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Why is my senior cat losing weight with diarrhea despite eating well?

Updated On September 23rd, 2025

Pet's info: Cat | Mixed Breed | Male | neutered | 10 years and 4 months old | 7 lbs

Male cat 10yrs old, last year lost half his body weight. Over last month gets bad bouts of very watery mustard yellow v. Smelly diarrhoea. Eats well doesn’t put weight on. Vets said he’d been tested for obvious pancreatic, thyroid and cancer. Any ideas?

2 Answers

Most Helpful Answer

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Answered By Daniel Fonza, DVM

Veterinarian

Published on November 1st, 2017

Hi there and thank you for using pet coach to address your concern. If your vet has done Baseline testing already then I would say an abdominal ultrasound should be considered as the next diagnostic test. I would want to check for things like lymphoma or another inflammatory intestinal disease. If your vet does not do ultrasounds than I would go see an internal medicine specialist to have this done. I hope this helps guide you in the right direction. Please feel free to contact me if any other questions or concerns that you may have.

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Other Answers

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    Answered By Jenny, DVM

    Veterinarian

    Published on February 28th, 2018

    At his age it can be a sign of cancer, inflammatory bowel disease or a high thyroid Your vet can check a stool sample to make sure there is not a bacterial infection also A simple blood test can check the thyroid as this will require a supplement every day to decrease that value An ultrasound can measure the thickness of the intestines. This can indicate inflammatory bowel vs cancer. This may result in a diet change to help along with medication You can always add a probiotic and vitamins to the diet to help withbthr stool until you can get seen

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