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Why is my senior dog losing weight, has diarrhea, and possible cancer?

Updated On September 23rd, 2025

Pet's info: Dog | Field Spaniel | Male | neutered | 13 years and 5 months old | 144 lbs

My 13 year old Field Spaniel is having issues with his pancreas. had blood work done and Dr feels its cancer, though he didn't feel any masses in his abdomen. I'm not sure. He is down about 10 pounds (over a year or so). Eats food but, not gaining weight. I have him on Pan-tenex (pancreatic enzymes). Not seeming to put weight on. He also takes Metronidazole to control diarrhea. I think it's pancreatitis. Don't know what else to do.

1 Answer

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on July 11th, 2017

I'm sorry Diesel isn't doing well! If he had pancreatitis, you would see symptoms such as repeated vomiting, vomiting undigested food, a hunched pain, a painful abdomen, a distended abdomen, diarrhea, loss of appetite, dehydration, and lethargy. Diesel would be extremely ill if he had pancreatitis, and from what you are describing, I would be inclined to think he doesn't have it. It is possible that he does have cancer even if your vet didn't feel any masses in his abdomen. There can still be tumors even if they can't be palpated, and cancer would cause him to eat and lose weight. Cancer can also cause diarrhea. Certain cancers also do not show any changes in blood work. I recommend having further testing done on him, such as x-rays or an ultrasound of his abdomen. These would help visualize if he has any tumors in his abdomen, and further testing such as a biopsy of them can be done if any are found. Unfortunately cancer is very common in senior dogs. I recommend having him seen by your vet again to discuss further testing. I hope this helps!

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