Why Is My Dog Or Cat's Blood Sample Hemolized ?












Ron Hines DVM PhD

To see what normal blood and urine values are, go here

For an explanation of causes of most abnormal blood and urine tests, go here

To see how tests are grouped, go here

The Hemolysis Index Of Your Pet’s Blood Sample

Hemoglobin (Hb), the red blood pigment that carries oxygen, belongs in your dog or cat’s red blood cells (erythrocytes). When it escapes into solution during or after a blood sample is collected, the sample is said to be hemolized. When it escapes while still in the blood stream, a process called intravascular hemolysis has occurred.

The second cause is quite rare - but both conditions, when substantial, can falsely alter some of your pet’s other blood test results. Some of those altered values can be adjusted to correct values using mathematical formulas. But it is always wise to obtain a new sample and resubmit it. Misleading results possible due to hemolized blood samples include elevated blood potassium, phosphate, CK, AST, LDH, uric acid and magnesium and decreased AP, amylase and GGT levels.



Reasons Why Your Pet's Blood Sample Might Be Reported As Hemolized :

About 90% of the time, it was due to the blood sample being collected too fast, too slow, with too much suction on the syringe plunger or through too narrow a gauge needle.

Animal hospitals get busy with unexpected emergences. Veterinarians and their staff are human and get stretched thin at times.

Too long a time at room temperature between obtaining the sample and running it or accidentally freezing the sample can also cause hemolysis.

Veins can be quite difficult to withdraw blood from – particularly when your pet has health problems that decrease blood pressure, when the vein has been tapped many times before or when the pet is squirmy. In those pets, the jugular vein of the neck is usually the location of choice. Some pet owners resent a jugular blood draw. But it is not painful. If you pet was ill enough to require a blood draw, your vet needs the best sample possible.

Blood samples that contain a lot of lipid (fat, lipemia), either because of medical issues or because of a recent meal, are also more likely to hemolized. Altered blood Na and K values, certain diseases, such as diabetes or inherited RBC defects make red blood cells more likely to lyse (rupture) during collection.

Reasons Why Your Pet’s Blood Might Hemolyze While Still In Its Blood Stream (aka hemoglobinemia, intravascular hemolysis, Increased RBC Fragility) :

Autoimmune hemolytic anemia, other autoimmune lupus-like diseases, blood parasites (eg babesia) or a mismatched blood transfusion can all cause blood to hemolized while still in the circulation (intravascular hemolysis).

Certain bacterial infections (eg Clostridium, Leptospira), snake bite, spider bite, overwhelming bee stings can cause intravascular hemolysis as well.

Zinc poisoning, onion poisoning, low blood phosphate levels and Heinz Body anemia have also caused this problem as well as increasing the chances of a blood sample hemolyzing during collection.

Disease like diabetes that lower blood phosphate, inherited RBC defects and inherited enzyme deficiencies (phosphofructokinase or pyruvate kinase deficiency) have also resulted in intravascular hemolysis that cause blood to lyse while still in the body.

Any abnormal constriction in your pet’s circulatory system, such a a scarred or constricted heart valve, blood vessel tumor (hemangiosarcoma), DIC, kidney scarring (glomerulosclerosis) that causes blood turbulence as RBCs pass through it (= fragmentation or angiopathic hemolytic anemia) can liberate free hemoglobin into the pet's blood stream. Red blood cells are rather fragile.

Complementary tests :

Obtain another blood sample and repeat the blood tests.
CBC/WBC and blood chemistry panel (including blood bilirubin levels), urinalysis for hemoglobinuria, bilirubin level in urine (bilirubinuria), ANA test, coombs test, globulin, IgG and IgM levels