Clinical presentation of dogs (or cats) with anemia varies with the severity and duration of the anemia, and with the underlying disease. There may be few historical findings related to anemia and often it is an incidental finding when labwork is performed. Listlessness (which may also be described as lethargy, weakness or reduced exercise tolerance) and inappetence, although common complaints in dogs with anemia, are non-specific findings. Other historical complaints seen in patients with anemia can include collapse, syncope, and evidence of hemorrhage or hemolysis (icterus or pigmenturia). You may need to ask the client more specific questions to reveal this background.

A careful physical examination can provide helpful information regarding anemia. Physical examination findings in dogs with anemia depend on the underlying disease process and severity of anemia. Findings may include mucous membrane pallor, tachypnea, tachycardia, a soft systolic heart murmur (not louder than grade III/IV), and pulse changes (hyperkinetic femoral pulses). Animals with hemorrhagic shock have the above findings except that pulses will be weak, extremities cool, and a heart murmur may or may not be present. Other findings associated with specific types of anemia may include icterus (hemolysis), fever (infectious, immune-mediated, or neoplastic disease), hemorrhages (hemostatic problem, trauma), hepatosplenomegaly (immune-mediated disease, neoplasia, spenic torsion, infection), and endocrine alopecia (hypothyroidism).

Classification of anemia is an important step in determining the cause, best approach to treatment, and prognosis.

1. Severity based on hematocrit (packed cell volume, PCV) – an arbitrary classification
   

   Severity	PCV
   Mild	30–37%
   Moderate	20–30%
   Severe	10–20%
   Critical	<10%

   
   Mild, non-regenerative anemias are often caused by chronic disease and may not be worth pursuing. Anemia of chronic disease in dogs typically does not produce a hematocrit <20%, so the magnitude of anemia can be very helpful in determining cause.
2. Regenerative versus non-regenerative
   There are many laboratory indicators that an anemia may be regenerative, including macrocytosis and perhaps hypochromasia (decreased MCHC), increased anisocytosis, and presence of Howell Jolly bodies, normoblastemia, polychromasia, and reticulocytosis. Antech Diagnostics grades polychromasia on the following scale:
   

   Grade	% Polychromatic RBCs
   1+	2–5%
   2+	6–10%
   3+	11–15%
   4+	>15%

   
   The gold standard for evaluating whether anemia is regenerative or non-regenerative is the presence or absence and degree of reticulocytosis. A corrected reticulocyte percentage (%) or absolute reticulocyte number is required to correct the raw reticulocyte % for the effect of anemia.