Allergies in Dogs Symptoms | Eosinophilic Conditions Affecting Dogs

The immune system is a complex, finely tuned system involving the interplay of various components such as the lymphatic system and white blood cells (WBC). Eosinophil granulocytes represent just one type of WBC (<5%) and these are commonly referred to as eosinophils. They are involved in fighting infections and parasites but are also prominent in various allergy related conditions e.g. hay fever and atopic dermatitis.

There exists a range of canine eosinophilic conditions characterized by abnormally high levels of eosinophils in a given locality. The underlying cause for many of these conditions is currently unknown or poorly understood. However, it is believed that hypersensitivity involving an allergic response, if not the sole reason, may at least be a contributing factor in such cases. Unfortunately, elevated numbers of eosinophils and associated inflammation can be detrimental to tissue resulting in its damage.

Diagnosing eosinophilic conditions involves assessing symptoms, inflammation, as well as noting both the number and nature of the eosinophils. However, interpretation of the results varies between medical authorities due to a lack of standardization concerning the diagnostic criteria used for eosinophilic conditions.

Examples of eosinophilic conditions are shown in the table below and in many cases, they are considered to be either uncommon or rare.

CONDITION	LOCATION AFFECTED	SUSPECTED CAUSES
SKIN RELATED EOSINOPHILIC CONDITIONS:
Canine Eosinophilic Granuloma Follow link above for explanation of related terminology: Eosinophilic Granuloma Complex (EGC) and Eosinophilic dermatoses	Oral Cavity Cutaneous (Skin): Typically thighs (inner), but also face, abdomen (ventral), flanks, prepuce	Hypersensitivity is probably the primary factor Inherited (genetic) tendency probable
Canine Eosinophilic Furunculosis (Folliculitis)	Cutaneous (Skin): Typically muzzle, also face, ear flaps, abdomen or chest	Acute hypersensitivity: Primarily to bites from venomous insects or arachnids e.g. bees or spiders Possible reaction to medication
RESPIRATORY RELATED EOSINOPHILIC CONDITIONS:
Canine Eosinophilic Bronchopneumopathy (Eosinophilic bronchitis or pneumonitis)	Airways and Lungs	Hypersensitivity Parasitic
Pulmonary Infiltration with Eosinophila e.g. eosinophilic pulmonary granulomatosis	Lungs and Bronchi	Hypersensitivity
GASTROINTESTINAL RELATED EOSINOPHILIC CONDITIONS: The general term Eosinophilic Gastrointestinal Disorder (EGIDs) applies to the following conditions
Canine Eosinophilic Esophagitis	Esophagus	Food allergies and environmental Inherited (genetic) tendency probable
Canine Eosinophilic Gastritis	Stomach	Unknown Food allergies Immune-mediated i.e. autoimmune disease Parasitic
Canine Eosinophilic Gastroenteritis	Stomach and Small Intestine	Unknown Food allergies
Canine Eosinophilic Colitis	Large Intestine	Unknown Food allergies Parasitic
OTHER RELATED EOSINOPHILIC CONDITIONS:
Canine Eosinophilic Cystitis	Bladder	Hypersensitivity Possible reaction to medication
Canine Hypereosinophilic Syndrome	Infiltration can affect various locations e.g. bone marrow, GI tract, lungs, lymph nodes, spleen and possibly adrenal glands, heart, kidneys, pancreas, skin and thyroid.	Severe antigen response Immune response/ eosinophil production dysfunction