Persian cat low white blood cells, not eating: Is vet treatment right?

This is only a CBC test result. The white count is low and it is mostly low from not enough lymphocytes. My suspicion would be a virus or cancer.

Viral infections are the most common cause of a low white blood cell count in cats. Feline Immunodeficiency Virus (FIV) and Feline Infectious Peritonitis (FIP) are two such viruses. These viruses invade the white blood cells and use them to make copies of themselves, increasing the virus’ strength and reducing the number of white blood cells.

Other possibilities include:

* Bacterial infections. These infections can range from abscesses to respiratory infections to sepsis. Essentially, any infection or inflammation causes a drop in white blood cells, particularly neutrophils. HER DROP IS LYMPHOCYTES, not neutrophils so I think this is less likely.

* Bone marrow diseases, or the panleukopenia virus, which destroys the marrow where white blood cells are produced.

* Pancreatitis. The inflammation of the pancreas will draw white blood cells from the bloodstream, lowering their count.

* Certain medications. Corticosteroids can actually suppress the production of white blood cells. THIS IS WHY I DON'T AGREE WITH THE STEROID ADMINISTRATION AT THIS TIME. Antibiotics, yes. Steroids, no. Just my opinion though. I can't really say your vet is wrong. This is just not what I would do especially since she is not responding.

More testing needs to be done:

* repeat the CBC to see where the white count is now
* chemistry panel to check liver, kidneys, etc
* FeLV/FIV testing
* FIP (corona virus) testing
* pancreatitis test

Hope this helps. Best wishes.