Which of the following is the predominant white blood cell type seen on a peripheral blood smear from a dog?

The predominant white blood cell type seen on a peripheral blood smear from a dog is the lymphocyte. Lymphocytes are crucial components of the immune system, primarily involved in the body's adaptive immune response. In healthy dogs, lymphocytes typically represent a significant portion of the total white blood cell count, often ranging from 12% to 30%. They play a vital role in recognizing and responding to pathogens like viruses and bacteria.

Eosinophils, while present in blood smears, are usually more prevalent during allergic reactions or parasitic infections. Basophils are the least common type of white blood cell and are mostly involved in hypersensitivity reactions. Monocytes, while important for their role in phagocytosis and differentiation into macrophages, are less numerous than lymphocytes in a typical blood smear from a dog. Overall, lymphocytes are consistently identified as the predominant white blood cell in healthy dogs, providing a clear basis for this answer.