Cancer in Pets - Histiocytosis Histiocytosis in Dogs and Cats

Cancer in Pets - Histiocytosis
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Histiocytosis, a skin disease, is the result of the over-proliferation of white blood cells in the bone marrow, and can develop into cancer. To learn more about histiocytosis, look no further.

Histiocytosis is a skin disease that occurs in dogs when white blood cells found in bone marrow quickly proliferate. Malignant histiocytosis is a deadly form of cancer that primarily afflicts Bernese Mountain dogs, as well as Golden Retrievers, Doberman Pinschers, and Rottweilers. The prognosis for malignant histiocytosis is poor -- after diagnosis, dogs will generally pass away in a matter of months or weeks. As well as the malignant form, there are systemic and cutaneous forms of this disease, which have some treatment options.

Types of Histiocytosis:

The three varieties of histiocytosis are: 

Systemic Histiocytosis:

Systemic histiocytomas occur throughout a dog’s body. It is neither malignant or cancerous, and is most common in Bernese Mountain dogs who are young or middle aged. It generally is visible in the skin or eyes, and can also be found in lymph nodes. This chronic disease requires ongoing treatment; however, not all dogs will respond to treatment.

Cutaneous Histiocytosis:

This shows up in the skin or subcutaneous layer of a dog’s skin. Unlike the other forms of histiocytosis, this occurs in a wider variety of breeds beyond the Bernese Mountain dogs. This unsightly disease is chronic. Both cutaneous and systemic histiocytosis are easily confused, and some dogs might have both varieties at once. Where cutaneous mainly impacts the skin, the systemic form also affects organs.

Malignant Histiocytosis:

Most common in older dogs, particularly Bernese Mountain dogs, this form of histiocytosis is very deadly. Malignant histiocytosis is a rare disease, but unfortunately, there is no known treatment method to accompany the diagnosis.


The cause of histiocytosis is unknown, although given how commonly the disease affects Bernese Mountain dogs, and other specific breeds, a hereditary, genetic factor is likely. The breeds that most frequently get the malignant form of cancer, after Bernese Mountain dogs, are Golden Retrievers, Doberman Pinschers, and Rottweilers, particularly elderly dogs. Middle aged male dogs have a higher chance of being stuck with systemic histiocytosis.

Symptoms and Diagnosis:

The symptoms for these three types of histiocytomas are similar. Your dog may have respiratory problems, including trouble breathing and coughing. Dogs may also be lethargic and anxious, unwilling to eat, and experiencing weight loss. In order to diagnose histiocytosis, your veterinarian will likely do a physical, get a complete blood count, take x-rays, and potentially do biopsies. 


Unfortunately, there is currently no treatment available for malignant histiocytosis. The prognosis is poor, and dogs diagnosed with it may die within months, weeks, or days. For other forms of histiocytosis, treatment methods such as fluids, immune suppression therapy, and chemotherapy can help.

More on Types of Cancer

Mast Cell Cancer in Pets 
Bone Cancer in Pets
Lymphoma in Cats and Dogs

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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