Canine Anaplastic Histiocytic Sarcoma

Canine anaplastic histiocytic sarcoma, also known as disseminated histiocytic sarcoma or malignant histiocytosis, is a rapidly aggressive and progressive cancer. It attacks multiple systems at once, usually in the brain, bone marrow, kidneys, liver, lymph nodes, lungs and spleen. Due to the rapid progression and multiple organ involvement, prognosis is poor, though some treatment options show promise.

Non-specific symptoms of disseminated histiocytic sarcoma are anorexia, decreased energy, fever and weight loss. Other symptoms vary based on the organs affected and can include enlargement of the liver or spleen, shortness of breath, excessive coughing, seizures, lack of coordination, weakness or paralysis. Upon examination, your veterinarian may find extreme anemia, or red blood cell deficiencies, low platelet counts and high white blood cell counts.

The age of onset for disseminated histiocytic sarcoma is middle-aged to older dogs and shows no increased predisposition based on sex. While this cancer can affect any dog breed, higher occurrences are found in Bernese mountain dogs, rottweilers, flat-coated retrievers and golden retrievers, with the risk being 225 times more likely for Bernese mountain dogs than any other breed.

While little success comes from conventional treatment of disseminated histiocytic sarcoma due to its aggressive nature, some cases respond to various forms of chemotherapy, such as lomustine and doxorubicin. Because of the multi-organ involvement, surgery to remove tumors is not recommended. Prognosis is poor, and most dogs do not survive more than one year after diagnosis. Treatment focuses on reducing pain and making your dog comfortable.

Disseminated histiocytic sarcoma is a relatively rare canine tumor, though various studies have looked at different treatments and methods of early detection, especially for predisposed breeds. A 1997 study published in Clinical Cancer Research looked at the use of non-restricted cytotoxic T-cell line TALL-104 therapy for the treatment of disseminated histiocytic sarcoma, finding that the dogs responded well to treatment, with some even reaching complete remission. A 2012 study in Veterinary and Comparative Oncology discovered that serum ferritin levels might be a potential marker of early disease and recommends diagnostic imaging and ferritin levels every six months for predisposed breeds over the age of 4 years. A 2013 study published in Veterinary Journal discovered the compound dasatinib inhibits growth in histiocytic sarcoma cells.