Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Older dogs often have more sensitive digestion, and ongoing vomiting, diarrhea, constipation, or weight loss in a senior dog is more likely to have an underlying cause, such as kidney or liver disease, pancreatitis, chronic enteropathy, dental pain, or cancer. Occasional mild upsets are common, but anything lasting more than a day or two, or recurring, deserves a vet visit.
Common causes in senior dogs
- Kidney or liver disease, which can cause nausea and vomiting
- Pancreatitis
- Chronic enteropathy or inflammatory bowel disease
- Intestinal tumors
- Dental disease making eating painful
- Medication side effects, such as NSAIDs
- Constipation from reduced activity, dehydration, or pain when posturing
Warning signs
- Weight loss
- Vomiting or diarrhea lasting more than a day or two, or recurring
- Black stool or blood
- Straining to defecate
- Reduced appetite
Supporting digestion
- Regular checkups with bloodwork every 6 months for seniors
- A complete, highly digestible diet your vet recommends
- Consistent meals and slow diet changes
- Fresh water and gentle daily exercise
- Fiber, if your vet advises it for constipation
What to avoid
- Fatty scraps
- Human anti-diarrhea or laxative medications without advice
- Assuming weight loss is normal aging
More: chronic digestive problems.
Sources
- AAHA Senior Care Guidelines for Dogs and Cats. 2023
- Merck Veterinary Manual: Vomiting and diarrhea in small animals
- Merck Veterinary Manual: Constipation in small animals
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.