What Are the Causes of Low White Blood Cell Count in Felines?

There are multiple types of white blood cells. Some white blood cells simply aren't present or are only present in low numbers in healthy feline patients. Other white blood cells are crucial and a decrease can indicate a problem. Leukopenia is the clinical term for an overall low white blood cell count and is seen with certain drugs, diseases or illnesses.

  1. Drugs

    • Some drugs can affect feline white blood cell counts. Corticosteroids used to control inflammation, anti-convulsants used to control seizures, and chemotherapy drugs used to fight cancer are leading causes of low white blood cell counts in felines. Estrogen can also cause an abnormally low white blood cell reading. Some wormers, blood pressure medications, antibiotics, anti-fungal drugs and thyroid medications can also lead to a decrease in white blood cell levels. Notify your veterinarian of any drugs your cat is taking, prescription or over the counter, prior to having blood work done.

    Infectious Diseases

    • The mere act of fighting off an infectious disease can leave cats with a low white blood cell count. Although white blood cell levels initially increase to fight off viral or bacterial infections, continued progress of an infectious disease can leave cats with decreased levels. Salmonellos is one infectious disease that causes low white blood cell counts from onset. Salmonellosis is caused by salmonella bacteria and is spread via contact with contaminated fecal matter.

    Illness

    • Non-communicable illnesses are sometimes responsible for a decrease in feline white blood cell counts. Cancer is one possible cause of a low white blood cell count and the drugs used to treat it are also known for this effect. Since all blood cells including white blood cells are made in bone marrow, diseases or disorders affecting the bone marrow can cause decreased white blood cell counts in felines. Bone marrow hypoplasia and bone marrow aplasia are two such disorders. Stress, such as the stress incurred by visiting the veterinarian, can cause a temporary decrease in white blood cell counts as the body activates its "fight or flight" response. The stress of a long-term non-communicable illness can also lead to a decrease in white blood cell levels. Autoimmune disorders and sepsis are also occasionally responsible for low white blood cell readings in felines.

    Feline Panleukopenia

    • Feline panleukopenia (FPV), also known as cat distemper or cat plague, is caused by a virus similar to the one that causes canine parvovirus. It is spread through contact with infected bodily fluids and contact with fleas. It can also be spread via fromites or inanimate objects in contact with an infected animal. FPV is able to spread between cats, ferrets and minks, but is non-transmissible to humans. Often deadly, feline panleukopenia attacks the lining of the stomach and intestines. Symptoms include lethargy, confusion depression, bloody diarrhea, vomiting, loss of appetite, decreased thirst and self-mutilation. Death often occurs via a secondary infection since FPV leaves the immune system depleted.