Hypereosinophilic syndrome

From Dog

Hypereosinophilic syndrome is a rare idiopathic disorder of dogs characterized by eosinophilia > 5 x 109/L and marked increased in circulating immunoglobulin E[1] in the absence of paraneoplastic lymphoma[2][3] or other underlying disease.

A number of breeds appear to be predisposed, including the Rottweiler, German Shepherd, Siberian Husky, Alaskan Malamute and Cavalier King Charles Spaniel[4].

The syndrome is associated with infiltration of eosinophils in many organs, leading to hepatitis[5] and multiple organopathy[6].

This syndrome is characterized by a variable eosinophilia as well as a massive infiltration of several organs by mature eosinophils, leading to organ dysfunctions and sometimes resulting in death[7].

Clinically affected dogs often present with episodic vomiting, diarrhoea, abdominal discomfort and coughing. These symptoms are often referable to underlying eosinophilic enteritis and eosinophilic bronchopneumopathy[8].

Blood tests confirm a marked hypereosinophilia, with bone marrow aspiration biopsies revealing hyperplasia of the eosinophilic cell line with no evidence of abnormal blast activity. Bronchoalveolar lavage usually shows increased numbers of eosinophils in the wash fluid and biopsies of various organs usually shows eosinophilic infiltrates in many organs[9].

Cytogenetic analysis and measurement of serum IgE concentrations are used to differentiate hypereosinophilic syndrome from eosinophilic leukemia.

Exclusions of other causes of eosinophilia such as parasites, hypoadrenocorticism, leukemia, fungal infections, eosinophilic enteritis, eosinophilic cellulitis, eosinophilic bronchopneumopathy[10] and mast cell tumors[11] are important before establishing a diagnosis.

Many cases respond to immunosuppressive doses of glucocorticoids[12] and hydroxyurea.

Some cases eventually resolve spontaneously.


  1. Sykes JE et al (2001) Idiopathic hypereosinophilic syndrome in 3 Rottweilers. J Vet Intern Med 15(2):162-166
  2. Marchetti V et al (2005) Paraneoplastic hypereosinophilia in a dog with intestinal T-cell lymphoma. Vet Clin Pathol 34(3):259-263
  3. Wallace M et al (2012) What is your diagnosis? Hypereosinophilia in a dog with multicentric B-cell lymphoma. J Am Vet Med Assoc 240(9):1063-1065
  4. Lilliehöök I & Tvedten H (2003) Investigation of hypereosinophilia and potential treatments. Vet Clin North Am Small Anim Pract 33(6):1359-1378
  5. James FE & Mansfield CS (2009) Clinical remission of idiopathic hypereosinophilic syndrome in a Rottweiler. Aust Vet J 87(8):330-333
  6. Drouot S et al (2007) Acute idiopathic hypereosinophilic syndrome in a rottweiler. Schweiz Arch Tierheilkd 149(11):511-516
  7. Aroch I et al (2001) Disseminated eosinophilic disease resembling idiopathic hypereosinophilic syndrome in a dog. Vet Rec 149(13):386-389
  8. Clercx C et al (2000) Eosinophilic bronchopneumopathy in dogs. J Vet Intern Med 14(3):282-291
  9. Perkins M & Watson A (2001) Successful treatment of hypereosinophilic syndrome in a dog. Aust Vet J 79(10):686-689
  10. Meler E et al (2010) Diffuse cylindrical bronchiectasis due to eosinophilic bronchopneumopathy in a dog. Can Vet J 51(7):753-756
  11. Cowgill E & Neel J (2003) Pleural fluid from a dog with marked eosinophilia. Vet Clin Pathol 32(3):147-149
  12. German AJ et al (2002) Eosinophilic diseases in two Cavalier King Charles spaniels. J Small Anim Pract 43(12):533-538