Answer: Three main causes of anemia are recognized. One is the severe loss of cells due to bleeding (hemorrhagic anemia) which can occur suddenly if a major blood vessel is severed. Loss obviously, a slow but persistent loss of blood can produce this type of anemia, e.g. from a heavy infestation with blood-sucking parasites such as fleas, or from poisoning with the anti-coagulant rat poison warfarin which both damages the blood vessels and prevent the escaping blood from clotting.
Hemolytic anemia arises from the destruction of red blood cells within the circulation. This can be caused by the blood parasite Haemobartonnella felis or by bacterial toxins, or by such poisons as lead, phenol and chlorate and the drugs phenacetin and sulphafurazole.
Finally, anemia may be due to a failure or the red bone marrow contained within certain beans to produce the sufficient replacement cells to keep pace with natural losses. Because each red blood cell survives for about ten to eleven weeks it can take a long time for this defective production to result in discernible anemia. It can develop if the cat is deprived of adequate amounts of the few materials necessary for the production of red blood cells such as iron, protein, and vitamin B.
Damage to the bone marrow can also be responsible for hypo plastic anemia, rarely this is due to bone marrow tumors or excessive doses of radiation. In the cat most likely cause of bone marrow damage is drugs. Cats have greater difficulty then many other species in detoxicating many drugs i.e. breaking them down in the liver to harmless substance which can be excreted. They are therefore particularly at risk from any toxic side-effects which a drug may possess. Drugs known to damage the bone marrow in the cat include the antibiotic chloramphenicol, insecticides and aspirin. In fact, aspirin has two effects which in combination produce anemia very rapidly. It cause ulceration and hemorrhages in various organs, particularly the intestines, and because of the effect on the bone marrow the blood cells that are lost cannot be effectively replaced. Aspirin also has toxic effects on the liver and is extremely harmful to cats. A daily does of half a 300 mg tablet will kill most cats in two to three weeks.
