Anemia can be caused by blood
loss or inadequate red blood cell production. In some cases, the body produces
red cells rapidly, but not fast enough to keep up with the losses. It may take
three to five days for the bone marrow to respond to a blood loss by producing
new red blood cells.
Rapid blood loss is caused by trauma and major hemorrhage. Shock will ensue.
Treatment of shock using intravenous electrolyte solutions and blood
transfusions is directed at controlling the bleeding and restoring fluid volume
and red blood cells.
Cats can get a variety of intestinal parasites, including some that are commonly referred to as “worms.” Infestations of intestinal worms can cause a variety of symptoms. Sometimes cats demonstrate few to no outward signs of infection, and the infestation can go undetected despite being a potentially serious health problem. Some feline parasitic worms are hazards for humane health as well.
A less obvious blood loss takes place through the gastrointestinal tract as
a result of hookworm or coccidia infestation, tumors, or ulceration. External parasites such as fleas and lice can cause a cat
to lose surprising amounts of blood.
Eighty percent of feline anemias are due to inadequate red blood cell
production. Iron, trace minerals, vitamins, and essential fatty acids are
incorporated into red blood cells, so a deficiency in building materials will
result in a failure to manufacture the final product.
Iron deficiency is a cause of anemia. Some cases are caused by diets low in
iron and other essential nutrients. However, most cases are caused by chronic
blood loss. Each milliliter of blood lost contains 0.5 mg of iron.
A number of diseases and toxic agents interfere with the production of red
blood cells in the bone marrow. They include feline leukemia and feline infectious
peritonitis, some cancers, drugs such as chloramphenicol, kidney failure with
uremia, and various chemicals and poisons. Kidney failure leads to a
deficiency of erythropoietin, a hormone that stimulates red blood cell
production in the bone marrow. In fact, any chronic illness can depress the
bone marrow and lead to anemia.
There are two known infectious agents that can cause anemia in cats.
Cytauxzoon felis is not very common and is passed to cats by ticks. Bobcats and
the Florida panther may be reservoirs of infection. Most cases occur in cats
living in rural, wooded areas of the Southeast. Depression, not eating, and a
fever may be noted in cats with this type of infection. Some will develop
jaundice. Cytauxzoonosis is usually fatal to domestic cats, and death occurs
rapidly. There is no standard treatment, but imidocarb dipropionate and
diminazene aceturate have been suggested as possible treatments if cases are
detected early on.
More common is infection with Mycoplasma haemophilus (formerly called
Hemobartonella felis). A variant is Mycoplasma haemominutum. This blood
parasite is primarily passed to cats through tick and flea bites, but it can
also be spread by cat bites and in utero or from infected queens to nursing
kittens. Red blood cells are destroyed by the cat’s own immune reactions to the
parasites. Mycoplasma haemophilus may also work in concert with feline leukemia
virus to stimulate bone marrow cancers.
Cats with this type of infectious anemia are often weak and may have fevers.
Some cats eat dirt or their litter in an attempt to add minerals to their diet.
If left untreated, up to 30 percent of affected cats may die.