If your old dog has bloody diarrhea and vomiting, it can be an alarming experience for any dog owner.
While occasional digestive upset in senior dogs can happen, bloody diarrhea and vomiting in older dogs often point to something more serious.
We outline the common causes of this condition, why it’s more concerning in aging dogs, and what steps you should take to help your pet feel better.
Old Dog Bloody Diarrhea and Vomiting: Why It Happens
Old dog bloody diarrhea and vomiting typically occur due to serious gastrointestinal irritation, infections, organ dysfunction, or chronic diseases that are more common in aging pets.
As dogs get older, their immune systems weaken and their organs—like the liver, kidneys, and digestive tract—may not function as efficiently.
This makes them more vulnerable to conditions like gastrointestinal infections, pancreatitis, cancer, or medication side effects, all of which can cause internal bleeding and vomiting.
These symptoms are especially dangerous in senior dogs because they can lead to rapid dehydration and complications, requiring prompt veterinary attention.
Common Causes of Bloody Diarrhea and Vomiting in Older Dogs
1. Gastrointestinal Infections
One of the most common causes of bloody diarrhea and vomiting in older dogs is a bacterial, viral, or parasitic infection.
These can inflame the gut lining, leading to bleeding and vomiting.
Bacteria like Salmonella or E. coli can cause acute hemorrhagic gastroenteritis.
Viruses like parvovirus are less common in seniors but can still occur if vaccination status is incomplete.
Parasites like hookworms can also cause bloody stool and digestive upset, especially if the dog’s immune system is compromised.
In older dogs, even a mild infection can turn serious quickly due to slower immune responses.
Related: Old dog diarrhea and not eating (Here’s why)
2. Dietary Indiscretion and Toxins
Older dogs may accidentally consume spoiled food, garbage, or household toxins.
This behavior is called dietary indiscretion and often leads to vomiting and bloody diarrhea in old dogs.
Toxic substances, whether human medications or certain plants, can inflame the GI tract or damage internal organs, especially the kidneys or liver, which can lead to bleeding and severe gastrointestinal distress.
3. Chronic Illnesses
As dogs age, their organs start to decline in function. Chronic kidney disease or liver disease can affect how toxins are filtered out of the body.
When waste products build up, they can lead to nausea, vomiting, and gastrointestinal ulcers, which can cause bloody diarrhea.
Liver disease can reduce blood clotting ability, making any bleeding more serious.
Kidney disease can cause uremic gastritis, which may lead to vomiting blood or passing bloody stools.
4. Cancer
Unfortunately, cancer in older dogs is a common cause of vomiting and bloody diarrhea.
Tumors in the gastrointestinal tract can cause internal bleeding, irritation, and obstruction.
Gastrointestinal lymphoma, stomach cancer, or even metastatic cancers can all lead to these signs.
Signs that cancer may be involved include weight loss, reduced appetite, lethargy, and chronic vomiting.
Related: Old dog diarrhea and vomiting (Causes and when to seek care)
5. Pancreatitis
Pancreatitis, or inflammation of the pancreas, is common in older dogs and can lead to both vomiting and bloody diarrhea.
This condition often occurs after eating fatty foods and can range from mild to life-threatening.
Pancreatitis causes the pancreas to release digestive enzymes that attack the intestine and surrounding organs, resulting in gastrointestinal bleeding.
Older dogs with a history of digestive issues or who have previously experienced pancreatitis are more at risk.
6. Hemorrhagic Gastroenteritis (HGE)
HGE is an acute and severe condition where dogs suddenly vomit and pass bright red or tarry bloody stools.
Though the exact cause is unknown, it’s suspected to involve bacterial toxins, stress, or food reactions.
HGE can lead to shock in senior dogs if not treated quickly.
7. Medication Side Effects
Many senior dogs are on long-term medications for arthritis, heart disease, or other age-related conditions.
NSAIDs (non-steroidal anti-inflammatory drugs) and steroids are common culprits that can irritate the stomach lining, leading to ulcers and bleeding.
This is a common cause of vomiting blood or bloody diarrhea in old dogs.
If your dog starts vomiting or having blood in their stool shortly after starting a new medication, speak to your vet immediately.
8. Intestinal Blockage
Older dogs sometimes ingest foreign objects, like bones or toys, that can cause blockages in the gastrointestinal tract.
A blockage can cause food and fluids to back up, leading to vomiting and straining to defecate, often resulting in bloody diarrhea.
Blockages can also occur from internal causes like tumors or hernias. These require urgent surgical intervention.
Symptoms to Watch For Beyond Bloody Diarrhea and Vomiting
If your senior dog has bloody diarrhea and is vomiting, also watch for the following signs, which may indicate worsening health:
Lethargy or unresponsiveness
Pale or gray gums
Loss of appetite
Collapse or weakness
Rapid heart rate or shallow breathing
Abdominal bloating or pain
Weight loss
The presence of these symptoms means it’s not just a minor issue — it’s a medical emergency.
What to Do If Your Old Dog Has Bloody Diarrhea and Vomiting
When your old dog has bloody diarrhea and vomiting, it’s essential to act quickly. Here’s what you can do:
1. Call Your Veterinarian Immediately
Don’t wait. Old dog bloody diarrhea and vomiting can cause dehydration and electrolyte imbalances quickly.
Your vet may need to perform:
Blood tests
Fecal analysis
Ultrasounds or X-rays
Endoscopy
IV fluid therapy
Anti-nausea or antibiotic medication
Early treatment improves your dog’s chances of recovery dramatically.
2. Withhold Food for 12–24 Hours (Only if Vet Advises)
Sometimes, giving your dog’s stomach a rest helps reduce irritation. But never withhold water.
Hydration is critical. Always consult your vet before doing this, especially for older dogs, who can decline quickly.
3. Monitor Fluid Intake
If your dog refuses to drink, shows signs of dehydration (dry gums, sunken eyes, skin tenting), or vomits water, seek emergency care.
Dehydration in senior dogs can become fatal very fast.
4. Keep Your Dog Calm and Comfortable
Reduce stress by keeping your dog in a quiet, familiar space.
Offer blankets, limit movement, and avoid excitement. Stress can worsen gastrointestinal symptoms.
5. Check Medications
If your dog is on medication, do not give another dose until your vet says it’s safe.
NSAIDs, antibiotics, or steroids might need to be paused or replaced.
6. Bring a Stool Sample to the Vet
If possible, collect a fresh stool sample for your vet to analyze.
This can help identify parasites, bacteria, or blood presence.
When to Seek Emergency Vet Care
Take your old dog to an emergency vet immediately if they show:
Repeated vomiting or vomiting blood
Continuous bloody diarrhea
Signs of collapse or shock
No interest in drinking water
Labored breathing or rapid heartbeat
Pale gums or black, tarry stools
Seizures or disorientation
Older dogs have lower reserves to deal with rapid fluid loss, making swift action crucial.
Key Takeaway
While an upset stomach may not seem like a big deal in younger dogs, bloody diarrhea and vomiting in old dogs is a serious red flag.
It could be anything from infection to cancer to poisoning. The key is acting quickly and knowing the symptoms that require emergency care.
If your old dog is vomiting and passing bloody diarrhea, contact your veterinarian without delay.
With timely care, many underlying causes can be managed or treated effectively — helping your beloved senior dog feel better and stay healthy.