Anemia in cats and dogs

Definition of anemia

Anemia is defined as a decrease in the red blood cell (RBC) mass and in practical terms can be defined as a decrease in the pack cell volume (PCV), the hemoglobin (Hb) concentration, or the RBC count below reference values for the species. In special circumstances, anemia is diagnosed in a given animal with a PCV that has decreased over time, even though it may remain within reference values.

Because the reference values reflect the actual status in 95% of the feline and canine population, occasionally an “abnormal” value is indeed normal for a particular animal, prompting a needless evaluation in search of other abnormalities. It should be emphasized that anemia does not constitute a primary diagnosis; therefore every effort should be made to identify its cause.

Clinical manifestation of anemia in cats and dogs

History

1. Family history.
2. Exercise intolerance, syncopal episoded.
3. Pallor, jaundice.
4. Localized or generalized bleeding.
5. Feline leukemia virus or immunodeficiency virus infection.
6. Malnutrition, malabsorption.
7. Chronic inflammation, cancer.
8. Travel history.

Physical Examination
1. Pallor, jaundice, petechiae, ecchymoses.
2. Lymphadenopathy.
3. Hepatomegaly, splenomegaly.
4. Tachycardia, heart murmur, cardiomegaly, left-sided hypertrophy.
5. Occult blood in the stool.
6. Hematuria.

Drugs and toxins associated with anemia in cats and dogs

1. Acetaminophen.
2. Antiarrythmics.
3. Anticonvulsants.
4. Antiinflammatories (nonsteroidal).
5. Barbiturates.
6. Benzocaine.
7. Chemotherapeutic agents.
8. Chloramphenical.
9. Cimetidine.
10. Gold salts.
11. Griseofulvin.
12. Levamisole.
13. Methimazole.
14. Methionine.
15. Methylene Blue.
16. Metronidazole.
17. Penicillins and cephalosporins.
18. Phenothiazines.
19. Propylthiouracil.
20. Propylene glycol.
21. Sulfa derivatives.
22. Vitamin K.
23. Zinc.

Management of the anemic patient

The first basic principle of the management of anemic (or bleeding) patient is to collect all blood samples before instituting any therapy. Because the condition in most of these patients may constitute a true emergency at the time of presentation, often samples are not collected until the animal’s condition has been completely stabilized, resulting in treatment-induced changes in hematologic or serum biochemical values.
As a general rule, because of the acute onset of these disorders, patient with regenerative anemias (i.e., blood loss or hemolysis) require more agressive therapy than those with nonregenerative forms. Specific therapy should be instituted once the clinician has determined that the patient’s condition is stable and whether the anemia is regenerative or not.