Anemia is defined as a deficiency or reduction in the normal number or concentration of red blood cells - called erythrocytes or “RBCs” that are circulating in a cat’s blood stream. As a general rule, adult cats are anemic when they have less than 5 million RBCs in 1 milliliter of blood or when the overall RBC percentage in their blood is less than 25%.
Causes of Feline Anemia
There are three general causes of anemia in cats: blood loss, destruction of RBCs and inadequate RBC production. The first two categories are called regenerative anemia; the last is considered non-regenerative.
- Blood loss reduces the number of circulating red blood cells because it decreases total blood volume. It can be caused by trauma, surgery, blood clotting abnormalities, ulcers, blood-sucking parasites (fleas, ticks, lice, hookworms), cancer and many other disorders or conditions.
- Destruction of RBCs (or an abnormally short RBC lifespan), also called hemolytic anemia, reduces the concentration of red blood cells in the bloodstream rather than total blood volume. Autoimmune hemolytic anemia is uncommon in cats but occasionally occurs when a cat’s immune system attacks its own red blood cells for no known reason. Non-immune-mediated hemolytic anemia happens when something else destroys a cat’s RBCs, such as parasites, hereditary diseases or exposure to toxins.
- Inadequate RBC production is the most common form of feline anemia. This serious condition often is attributable to some underlying disease such as feline leukemia, infectious peritonitis, bone marrow cancer, kidney failure, administration of certain drugs and enzyme abnormalities.
How Anemia Affects Cats and What Owners May See
Red blood cells carry oxygen from the lungs throughout the body. Normally, as they age or are damaged, RBCs break down and are either recycled to the bone marrow to be incorporated into new RBCs or processed and excreted by the liver. Anemic cats don’t have enough red blood cells to transport sufficient oxygen to their tissues and organs, which causes them to become oxygen-starved. Affected cats get weak, tired and lethargic. They develop exercise intolerance, elevated heart rate, bounding irregular pulses, pale mucous membranes, confusion, appetite loss, rapid breathing and ultimately collapse. Feeding a high-quality diet, preventing traumatic injuries, keeping current on vaccinations and following sound veterinarian-approved methods to keep parasites at bay can all help to reduce the occurrence of anemia in companion cats.
Diagnosis and Treatment
Veterinarians usually can diagnose anemia in cats by simple, fairly inexpensive routine blood tests that analyze the numbers and concentration of their circulating red blood cells. Sometimes, more advanced blood work and possibly bone marrow evaluation can be helpful to identify what is actually causing the cat’s anemia. Because the causes of feline anemia are so varied and often unrelated, it is really important to determine why a cat is anemic before deciding on and going down a treatment path.