Elevated Eosinophils in Dogs

Updated April 17, 2017

A complete blood count helps the vet form a picture of what is going on inside your dog's body. Each blood cell is counted by type, and abnormal numbers can point toward the type of illness. Eosinophils are one of the cell types seen on lab reports, and an elevated count is eosiniphilia.

What They Look Like

A type of white blood cell, eosinophils appear under a microscope as round with a pink cell membrane and a purple, multi-lobed nucleus. Its hallmark is the mass of pink crystals within the cell, which is unique to eosinophils.

What They Do

Produced in the bone marrow, eosinophils travel through the bloodstream, engulfing and neutralising invading particles. They also release proteins that can help defend the body against parasitic and allergic conditions.

Too Many Eosinophils

Too many eosinophils in the blood is known as eosinophilia, and is the result of either an allergic reaction, a parasitic infestation, or a bowel or pulmonary condition.

Eosinophilic Diseases

The most common causes of eosinophilia are food or flea allergies, or an infestation of roundworms, hookworms or whipworms. Many cancers and chronic conditions, such as Cushing's disease, can also elevate the eosinophil count as the body mistakenly mounts an attack on what it sees as a foreign invader, when the invader is borne from within.


Eosiniphilia is a symptom, not a disease, so treatment would focus on the condition that's causing it. The eosiniphil count would naturally fall as treatment progressed. Eosinophil counts may be used a barometer to monitor the success of the treatment for the condition that is causing the eosinophilia.

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