Friend, I am sorry Killa has been losing weight with swollen legs, I am sure this must worry you. In response to your question, when we see weight loss despite normal food intake this can be caused by many different medical conditions. It will be difficult for me to determine the exact underlying cause without a hands-on examination and some testing. But, common causes are absorption disorders in the intestinal tract, EPI (exocrine pancreatic insufficiency), kidney or liver disease, tumors, diabetes, etc. to name a few causes. The swelling in the back legs could be the result of accumulating fluid within the tissue (edema) as a result of low protein in the blood which can be caused by any of the above medical conditions. Or, he could have heart disease. The loose stool with blood is a sign of inflammation in the gastrointestinal which is likely secondary to any of the above-mentioned diseases.
As you can see from the above list, there are many possible causes. On history only it will not be possible to determine the exact underlying cause, I am sorry. Killa would need a hands-on examination by a veterinarian, blood work, urinalysis and x-rays as an initial screening test. Treatment will be based on examination and test results. If cost is a concern I would look into your local ASPCA or Shelter where they often offer veterinary services at a lower cost. In the meantime, start him on Pepcid AC (famotidine) 0.1-0.2 mg per pound body weight every 12 hours. You can buy pepcid ac over the counter in any pharmacy. Do Not give things like Pepto Bismol or Imodium. Change his diet to a bland diet of rice with boiled boneless chicken or ground beef.
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