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Anemia in Dogs and Cats
Kristi S. Lively, DVM, DABVP
BASIC INFORMATION
Description
Anemia is an abnormally low red blood cell (RBC) count. The primary function of
the RBC is to transport oxygen to tissues, so inadequate RBC numbers cause
decreased oxygenation of tissues. Anemia is not a specific disease but reflects
an underlying disease process.
Causes
Anemia may be caused by decreased production of RBCs, increased destruction of
RBCs (hemolysis), or loss of RBCs. Decreased RBC production arises secondary to
chronic metabolic diseases, such as kidney disease, cancer, or malnutrition.
RBCs are produced in the bone marrow, and infections or cancer of the marrow
may also affect production. Excessive RBC destruction is commonly immune
mediated, although toxins, infections, blood parasites, cancer, drug reactions,
and inherited RBC membrane defects can also cause hemolysis. Anemia secondary
to blood loss may be overtly noted with trauma, but it may be hidden with other
conditions, such as gastrointestinal tract bleeding, certain parasites (fleas,
ticks, hookworms), and clotting disorders.
· Evaluation of a blood smear to identify potential blood parasites ·
Biochemistry profile and urinalysis to evaluate organ function · Fecal
examination to identify internal parasites · Reticulocyte count to determine
whether the bone marrow is trying to replace lost RBCs · Bone marrow aspiration
and evaluation if there is no evidence that the RBCs are regenerating (low
reticulocyte count) · X-rays to evaluate for the presence of tumors, size of
various organs, or evidence of trauma · Clotting tests if excessive or
persistent bleeding is present · Other tests to screen for potential
immune-mediated destruction of RBCs
TREATMENT AND FOLLOW-UP
Treatment Options
If the anemia is severe and life-threatening, hospitalization and blood
transfusions may be recommended to stabilize the patient while the underlying
disease is identified and potentially treated. Patients with severe anemia may
also require oxygen therapy to compensate for decreased oxygen delivery to
tissues. The treatment plan is then directed at the underlying cause and may
include immunosuppressive drugs, antibiotics, parasite control, chemotherapy,
or hormone injections. Not all underlying causes of anemia are treatable.
Clinical Signs
Clinical signs of anemia depend on both the severity of the anemia and the
underlying cause. Clinical anemia typically causes weakness, lethargy,
increased heart rate, poor appetite, and pale gums. Signs of the underlying
cause may include fever, jaundice, enlarged spleen, pica (eating abnormal
objects such as dirt), enlarged lymph nodes (glands), vomiting, diarrhea,
weight loss, or depression.
Follow-up Care
Follow-up depends on the underlying cause. Isolated events such as trauma may
require monitoring of the PCV for a few days, whereas chronic conditions such
as cancer or renal disease may require long-term monitoring. Immune-mediated
anemia usually requires several months of therapy and monitoring.
Diagnostic Tests
Anemia is reasonably easy to diagnose, but diagnosing the underlying cause may
be more difficult. Packed cell volume (PCV) is one measurement of the RBC
count. Normal PCV values vary depending on the species of animal and the
laboratory being used. An abnormally low PCV value confirms the diagnosis of
anemia. If anemia is diagnosed, other laboratory tests may be recommended to
further characterize the cause of the anemia:
Prognosis
The prognosis for anemia alone can be good with early intervention in
reversible cases. Long-term prognosis depends on the severity of the underlying
disease and whether the underlying disease can be treated.
Copyright © 2011 by Saunders, an imprint of Elsevier Inc. All
rights reserved.
Kristi S. Lively, DVM, DABVP
BASIC INFORMATION
Description
Anemia is an abnormally low red blood cell (RBC) count. The primary function of
the RBC is to transport oxygen to tissues, so inadequate RBC numbers cause
decreased oxygenation of tissues. Anemia is not a specific disease but reflects
an underlying disease process.
Causes
Anemia may be caused by decreased production of RBCs, increased destruction of
RBCs (hemolysis), or loss of RBCs. Decreased RBC production arises secondary to
chronic metabolic diseases, such as kidney disease, cancer, or malnutrition.
RBCs are produced in the bone marrow, and infections or cancer of the marrow
may also affect production. Excessive RBC destruction is commonly immune
mediated, although toxins, infections, blood parasites, cancer, drug reactions,
and inherited RBC membrane defects can also cause hemolysis. Anemia secondary
to blood loss may be overtly noted with trauma, but it may be hidden with other
conditions, such as gastrointestinal tract bleeding, certain parasites (fleas,
ticks, hookworms), and clotting disorders.
· Evaluation of a blood smear to identify potential blood parasites ·
Biochemistry profile and urinalysis to evaluate organ function · Fecal
examination to identify internal parasites · Reticulocyte count to determine
whether the bone marrow is trying to replace lost RBCs · Bone marrow aspiration
and evaluation if there is no evidence that the RBCs are regenerating (low
reticulocyte count) · X-rays to evaluate for the presence of tumors, size of
various organs, or evidence of trauma · Clotting tests if excessive or
persistent bleeding is present · Other tests to screen for potential
immune-mediated destruction of RBCs
TREATMENT AND FOLLOW-UP
Treatment Options
If the anemia is severe and life-threatening, hospitalization and blood
transfusions may be recommended to stabilize the patient while the underlying
disease is identified and potentially treated. Patients with severe anemia may
also require oxygen therapy to compensate for decreased oxygen delivery to
tissues. The treatment plan is then directed at the underlying cause and may
include immunosuppressive drugs, antibiotics, parasite control, chemotherapy,
or hormone injections. Not all underlying causes of anemia are treatable.
Clinical Signs
Clinical signs of anemia depend on both the severity of the anemia and the
underlying cause. Clinical anemia typically causes weakness, lethargy,
increased heart rate, poor appetite, and pale gums. Signs of the underlying
cause may include fever, jaundice, enlarged spleen, pica (eating abnormal
objects such as dirt), enlarged lymph nodes (glands), vomiting, diarrhea,
weight loss, or depression.
Follow-up Care
Follow-up depends on the underlying cause. Isolated events such as trauma may
require monitoring of the PCV for a few days, whereas chronic conditions such
as cancer or renal disease may require long-term monitoring. Immune-mediated
anemia usually requires several months of therapy and monitoring.
Diagnostic Tests
Anemia is reasonably easy to diagnose, but diagnosing the underlying cause may
be more difficult. Packed cell volume (PCV) is one measurement of the RBC
count. Normal PCV values vary depending on the species of animal and the
laboratory being used. An abnormally low PCV value confirms the diagnosis of
anemia. If anemia is diagnosed, other laboratory tests may be recommended to
further characterize the cause of the anemia:
Prognosis
The prognosis for anemia alone can be good with early intervention in
reversible cases. Long-term prognosis depends on the severity of the underlying
disease and whether the underlying disease can be treated.
Copyright © 2011 by Saunders, an imprint of Elsevier Inc. All
rights reserved.