Treating a Low White Blood Cell Count in Cats Identifying and Treating This Condition

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You never want your cat to have a low white blood count because it leaves them vulnerable to serious infections. Learn all about how a low white blood cell count can affect your cat's health, and what can be done.

“Leukopenia” is a decrease in the number of total white blood cells found in blood, which for your cat can be rather bad news. After all, white blood cells comprise the defense team that protects against common illnesses and serious infections.

So what causes a low white blood cell count in cats? First it helps to understand the makeup of white blood cells, also known as leukocytes, and their functions:

  • Neutrophils and Eosinophils are released into the bloodstream to destroy bacteria.
  • Lymphocytes are produced in the lymph nodes and spleen.
  • Monocytes are stored in the spleen and bone marrow.
  • Researchers aren’t entirely clear as to the main purpose of basophils.

A normal white blood cell count in cats typically ranges from 5,500 to 19,500 per microliter of blood. To determine your cat’s count the vet will run a complete blood count. Low levels of neutrophils and lymphocytes circulating the blood indicate that these cells are at the site of an infection, or that sepsis has occurred. This drop is typically temporary, with counts rising to normal in a few days.

Why a Cat Would Have a Low White Blood Cell Count

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 causes 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.
  • 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, which are used to treat arthritis can actually suppress the production of white blood cells.
  • Stress. As a response to stress the cat’s immune system may begin to repress itself, resulting in a decreased production of white blood cells.

How Will I Know if My Cat is Sick?

Symptoms are typically related to the cause of the high white blood cell count.

  • If the cause is a viral infection such as Feline Immunodeficiency Virus, symptoms will appear as fever, moodiness, swollen lymph nodes, lack of appetite, fatigue, inflammation of the gums, nasal and eye discharge, vomiting, bloody diarrhea, and hair loss. Feline Infectious Peritonitis symptoms include those of Feline Immunodeficiency Virus, as well as fluid buildup in the lungs, difficulty breathing, distended abdomen, frequent urination, and  jaundice.
  • If the cause is a bacterial infection, symptoms will appear as fever, lack of appetite, moodiness, and fatigue. If the infection is external, there may be a rash, wound, or abscess. If the infection is internal, additional symptoms could include swollen lymph nodes, muscle and joint pain and stiffness, vomiting, and diarrhea.
  • If the cause is a bone marrow disease such as panleukopenia, symptoms will be fever, lack of appetite, vomiting, diarrhea, and fatigue.
  • If the cause is pancreatitis, symptoms will appear as trouble breathing, fatigue, lack of appetite, and  lower than normal body temperature. Unlike dogs, cats typically do not vomit or exhibit abdominal pain.
  • If the cause is a medication, the symptoms can vary. Your cat could exhibit anything from fever and moodiness to lack of appetite and diarrhea, which is why it’s best to discuss every new medication with your vet.
  • If the cause is stress, symptoms will likely appear as aggression, decreased social interaction, lack of appetite, and hair loss.

Getting Your Cat’s White Blood Cell Count Back Up

If your cat’s white blood cell levels are low, your vet will recommend a treatment based on the cause of the issue.

  • There are unfortunately no medications that can combat viruses. When it comes to a viral infection like Feline Immunodeficiency Virus or Feline Infectious Peritonitis, the main focus is supportive care, such as increasing fluids, devising a nutrient-rich diet, and administering antibiotics to prevent and treat secondary infections that may occur. Unfortunately, most cases of FIP lead to death, but there are reliable vaccines to prevent such viruses from taking hold.
  • Bacterial infections can be treated with a variety of medications, particularly antibiotics.
  • Bone marrow disease is incurable and care will be supportive. In severe cases, blood transfusions may be necessary. However, there is a reliable vaccine to prevent the condition.
  • Hospitalization may be recommended for cats suffering from pancreatitis. During your cat’s stay, fluids and pain and anti-inflammatory medications will be administered.

It is import that you stay up to date with your cat’s wellness visits, in which your vet will run routine blood cell counts in an effort to spot any underlying health issues.

Knowing the aftereffects of such conditions can be especially beneficial for you as a pet parent. It doesn't only help you to put the correct practices in place but also take care of the appropriate measures to maintain their health.

Feline Anemia Causes

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You are probably familiar with anemia because it is a fairly common condition in humans. But did you know that cats can suffer from it too? Feline anemia develops when there are not enough red blood cells in the body to deliver the adequate amount of oxygen to the tissues. This is either because the body is not producing enough red blood cells, or because the red blood cell count is lowered through blood loss or blood cell destruction. Either way, these irregularities and the resulting anemia are typically caused by underlying medical conditions. Let’s take a look at the causes.

Types of Feline Anemia

There are two types of feline anemia -- nonregenerative and regenerative.

Nonregenerative anemia is the result of insufficient production of red blood cells by the bone marrow. In many cases, an underlying medical condition displaces or eliminates the red blood cells, and the bone marrow cannot keep up with the heavy demand for new cells.

Regenerative anemia is either the result of blood loss or hemolysis, which is the atypical destruction of red blood cells. Immune-mediated hemolytic anemia (or IMHA) -- a form of regenerative anemia -- occurs when a cat’s body is tricked into seeing red blood cells as foreign, and the immune system kicks into action to destroy them.

Nonregenerative Anemia Causes

Conditions that can cause inadequate red blood cell production are:

Regenerative Anemia Causes

Conditions that can result in blood loss are:

  • Injury or trauma -- either external or internal
  • Intestinal, kidney, or bladder tumors
  • Clotting conditions
  • Severe parasitic infections from ticks and fleas, such as Cytauxzoon felis and Mycoplasma haemophilus. Cytauxzoon felis is an often fatal infection passed to cats by ticks, usually in rural areas. Mycoplasma haemophilus is a parasite passed to cats through tick and flea bites. It can also be passed through cat bites or from an infected mother cat while the kitten is in utero.

Conditions that can result in red blood cell destruction (hemolysis):

Is Anemia Hereditary?

Anemia itself is not hereditary, and all cats are at equal risk for developing it. However, there are some rare genetic disorders -- such as neonatal isoerythrolysis and the blood disorder porphyria -- that can cause anemia. Your veterinarian may check your cat for these and other genetic disorders if they discover that your cat has anemia.

See Your Veterinarian

If your cat is suffering from any of the above conditions, or if you notice symptoms of anemia, contact your veterinarian. They will perform a series of tests to determine if your cat is suffering from a low red blood cell count. If so, there are a number of treatment options available, and for many cats the recovery prognosis is very good. 

Symptoms of Anemia in Cats

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Anemia -- a condition which means there are not enough red blood cells in the body to deliver sufficient oxygen to the tissues -- can affect any cat at any age. The symptoms can either be mild or severe depending on your cat’s degree of illness, and unfortunately, many of the symptoms of anemia mimic those of other health conditions, so it can sometimes be difficult to spot.

However, knowing the classic symptoms of anemia in cats can help you to begin putting the pieces together, especially if you already know that your cat is suffering from one of the underlying conditions that can cause anemia.

Common Anemia Symptoms in Cats

Not all cats with anemia will exhibit the same symptoms, and the severity of your cat’s symptoms will depend on just how sick they are. Here are some of the most common symptoms of anemia in cats.

  • Lethargy and Weakness: Because oxygen is required for normal bodily functions and anemia reduces the amount of oxygen delivered to body tissues, it can result in lethargy and weakness. You may see your cat sleeping a lot and looking frail, and they may not be interested in regular activities like playing or exploring.
  • Lack of Appetite and Weight Loss: When a cat is sick, their appetite is often the first thing to go. Because they are not eating normally, they may also lose weight. These serious symptoms are seen with many health conditions, and they should never be ignored.
  • White or Pale Gums or Tongue: These are perhaps the most obvious symptoms of anemia. These mucus membranes often turn white or pale because the oxygen that gives those tissues their healthy red or bright pink color is not being delivered in adequate amounts. Your cat’s nose or the bottom of their eyelids may also appear pale.
  • Rapid Breathing and Increased Pulse: In severe cases of anemia, if the cat’s body is going into shock, you may see rapid breathing or an increased heart rate. These are also common symptoms of heart disease and sometimes the conditions are confused.
  • Eating Dirt or Litter: Some cats with anemia develop an iron deficiency. It is somewhat rare and typically only seen in cats on very poor diets or those who are experiencing severe blood loss. Cats who have an irony deficiency may attempt to eat dirt or litter to ingest the iron that their body is telling them they need.
  • Fever: Cats suffering from anemia caused by a parasitic infection may develop a fever.

In mild cases of anemia, a cat may show no symptoms, and the condition will only be discovered through blood testing.

When To Seek Help

Any of the above symptoms -- especially if there is no other explanation -- warrant a trip to the veterinarian. Your vet will run a series of tests to determine if your cat is suffering from anemia, and if they are, will suggest treatment options. Many cats respond very well to anemia treatments, and the sooner you can get started, the better off your cat will be.

Frequently Asked Questions

What does low white blood cells mean in cats?

Low white blood cell count in cats is a condition that can be caused by a number of things. One common cause is feline leukemia. This disease causes the immune system to be weakened, which leads to a low white blood cell count. Another common cause is an infection of some kind. This can range from something simple like an abscessed tooth or a cold to something more serious like an untreated urinary tract infection or even pneumonia. Other causes include autoimmune diseases like feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), or feline AIDS; inflammatory diseases like arthritis; and cancers affecting the lymphatic system. If your cat has low white blood cells, you should schedule a visit with your vet as soon as possible so they can diagnose what is causing the problem and give you advice on how to treat it.

What causes low blood count in cats?

There are a few different issues that can cause low blood counts in cats. For example, some cats have anemia, which is a condition where their red blood cells don't carry enough oxygen to the rest of their body. This can be caused by parasites, bacteria, or viruses. Feline Panleukopenia is a condition that causes severe anemia in cats. It can be fatal, so it's important to get your cat treated right away if you suspect they have it. The virus targets the red blood cells, which carry oxygen throughout the body. It attacks the red blood cells in the bone marrow, preventing them from being able to produce new red blood cells. That's why cats with feline panleukopenia often have low numbers of platelets as well: platelets help clot blood when it's injured or damaged, but they can't do their job when there aren't enough mature red blood cells around. Another example is when your cat's immune system attacks its own red blood cells. This happens when your cat has feline leukemia virus (FeLV), which is a virus that can be passed from cat to cat through saliva and skin contact. If you notice that your cat isn't eating much or seems to have lost interest in other activities they normally enjoy, it could mean they have FeLV or another disease like it.

Is low white blood count serious?

Yes, low white blood cell count in cats can be serious. The white blood cells are what your cat's body uses to fight off infections, so if you see a low white blood cell count, it means your cat is not fighting off infections as well as it should. Low white blood cell counts could lead to severe and life-threatening illnesses like pneumonia or sepsis. There are lots of reasons why a cat may have low white blood cell counts, including exposure to a virus or bacteria, injury or trauma to the body, certain medications, and more. If your cat has low white blood cell counts and isn't getting better after a few days of antibiotics or other treatment, talk with your vet about other options for treatment.

Can white blood cells be low for no reason?

Yes, white blood cells can be low in cats for no reason. If your cat has no symptoms of illness and has normal red blood cell counts and platelet counts but still has a low white blood cell count, it's possible that it has neutrophil reduction syndrome (NRDS). This can be caused by an unknown cause or by environmental factors such as exposure to certain medications or vaccines. It's important to talk with your veterinarian about what you're seeing and feeling in your cat. The vet may recommend additional tests to help diagnose the problem and determine the best course of action.

What are the symptoms of low white blood cells?

The most common symptom of low white blood cells in cats is a fever. In addition, if the cat has a bacterial infection, which is more likely to occur if its white blood cells are low, it may experience diarrhea and vomiting. If your cat's white blood cells are low because of a viral infection, it may have an enlarged spleen or liver.
More on Cat Health

Why Is My Pet Coughing?
The Truth About Toxoplasmosis in Cats
5 Ways to Prevent Feline Cystitis

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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