The Effect of the Type and Concentration of Garlic (Allium sativum) on Heinz Body Concentrations in Canine Erythrocytes—An In Vitro Study

Garlic (Allium sativum) is widely used in human diets and medicine, but its safety for dogs remains uncertain. Heinz bodies in red blood cells are indicators of oxidative damage, which may lead to hemolytic anemia. This study evaluated the effects of different forms and concentrations of garlic on canine erythrocytes in vitro. The experiment consisted of two phases: Phase 1 compared fresh, dried, and granulated garlic, while Phase 2 assessed two concentrations of granulated garlic (0.1 and 0.2 g/mL). Blood from healthy dogs was incubated with ethanol extracts of garlic. Hemolysis was measured spectrophotometrically by hemoglobin release, and blood smears were examined for Heinz bodies and eccentrocytes. All garlic preparations caused hemolysis, most strongly granulated garlic at 0.2 g/mL (p < 0.01). Blood smears confirmed red blood cell damage, with more Heinz bodies and eccentrocytes in dried and granulated garlic samples. In conclusion, the form and concentration of garlic strongly influence its hemolytic activity. Processing methods such as drying and granulation may enhance the release of reactive compounds, increasing the risk of oxidative damage to canine red blood cells.