacterial, viral, or parasitic infections can cause diarrhea and poor appetite in senior dogs.
Older dogs may have weaker immune systems, making them more susceptible to infections from contaminated food, water, or environmental exposure.
Common culprits include:
Salmonella
E. coli
Giardia
Parvovirus (less common in seniors but still possible)
Infections can cause intestinal inflammation, which leads to loose stools and a reluctance to eat due to nausea or stomach pain.
Related: Dog Diarrhea and bloat (Explained)
2. Age-Related Organ Disease
One of the leading reasons for old dogs having diarrhea and not eating is underlying organ dysfunction.
As dogs age, organs such as the liver, kidneys, and pancreas can become less efficient.
Kidney disease can cause toxins to build up in the bloodstream, leading to appetite loss and gastrointestinal upset.
Liver disease affects digestion and nutrient absorption, often causing diarrhea and loss of appetite.
Pancreatitis, common in older dogs, leads to inflammation of the pancreas and results in vomiting, diarrhea, and refusal to eat.
These conditions are often progressive and need veterinary management to improve your dog’s quality of life.
3. Dietary Indiscretion or Food Intolerance
Even older dogs may get into the trash or eat spoiled food, causing an upset stomach.
Diarrhea in old dogs and not eating could be due to dietary indiscretion—eating something they shouldn’t have—or a new intolerance to ingredients in their food.
Food allergies or a sudden change in diet can disrupt the gut flora.
Older dogs are more sensitive to changes in diet, especially if they have a long history with a particular food.
If your senior dog has diarrhea and won’t eat, consider whether you’ve changed brands, added new treats, or given table scraps recently.
Related: Dog Diarrhea and stress (Explained)
4. Cancer or Tumors
Unfortunately, cancer is more common in senior dogs, and it can affect the gastrointestinal system, liver, or other internal organs.
Signs of cancer in dogs often include:
Chronic diarrhea
Vomiting
Refusal to eat
Weight loss
Lethargy
Intestinal tumors or cancerous growths can interfere with digestion and cause discomfort, leading to old dog diarrhea and appetite loss.
5. Side Effects of Medication
If your old dog is on long-term medication for arthritis, heart disease, or other chronic issues, the side effects may include diarrhea and not eating.
NSAIDs (non-steroidal anti-inflammatory drugs), antibiotics, and steroids can all irritate the gastrointestinal tract.
Over time, these side effects may cause persistent diarrhea or stomach upset.
If you suspect your old dog’s medication is causing diarrhea or appetite issues, consult your vet before making any changes.
6. Stress or Cognitive Dysfunction
Older dogs can experience increased anxiety or canine cognitive dysfunction (doggy dementia), especially as their routines or environments change.
Stress affects the digestive system and appetite. Common causes of stress in senior dogs include:
Moving to a new home
Changes in household members
Introduction of new pets
Loud noises (like thunderstorms or fireworks)
An old dog with diarrhea and not eating after a stressful event may recover once their environment stabilizes, but it’s important to rule out underlying health issues as well.
Risks of Diarrhea and Not Eating in Senior Dogs
In younger dogs, a day of not eating or a loose stool may not be concerning.
But in seniors, these symptoms can become serious very quickly.
An older dog with diarrhea who won’t eat is at a high risk of:
Dehydration: Especially dangerous in senior dogs with kidney issues.
Malnutrition: Loss of essential nutrients and weight can weaken their immune system.
Decline in organ function: Especially if the issue is prolonged.
Electrolyte imbalances: Which can affect heart and brain function.
What to Do if Your Old Dog Has Diarrhea and Is Not Eating
If your old dog has diarrhea and won’t eat, there are a few steps you can take at home—but only if your dog is still acting alert and hydrated.
1. Offer Bland Food
Temporarily feeding a bland diet may help soothe your senior dog’s stomach. Try:
Boiled chicken (no skin or seasoning)
Plain white rice
Boiled potatoes
Low-fat cottage cheese
Start with small portions and watch for improvement. If your old dog refuses food entirely, veterinary help is needed.
2. Ensure Hydration
A senior dog with diarrhea and no appetite is likely losing fluids. Make sure your dog has constant access to clean water. You can also:
Offer unflavored Pedialyte (check with your vet first)
Use a syringe to offer small amounts of water if they’re too weak to drink
3. Monitor Closely
Keep track of symptoms:
How many times a day is your dog passing stool?
What does the stool look like? (bloody, mucusy, very watery?)
How long has it been since they last ate?
The longer these symptoms persist, the more urgent veterinary care becomes.
When to See a Vet for Old Dog Diarrhea and Not Eating
While some cases resolve on their own, you should seek veterinary attention immediately if:
Diarrhea lasts more than 24–48 hours
There is blood or mucus in the stool
Your dog refuses food or water for more than a day
Your dog shows signs of pain, vomiting, or extreme lethargy
You suspect poisoning or ingestion of a foreign object
For senior dogs, even short-term symptoms can quickly become life-threatening.
Your vet may run bloodwork, fecal exams, x-rays, or ultrasounds to determine the underlying issue.
Preventing Diarrhea and Appetite Loss in Older Dogs
To reduce the chances of your old dog getting diarrhea and not eating, consider the following preventive tips:
Keep your dog on a consistent, high-quality senior diet
Avoid giving human food or fatty treats
Ensure your dog stays hydrated
Provide regular vet checkups to monitor for age-related conditions
Limit stress by maintaining a calm, predictable environment
Give medications as directed and report any side effects
Regular veterinary wellness visits are especially important for senior dogs.
These help catch problems early—before symptoms like diarrhea and appetite loss occur.
Key Takeaway: Old Dog Diarrhea and Not Eating
If your old dog has diarrhea and is not eating, don’t ignore it.
These symptoms may indicate digestive upset, illness, or a serious health condition that requires prompt attention.
Diarrhea and loss of appetite are especially dangerous in senior dogs due to their increased vulnerability to dehydration, weight loss, and other complications.
Always monitor your senior dog closely, provide supportive care, and contact your veterinarian if symptoms persist.
With early intervention and proper treatment, many older dogs can recover and return to enjoying their golden years comfortably.