Hemophagocytic syndrome, also called hemophagic histiocytosis, is a form of histiocytosis, an abnormal increase in the number of certain immune cells, called histiocyte cells. Histiocyte cells include monocytes, macrophages, and dendritic cells. The extra activated macrophages, engulfing erythrocytes, leukocytes, platelets, and their precursor cells may form tumors in various parts of the body. Histiocytic disorders of dogs include histiocytoma, localized histiocytic sarcoma (HS), disseminated histiocytic sarcoma (malignant histiocytosis ), and the reactive types of histiocytosis (cutaneous and systemic). The disease been associated with a variety of viral, bacterial, fungal, and parasitic infections, such as Lyme disease. Hemophagocytic syndrome of any cause is potentially life-threatening. Breeds affected include the Bernese Mountain Dog, Golden Retriever, Rottweiler, Labrador Retriever, Schnauzer, and Tibetan Terrier.
Clinical signs associated with hemophagocytic syndrome include fever, jaundice, enlarged spleen and liver, and diarrhea. Of central nervous system manifestations, seizures are the most commonly reported. Overall, dogs with infection-associated hemophagocytic syndrome have better 1-month survival rates than dogs with immune-associated and idiopathic hemophagocytic syndrome. Therapy is dictated by the underlying diagnosis.
histiocytosis - an abnormal increase in the number of histiocyte cells
erythrocyte - red blood cell