Anemia
DEFINITION/OVERVIEW
Anemia is a sign of disease and is characterized by a decreased number of erythrocytes, hemoglobin deficiency or both. It can occur due to one of four main categories: decreased erythropoietic activity, hemorrhage, destruction of red blood cells, or sequestration.
ETIOLOGY/PATHOPHYSIOLOGY
Traumatic
Hemorrhagic
Maladaptation syndrome associated anemia: reported in stressed reptiles, associated with captivity or with capture of wild reptiles
Blood parasites
Virus associated anemia
Autoimmune hemolytic anemia: rare in reptiles
SIGNALMENT/HISTORY
Wild‐caught reptiles or those housed under poor husbandry conditions may be more predisposed.
CLINICAL PRESENTATION
Nonspecific clinical signs including lethargy, anorexia, and behavioral changes.
Pallor of skin and mucus membrane color may also be observed.
RISK FACTORS
Husbandry
Inadequate husbandry, including diet, is often a predisposing factor for many diseases of captive reptiles.
Any reptile maintained under poor husbandry conditions should be considered susceptible to disease.
Wild‐caught reptiles are more likely to have underlying diseases, especially endoparasites and hemoparasites, which may be the underlying cause of chronic anemia.
Others
Any reptile with a chronic illness may be predisposed to anemia.
DIFFERENTIAL DIAGNOSIS
Trauma leading to external or internal hemorrhage.
Maladaptation syndrome associated anemia—reported in stressed reptiles, associated with captivity or trapping of wild reptiles.
Hemoparasites
Malnutrition
Toxicity
Weakness and prostration due to metabolic bone disease, pregnancy, or infectious disease.
DIAGNOSTICS
Blood sampling is essential for diagnosis and monitoring of anemic reptiles.
Patient’s size, condition, and venous access must all be considered.
Venipuncture sites with minimal lymphatic contamination are preferred, to obtain a more representative sample of the peripheral blood.
In chelonians, the jugular vein is the site with the least amount of lymphatic contamination.
Alternatively, the brachial plexus and coccygeal veins can be sampled.
The subcarapacial sinus tends to have the largest amount of lymphatic contamination.
In critically ill, possibly anemic, reptiles, aim to collect a blood volume of no more than 0.5% of the body weight (0.5 ml/100 g body weight) so as to not exacerbate the anemic condition.
EDTA can cause hemolysis and artifacts in most chelonian, so lithium heparin is the preferred anticoagulant.
Physical Exam
Mucous membranes and general pallor—compared with mammals, reptiles’ mucous membranes are lighter in color but should still appear pink.
One exception is the family Chelydridae, which normally have rather pale mucous membranes.
Examination of the ocular conjunctiva and even the iris color in American box turtles (Terrapene sp.) has also been reported, associating the pale iris with low hematocrit and possible anemia.
Hematology
Although there is limited ability to assess all the same hematologic parameters as in mammals, some basic guidelines can be found for certain values.
Hematocrit/PCV
Normal values range from 20 to 45. Values below 20 suggest anemia in most cases.
A blood transfusion should be considered in animals with values below 10, although there is little research in reptilian blood transfusions.
Seasonal variations in this parameter should also be considered before making clinical decisions.
A low hematocrit with an increased polychromasia index is a normal physiologic change during brumation, but pathologic during the active season.
Hemoglobin
Normal values are 6–10 g/dl according to the species.
Lower values should suggest anemia. MCHC is calculated according to the hematocrit and hemoglobin, like MCH; these parameters show variation in case of anemia.
Individual variations should also be considered, as reptiles have different types of hemoglobin, which may influence the expression of clinical signs.
Polychromasia and Erythroblasts
An increased polychromasia and erythroblasts in general suggests an increased need for erythrocytes in peripheral blood and can be interpreted as evidence of a regenerative anemia.
Occasionally, a high number of erythroblasts may be found in the micro‐hematocrit tube, forming an intermediate layer between the buffy coat and the red
