Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

350 •DOG OWNER’S HOME VETERINARY HANDBOOK
Treatment: Treatment must be directed toward the cause of the anemia.
Gastrointestinal bleeding can be detected by checking the stools for microscopic
traces of blood. Urinalysis will pick up traces of blood in the urine that
may not be visible to the naked eye. Other tests can also be used to determine
the cause of the occult (microscopic) bleeding.
HEMOLYTIC ANEMIAS
Hemolysis is an acceleration in the normal process of red blood cell breakdown.
Red blood cells break down to form bile and hemoglobin. With severe
hemolysis, these breakdown products accumulate in the body. Accordingly, in
a dog experiencing an acute hemolytic crisis you would expect to see jaundice
and hemoglobinuria (passing dark-brown urine that contains hemoglobin). In
addition, the dog appears weak and pale and has a rapid pulse. The spleen,
liver, and lymph nodes may be enlarged.
Causes of hemolysis include immune-mediated hemolytic anemia, congenital
hemolytic anemia, infectious diseases (such as canine babesiosis and leptospirosis),
drug reactions to medications such as acetaminophen, and
poisonous snake bites. A number of bacteria produce toxins that destroy red
blood cells, so hemolysis can also occur with severe infections.
Neonatal isoerythrolysis is a hemolytic disease of newborn puppies; it is
discussed on page 503.
Immune-Mediated Hemolytic Anemia
This is the most common cause of hemolysis in adult dogs. Red blood cell
destruction is caused by auto-antibodies that attack antigens present on the
surface of the cells, or by antigens from medications or organisms attached to
the red blood cell walls. The weakened cells are trapped in the spleen and
destroyed.
Poodles, Old English Sheepdogs, Irish Setters, and Cocker Spaniels are
predisposed to immune-mediated hemolytic anemia, but all breeds are susceptible.
Affected dogs are usually between 2 and 8 years of age; females outnumber
males four to one.
Most cases of immune-mediated hemolytic anemia are idiopathic. That is,
the reason why the auto-antibodies developed in that particular dog is
unknown. In some cases there is a history of recent drug therapy. An immunemediated
hemolytic anemia also occurs with systemic lupus erythematosus.
The diagnosis is made by microscopic examination of blood smears, looking
for specific changes in the appearance of the erythrocytes and other blood
elements; and by serologic blood tests.
Treatment: Treatment of idiopathic immune-mediated hemolytic anemia
is directed toward preventing further red cell destruction by blocking the
antigen-antibody reaction using corticosteroids and immunosuppressants.