Final answer:
Eosinophilia is expected in a blood sample from an allergic dog because eosinophils are involved in allergic reactions and parasitic infections, releasing histamine which contributes to allergy symptoms.
Step-by-step explanation:
In the case of an allergic dog, one would expect to see eosinophilia in a blood sample.
Eosinophils are a type of white blood cell that are part of the immune system and are particularly active during allergic reactions and infections with parasites.
When an allergic reaction occurs, eosinophils are recruited to the site of the allergy and can cause inflammation.
Eosinophils release histamine and other inflammatory mediators which contributes to the symptoms of an allergy.
Antihistamines can help alleviate these symptoms by blocking the action of histamine.
Additionally, eosinophils are also responsible for combating multicellular parasites.
Hence, an increased number of eosinophils, known as eosinophilia, is an indication commonly associated with allergic responses or parasitic infections.