Why is my dog losing weight?

Unexplained weight loss — where your dog is eating normally but still losing weight — is a significant symptom that always warrants a vet visit. A loss of more than 10% of body weight is considered clinically significant.

Most common causes

- Intestinal parasites — roundworms, hookworms, and whipworms steal nutrients. Often there are no obvious signs besides weight loss and a poor coat.
- Diabetes mellitus — dogs eat more but lose weight because they cannot use glucose properly. Also causes increased thirst and urination.
- Exocrine pancreatic insufficiency (EPI) — the pancreas fails to produce digestive enzymes. Dogs eat ravenously but cannot absorb nutrients; stools are pale, greasy, and very large.
- Inflammatory bowel disease (IBD) — chronic gut inflammation causes poor absorption. Often accompanied by intermittent vomiting and loose stools.
- Kidney or liver disease — both cause loss of appetite and muscle wasting over time.
- Cancer — unexplained weight loss in middle-aged to older dogs should always prompt cancer screening.
- Heart disease — cardiac cachexia is weight loss driven by the body's response to heart failure.
- Dental pain — a dog with a broken tooth or severe gum disease may eat less without showing obvious signs.

What your vet will do

Expect blood work (full panel including glucose, kidney values, liver enzymes), urinalysis, a fecal parasite test, and possibly abdominal ultrasound. This combination catches the vast majority of weight-loss causes.

Track it with Flovvi

Weigh your dog at home weekly using bathroom scales (weigh yourself, then weigh yourself holding the dog, subtract the difference). Log it in Flovvi so the trend is visible to your vet.