Symptoms and treatment of canine histiocytosis

Skin conditions in dogs are frequent pathological processes and are easily identified by being recognizable to the naked eye. A rare cutaneous tumor condition in dogs is canine histiocytosis, which is characterized by the appearance of plaques or nodules in the skin of different areas of the body and can even affect internal organs. histiocytic sarcoma dog, histiocytic sarcoma in dogs, epitheliotropic lymphoma, canine histiocytic sarcoma, fast growing sarcoma in dogs, golden retriever lifetime study, golden retriever cancer, purebred golden retriever puppy

Next, we will describe what this process consists of, how to identify it and what are the options for its treatment.

What is canine histiocytosis?

Histiocytosis is a pathological process in which there is an excessive proliferation of dermal cells called histiocytes. If this uncontrolled proliferation of histiocytes occurs only in the skin, we speak of cutaneous histiocytosis. If it affects other organs (liver, spleen, lungs, lymphatic system ...), it is called systemic histiocytosis. In both processes, identical skin lesions develop.
Histiocyte multiplication disorder can also lead to tumor diseases such as cutaneous histiocytoma and malignant histiocytosis (disseminated histiocytic sarcoma).

What is a histiocytoma?

A canine histiocytoma is a benign tumor that usually presents as a small, firm, button-shaped mass and can become ulcerated. It is usually an isolated mass, fast-growing and, in principle, does not take the pain.  The most affected areas are the head, ears, and legs. You can submit spontaneously within 3 months.

What signs does cutaneous/systemic histiocytosis produce?

In canine histiocytosis, multiple skin masses appear, in the form of well-defined plaques or nodules. Often these lesions ulcerate and scabs appear.

In the case of cutaneous histiocytosis, only nodules appear on the skin and usually occur more frequently on the head, neck, trunk, extremities, and scrotum. Systemic organs are not affected. These lesions are usually not painful or initially itchy, but if they ulcerate they can become a painful process for the dog.

Systemic histiocytosis affects, in addition to the skin, other internal organs, so we will have skin symptoms and general signs; the presence of multiple nodules in the skin, increased lymph nodes, ocular manifestations (conjunctivitis, retinal detachment, glaucoma ), respiratory noises, cough, anorexia, lethargy, etc. The evolution of the lesions may have periods of alternate improvement or worsening, and even spontaneous resolution can occur.

Symptoms of malignant histiocytosis

The symptoms of malignant histiocytosis in the process are more severe, with pale mucous membranes, weakness, respiratory distress and neurological signs (convulsions, paresis, etc.), the appearance of masses in the liver and/or spleen.

What dogs are predisposed to suffer from histiocytosis?

S**ual predisposition: There is no s**ual predisposition, and can affect both females and males.
Age: Cutaneous and systemic histiocytosis usually occurs in young or middle-aged dogs (average of 5 years). Histiocytoma especially affects dogs under 2 years.
Racial predisposition: Systemic histiocytosis is more common in the Swiss Mountain Range, but may affect other breeds. The cutaneous disease is not restricted to particular races. Histiocytoma is more common in Bull terrier, Boxer, Dachshund, Cocker Spaniel, Great Dane, and Shetland Shepherd.

How is canine histiocytosis diagnosed?

The veterinarian will diagnose this process by observing the clinical signs and carrying out complementary tests.

To confirm that the skin lesions correspond to a canine histiocytosis, cytology and/or biopsy of the nodules/masses detected in the skin or other organs should be performed.
Also, abdominal ultrasound and chest radiography are recommended to rule out a systemic process (systemic histiocytoma with internal organ involvement).

What is the treatment for histiocytosis?

Currently, there is no single defined treatment for this pathological process. For cases of cutaneous histiocytosis, corticosteroids are mainly used for their treatment, obtaining a total or partial remission of skin lesions. However, recurrences are frequent, and continuous treatment overtime may be necessary.

Other immunosuppressive medications such as cyclosporine, azathioprine, and leflunomide are also used, which can be combined with other medications and with other substances such as vitamin E and fatty acids.

In the case of histiocytoma, once its diagnosis has been confirmed and it is ruled out to be a type of malignant tumor, it can be expected 3 months without any therapy to see if there is a spontaneous resolution. If after this time the lesion does not remit, surgical excision or cryosurgery (burning with cold application) is recommended.

What is the prognosis of canine histiocytosis?

The prognosis for dogs with malignant histiocytosis is extremely bad since life expectancy is usually a few months after diagnosis. In the case of cutaneous and systemic histiocytosis, the prognosis depends on the response to treatment, total or partial remission of the lesions can be achieved, but recurrences are usually frequent and therapy may be necessary continuously.

For histiocytomas, surgical excision is usually a curative therapy and with it, the process is resolved.