Anemia in Cats

Anemia is the term veterinarians use to describe a reduction of red blood cells in the feline’s circulatory system. Red blood cells, known as erythrocytes, are equipped with a special iron containing molecule known as hemoglobin. This special molecule is what allows the red blood cells to pick up oxygen from the lungs and carry it to the body’s various organs. When the red blood cells are low in quantity, the feline begins developing symptoms related to a low oxygen supply, including difficulties in breathing. Anemia can be the result of disease, hormone abnormalities, bone marrow abnormalities, nutrition, or toxicity. 

Red blood cells carry oxygen and nutrients to the body, therefore a decreased level of these red blood cells cause clinical signs associated with these deficiencies including: 

• Exercise intolerance
• Lethargy 
• Decreased appetite 
• Pale mucous membranes (gums)
• Jaundice: yellowing of the mucus membranes and inside the ears
• Pica: craving and consumption of inappropriate elements 
• Tachycardia: increased heart rate 
• Tachypnoea: increased respiratory rate 
• Weakness

Types 

Anemia in cats is classified as either regenerative or non-regenerative. 

Regenerative Anemia 

In regenerative anemia, the feline’s bone marrow responds to the decreased level of circulating red blood cells by increasing erythrocyte production. Cases of red blood cell destruction and bleeding are usually classified as regenerative. 

Non-regenerative Anemia

In non-regenerative anemia, the feline’s bone marrow does not respond to the low level of red blood cells and does not produce new hemoglobin cells. Abnormalities of bone marrow and a decrease in the hormone that stimulates the production of erythrocytes are often classified as non-regenerative anemia. 

Causes of regenerative anemia include:

• Hypophosphatemia: blood phosphate deficiency common in diabetic cats. 
• Neonatal Isoerythrolysis: immunologic newborn cat disease. 
• Inherited red blood cell disorders (common in Somali and Abyssinian cat breeds)
• Infections (viruses, bacteria and other infectious organisms such as feline immunodeficiency virus and feline leukemia)
• Toxins, such as metals, chemicals, foods (e.g. onions, fava beans), plants 
• Human medications, such as acetaminophen and aspirin 

Causes of non-regenerative anemia include: 

• Myelofibrosis: disease that leads to enlargement of the liver and spleen.
• Myelodysplasia: disorder of the bone marrow 
• Primary Leukemia: a type of white blood cell cancer 
• Pure Cell Aplasia: severe reduction of red blood cells only linked to viral infection
• Aplastic Anemia: a disorder in which the bone marrow loses its ability to grow new blood cells. 
• Anemia of Chronic Disease: anemia is the result of a long-term inflammatory infection, hyperthyroidism, hormonal disorder or tumor. 
• Nutritional deficiencies (iron deficiency) 

Anemia in cats can be diagnosed through a review of your cat’s medical history, a physical exam, routine diagnostic tests, and through the consultation with the cat owner. The veterinarian will want to conduct a differential diagnosis on your cat to eliminate the possibility of ingestion of a toxic substance, infection, and organ failure, which commonly causes anemia. A urinalysis and blood work are likely tests to further diagnose a feline with suspected anemia.

CBC Complete Blood Cell Count

A complete blood cell count measures the levels of red blood cells, white blood cells and platelets, which provides important information to the veterinarian. 

PCV Packed Cell Volume or Hematocrit

Measures the percentage of blood volume occupied by erythrocytes, which provides important information regarding the blood’s ability to carry oxygen. 

Blood Smear

A blood smear is a test performed to identify blood cell abnormalities, revealing irregularities in size and shape. 

Bone Marrow Aspirate Biopsy

The act of using a fine needle to take bone marrow from inside the bones for observation. 

If the feline is in a severe stage of anemia, the veterinarian may request a blood transfusion to stabilize the cat before treating the underlying cause for the low red blood cell levels. The feline will need to have a blood test conducted before receiving the blood transfusion, as the incorrect blood type could result in adverse reactions. A donor or supply will be located, and infusions will take place while in hospital care. 

If the anemia is caused by an infection, toxic substance, organ failure, hormone deficiency, nutrient deficiency, or feline viral infection, the veterinarian will prescribe treatment based on the specific cause. 

Felines that have received blood transfusions may be hospitalized for a few days depending on the severity of the condition. Non-regenerative anemia feline cases will require continuous treatment and veterinary follow-up appointments to balance the number of circulating red blood cells, preventing a life-threatening anemic condition. Regenerative anemia cases will return to normal in most cases as soon as the underlying condition is addressed and treated.