Anemia is a low red blood cell count and can be a life-threatening condition. Tissues that do not receive enough oxygen and nutrition cannot function properly. There are many causes of anemia. It can result from excessive bleeding and losing a large amount of blood. It can occur if an animal is flea-infested and is drained of blood by the parasites. Anemia can also result from poor nutrition or long-term disease. It can occur when drugs or cancer suppress the bone marrow, which contains the immature blood cells. A red blood cell parasite called Hemobartonella can affect cats. This organism enters red blood cells and causes them to destruct within the cat's body. Regional parasites can also cause anemia.

The treatments for anemia are aimed at the specific causes. A blood transfusion acts as a temporary fix until the animal's body can regenerate enough replacement cells. Cats have two major blood types, A and B. In North America 98 percent of all cats have type A blood. Type B blood is most often seen in certain purebred cats including the British Shorthair, Devon Rex, Cornish Rex, Abyssinian and Somali.