Eosinophilia

Description

Eosinophilia refers to an increase in the number of eosinophils present in the blood or tissues. This form of leucocytosis is most commonly associated with parasitism or hypersensitivity reactions, including the following diseases:

• Hypersensitivity Reactions
  • Flea bite hypersensivity is the most common cause of eosinophilia in cats and it may occur in animals with signs of miliary dermatitis. Food hypersensitivity reactions and atopic dermatitis may also be variably associated with eosinophilia.
  • Feline eosinophilic granuloma complex may be associated with blood or tissue eosinophilia. The eosinophilic ulcer form is rarely associated with systemic changes whereas eosinophilia is a near constant feature of the eosinophilic plaque. The linear granuloma is variably associated with blood eosinophilia.
  • Feline hypereosinophilic syndrome is a rare cause of eosinophilia that is associated with infiltration of various organs, particularly the liver and spleen, by eosinophils.
  • Eosinophilic enteritis is a form of infiltrative enteritis which may be focal or diffuse. The latter form of disease is especially common in German shepherd dogs as an idiopathic complex that may be accompanied by blood eosinophilia. The focal form may be associated with intestinal parasite infection. Multisystemic Eosinophilic Enteritis and Dermatitis (MEED), a rare form of equine inflammatory bowel disease may also be associated with blood eosinophilia.
  • Feline asthma syndrome, canine pulmonary infiltration with eosinophils (PIE) and equine eosinophilic pulmonary granulomas may all be associated with blood eosinophilia.
• Parasite Infection - Both endo- and ecto-parasite infections may result in blood eosinophilia, in particular:
  • Aelurostrongylus abstrusus, the feline lungworm.
  • Dirofilaria immitis which causes Heartworm.
  • Gastro-intestinal parasites including Toxocara canis and the other toxascarids of dogs and cats.
• Miscellaneous
  • The rare form of eosinophilic chronic myeloid leukaemia may result in the abnormally high production of eosinophils.
  • Hypoadrenocorticism or Addison's disease may be associated with eosinophilia, a feature that may help to differentiate it from other diseases as such severely ill animals would usually be expected to have a stress leucogram.
  • Eosinophilia may occur in pregnant small animals.
  • German shepherd dogs are particularly prone to the development of eosinophilia and this may or may not be related to the presence of concurrent enteritis.