Rouleaux formation is most commonly seen on blood smears from which species?

Rouleaux formation is most commonly seen on blood smears from which species?

• A. Dogs
• B. Cats
• C. Horses
• D. Goats

Answer: (C)

Rouleaux formation is red blood cells stacking in long, coin-like columns because of increased plasma proteins, especially fibrinogen and globulins. This effect surfaces most prominently in horses, where plasma protein levels that promote rouleaux are more commonly elevated, particularly during inflammatory or infectious processes. In dogs and cats, rouleaux can occur but is less typical under normal conditions, and goats are not usually noted for this finding on routine smears. So the appearance of rouleaux on a blood smear is most characteristically seen in horses. If you want a quick check during a smear, you can assess whether the stacks disperse with saline; true rouleaux break up with dilution, whereas genuine agglutination does not.

Rouleaux formation is red blood cells stacking in long, coin-like columns because of increased plasma proteins, especially fibrinogen and globulins. This effect surfaces most prominently in horses, where plasma protein levels that promote rouleaux are more commonly elevated, particularly during inflammatory or infectious processes. In dogs and cats, rouleaux can occur but is less typical under normal conditions, and goats are not usually noted for this finding on routine smears. So the appearance of rouleaux on a blood smear is most characteristically seen in horses. If you want a quick check during a smear, you can assess whether the stacks disperse with saline; true rouleaux break up with dilution, whereas genuine agglutination does not.