Why is my cat losing weight? Vet suggests dewormer, creatinine high?

The anemia could be from fleas but it could also be from chronic kidney disease. Are the BUN and PHOS also high or just the CREA? I think your vet needs to do some more testing to assess whether or not she is in kidney failure. An abdominal ultrasound, more specific blood testing and a urine test would be needed.

Poor Garfield! Tapeworms do not usually cause any significant weight loss or other symptoms in cats, so I would be very concerned that Garfield has a more serious problem. I would recommend taking him to the vet for an exam when you are able to. He/she can do some diagnostic testing (blood work and x-rays) if needed to help determine what's wrong, and will get him started on appropriate treatment depending on what is found.

The deworming pill and the symptoms you described have nothing to do with each other, if he is losing his fur and losing weight he is suffering from something serious. Sudden weight loss is always a very big warning light that should not be taken lightly, it's usually a sign of an internal disease that needs to be investigated, i strongly recommend taking him to the vet in order to get it checked, he will need to have a blood test done and possibly an xray as well in order to attempt to diagnose the reason for these symptoms.

Intestinal parasites can be picked up from the environment. If this is a tapeworm you saw (looks similar to a grain of rice), fleas can transmit tapeworm to cats. I would recommend treating Venus with a product called Profender, which will treat intestinal parasites including tapeworm. I would also consider using a flea and tick preventative such as Revolution or Frontline. I would also consider bringing a stool sample to a veterinarian to help diagnose what kind of intestinal parasites these could be. I hope this helps! Please let me know if you have any other questions or concerns and I would be more than happy to help you further.

Poor Rusty! Cats can have worms even if you don't see them in the feces. Oftentimes, there are eggs in the feces, but those can only be seen with a microscope. Sudden weight loss in cats can also be caused by diabetes, kidney disease, systemic illness, infection, or injury among other causes. I would have Rusty seen by a vet asap, and bring along a sample of his feces for the vet to examine. In addition to looking at his feces, the vet can do a physical exam, blood tests, and a urinalysis to diagnose what is causing his weight loss. Once the cause of the weight loss is diagnosed, the vet can discuss treatment options with you.

Cats that are losing protein through their kidneys can lose weight. With your cat's medical history, I would recommend having him examined by the vet. Blood work will check the kidneys and urinalysis will look for extra protein in the urine. The blood work can also screen for other issues that can cause weight loss.

Thanks for using Petco Pet Education Center, formerly Petcoach. I agree that a heavy worm burden can cause what you’re describing. In fact, it is the most likely reason. You can try an over the counter cat dewormer from a pet store. Follow the directions exactly in terms of amount and number of treatments. Hopefully, that’s all it takes to get her feeling better. Unfortunately, there are other (much less common) things that can cause large belly, weight loss, and lethargy including: FIP, heart failure, liver failure, cancer, protein problems, etc. So, if the dewormer doesn’t help, you may have to decide if you’d want to take her to the vet for further testing or if you’d like her humanely euthanized, etc. Best wishes and thank you so much for taking care of this stray!