It’s always worrisome when your dog isn’t feeling well—but when your old dog has diarrhea and is shaking, it can feel even more alarming.
These symptoms together can point to a wide range of issues, some of which may be age-related and serious.
We outline the common causes of diarrhea and shaking in older dogs, what these symptoms might mean for your senior pet, and when it’s time to call the vet.
Here's Why Old Dog Diarrhea and Shaking Happens
Diarrhea and shaking in senior dogs are not diseases themselves, but warning signs of underlying health problems. These could include age-related illnesses, dietary issues, infections, or more severe systemic conditions.
In older dogs especially, these symptoms are more likely to be complicated by chronic health conditions, a weakened immune system, and slower recovery time.
When these two symptoms occur together in a senior dog, it’s important to investigate promptly. Here’s why:
Diarrhea leads to rapid fluid loss and can cause dehydration.
Shaking or tremors may signal pain, nausea, weakness, or even neurological issues.
In elderly dogs, the tolerance for illness is reduced, and what may seem mild can escalate quickly.
What Shaking Looks Like in Older Dogs
Shaking, tremors, or trembling in senior dogs can appear in different forms. It can range from subtle muscle twitches to full-body shivering.
Common signs include:
Muscle spasms or trembling of the entire body
Shaking in the limbs even when resting
Visible weakness or instability when walking
Increased panting or anxiety while trying to move
Shaking that worsens at night or after exertion
Difficulty standing or navigating stairs
Constant twitching while sleeping (beyond typical dreaming)
In older dogs, arthritis, joint pain, and muscle weakness can worsen these symptoms.
Additionally, underlying neurologic disorders like canine cognitive dysfunction (doggy dementia) may cause disorientation and tremors.
Related: Dog diarrhea and shaking (Explained)
What Diarrhea Looks Like in Older Dogs
Diarrhea in older dogs often appears as frequent, watery, or loose stools. Sometimes it may be accompanied by other digestive signs.
Additional symptoms may include:
Loss of appetite
Vomiting or dry heaving
Drooling or excessive licking of lips (nausea)
Abdominal bloating or discomfort
Lethargy or unusual tiredness
Signs of dehydration (dry gums, sunken eyes, skin tenting)
Blood or mucus in the stool
Weight loss if diarrhea persists
Low body temperature or fever
Older dogs can dehydrate faster and may already be managing chronic conditions like kidney disease, which makes diarrhea more dangerous.
Can an Upset Stomach Cause Shaking in Older Dogs?
Yes. An upset stomach in an older dog can definitely lead to shaking. Digestive distress can trigger the body’s stress response, especially in seniors.
The discomfort of nausea, cramping, or bloating may cause tremors or restlessness.
Additionally:
Senior dogs may shake from pain, especially if they have arthritis or abdominal discomfort.
If the stomach upset is due to pancreatitis, a condition more common in older dogs, shaking and diarrhea are typical.
Shaking can also be due to weakness caused by low blood sugar or dehydration, both of which are more serious in senior dogs.
Common Causes of Diarrhea and Shaking in Older Dogs
In senior dogs, several specific conditions may trigger both diarrhea and shaking. Below are the most common causes:
1. Age-Related Illnesses
Kidney failure
Liver disease
Pancreatitis
Canine cognitive dysfunction (dog dementia)
Cancer
These diseases may cause systemic inflammation, affect digestion, and lead to muscle tremors, diarrhea, and general weakness.
Related: Dog diarrhea and not eating (Explained)
2. Pain or Discomfort
Chronic pain from arthritis, spinal issues, or abdominal problems can cause dogs to shake.
When combined with an upset stomach or digestive illness, the shaking is often more pronounced.
3. Dietary Indiscretion or Sudden Diet Changes
Senior dogs are often more sensitive to food changes.
Eating table scraps, spoiled food, or unfamiliar treats can cause gastrointestinal upset, diarrhea, and a stress response leading to shaking.
4. Toxin Exposure
Old dogs may accidentally ingest toxins such as:
Human medications
Household chemicals
Toxic plants or moldy food
These can lead to violent shaking, vomiting, diarrhea, and even seizures.
5. Infections
Older dogs have weaker immune systems. They may be more vulnerable to:
Viral infections (e.g., parvovirus, though less common in vaccinated seniors)
Bacterial infections
Intestinal parasites such as hookworms or giardia
Infections can cause fever, diarrhea, and muscle tremors.
6. Medication Side Effects
Senior dogs often take medications for arthritis, heart disease, or other chronic issues.
Some drugs can irritate the stomach or have neurological side effects.
Watch for shaking or diarrhea after a medication change or dosage adjustment.
7. Stress and Anxiety
Older dogs may become more sensitive to changes in routine or environment.
Stress can cause tummy troubles and shivering, especially in dogs with cognitive decline.
What To Do If Your Senior Dog Has Diarrhea and Shaking
If your older dog is experiencing both diarrhea and shaking, here’s what you should do:
1. Assess Severity
Is the diarrhea persistent or bloody?
Is your dog lethargic, vomiting, or unable to stand?
Is the shaking constant or worsening?
If multiple symptoms are present, or your dog seems weak or in pain, seek veterinary help immediately.
2. Keep Your Dog Hydrated
Offer small amounts of water or electrolyte solutions (like unflavored Pedialyte). Dehydration can occur quickly in seniors.
3. Provide a Bland Diet (if your vet approves)
If symptoms are mild and your vet gives the go-ahead, feed:
Boiled chicken and white rice
Plain pumpkin puree (not pie filling)
Prescription gastrointestinal diets for older dogs
Avoid fatty foods, treats, or table scraps.
4. Keep Your Dog Comfortable
Warm bedding, quiet rest, and limited physical activity can help reduce stress and shaking.
When to See a Vet Immediately
Call your vet as soon as possible if your senior dog:
Has bloody or black stools
Shows signs of severe pain (yelping, stiff posture, panting)
Is unresponsive, disoriented, or collapses
Has persistent vomiting along with diarrhea
Shows signs of confusion, head pressing, or seizures
Is experiencing prolonged shaking or tremors
For older dogs, early intervention is crucial.
Their aging bodies don’t compensate for illness the way younger dogs can.
Key Takeaway
Diarrhea and shaking in older dogs shouldn’t be taken lightly. While it could be as simple as a mild stomach upset, it could also be a sign of something far more serious—especially in aging pets with underlying conditions.
Be observant, keep your senior dog hydrated, and consult your vet to get to the root of the problem.
When it comes to older dogs, acting quickly can make a huge difference in recovery and quality of life.