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There are many different ways that you can notice this disease when it begins to affect your pet. The most common sign is lethargy. Your pet will simply not have as much energy as it normally does. This is a sign that can be found in many diseases.  However, if you happen to look at your pet's gums, you may also notice that they are pale or, less commonly, have a yellow appearance. These signs are also found in many diseases, but this may be immune-mediated hemolytic anemia (IMHA).
           
Blood is made up of water, molecules, a few white blood cells (cells of the immune system), and a lot of red blood cells (RBCs). Red blood cells are responsible for carrying oxygen from the lungs to all of the cells and organs of the body. When RBCs are carrying oxygen to organs in arteries, they are a bright red color. On the other hand, once the oxygen is delivered to the organs, it returns to the lungs in veins. Veins are blue because the RBCs are not carrying much oxygen. Gums are pale in IMHA because there are fewer RBCs in the blood, and therefore, the blood has less colour.
           
IMHA is a type of hemolytic anemia. Anemia is a condition where there aren’t enough RBCs in blood. An animal with anemia will look pale and will have very little energy. It will be tired because fewer RBCs mean that there is less oxygen getting to the body’s cells. Cells cannot function properly without oxygen, which means the body has less energy.
           
Anemia can have a few different causes. Some types of anemia are caused because the bone marrow is not functioning properly and doesn’t produce enough RBCs. Blood loss (for example, due to injury) also causes anemia. Other types of anemia are caused because something is killing the RBCs. This type of anemia is called ‘hemolytic anemia’. Many different substances can kill RBCs, such as toxins and infections. In immune-mediated hemolytic anemia, the RBCs are not being killed by something outside of the body. In IMHA, the body is killing its own RBCs. Sometimes something can happen that tricks the body’s immune system into thinking that the RBCs are invaders. This can happen after an infection, due to a drug, or because of molecules produced by cancer. Most of the time, we never know why the body begins to kill its own RBCs.
           
As we mentioned at the beginning, the most common signs in an animal with IMHA are lethargy and possibly pale gums.
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