A deficiency of red blood cells (RBC) is called anemia. It can be caused by the extreme loss of RBCs or their insufficient production. RBCs carry oxygen to the tissues so when not enough red blood cells circulate through the body, there is a lack of oxygen in the blood and tissues.

For a dog to be considered anemic, the red blood cells must either be disappearing or replaced slower than they should be. In the former case, it could be due to severe bleeding either from an obvious injury or possibly internal bleeding, such as from an ulcer in the digestive tract. Clotting disorders, such as those found with hemophilia and Von Willebrand disease, can also cause anemia.

The reason for slower replacement of red blood cells is usually due to issues in the bone marrow where RBC production occurs. Drug toxicity from certain drugs, such as acetaminophen, which in large doses, breaks up and damages RBCs, can affect the bone marrow. Chronic illnesses, such as kidney disease, along with certain cancers, severe hypothyroidism, and chemotherapy can also slow down the production of RBCs.

Other reasons why red blood cells may be being destroyed are heartworm disease, parasitic infections, such as whipworms, certain diseases carried by ticks, a heavy infestation of fleas, enzyme deficiencies, and immune-mediated hemolytic anemia, a condition where the dog’s immune system attacks its own red blood cells. It occurs most often in young to middle-aged dogs.

Signs of anemia can vary based on severity but generally includes loss of appetite, weight loss, lethargy, weakness, and sometimes vomiting and diarrhea.  Pale mucus membranes of the gums, which should normally be a nice pink, petechial or small hemorrhages under the skin, heart murmurs, and a rapid pulse may also be observed.

A complete exam and blood work will usually give a good answer to why a dog is anemic.  Further diagnostics, such as radiographs, may reveal more information. Treatment may vary, and depending on the cause of anemia, may include steroids. In severe cases, a blood transfusion may be recommended.