Final answer:
The expected hematologic finding in a blood sample from an atopic dog is eosinophilia, which is an increase in eosinophil count associated with allergic reactions and hypersensitivity. Eosinophils are granulocytes that release histamine and other inflammatory compounds in response to allergens.
Step-by-step explanation:
In the context of an atopic dog, which exhibits allergic reactions and hypersensitivity, the hematologic finding we would expect to see in a blood sample is d. eosinophilia. Eosinophils are granulocytes that are involved in parasitic defenses as well as hypersensitivity and allergic reactions. In atopic conditions, allergens induce the activation of eosinophils, leading to an increase in their number, a condition known as eosinophilia. Eosinophils, along with basophils and mast cells, play a critical role in atopic reactions by releasing histamine and other proinflammatory compounds from their granules upon stimulation, which contributes to the symptoms of allergy.
Blood samples from atopic individuals not only show eosinophilia but also may indicate an interaction with other leukocytes such as monocytes and mast cells, which partake in the allergic response. Moreover, the presence of eosinophils in the blood can indicate a parasitic infection. It is, however, eosinophilia that is characteristically associated with atopic conditions and may be detected using blood tests such as the Enzyme-Linked Immunosorbent Assay (ELISA) and the Enzyme Immunoassay (EIA) which are designed to detect antigens related to the pathogen or allergen responsible.