Paraneoplastic Syndromes in Dogs
Paraneoplastic syndromes may be seen in any dog with a malignant (most common) or benign tumor (rare). Paraneoplastic syndromes (PNS) are a group of disorders that result from the abnormal secretions of a hormone or hormone-like product from a cancerous tumor, or from the body's immune response to the tumor. These secretions affect the related tissues or organs (that is, the tissues and organs that are directly related to the affected organ) and generate an abnormal clinical response in dogs dealing with cancer.
Such a response is not due to the invasiveness of the primary tumor, but is a secondary response to the abnormal secretions that are produced by the malignant or benign tumor. Symptoms depend on the response of the tissue or organ that is being targeted.
Symptoms and Types
The symptoms will vary greatly depending on the type of tumor and on the organ system being affected by the abnormal secretions from such tumors. This type of disorder is most commonly related to a malignant tumor, but it can also result from a benign tumor that is secreting hormones. This latter type of tumor is rarer than the malignant type, in this instance.
- Hair loss (alopecia)
- Physical wasting and loss of weight (cachexia)
- Stomach and intestine ulcers
- Low body glucose levels (hypoglycemia)
Other symptoms depending on the type, location, and stage of tumor.
Tumor and/or presence of cancer in the body; hormone or hormone-like secretions released by the tumor.
You will need to give a thorough history of your dog's health and onset of symptoms. The history you provide may give your veterinarian clues as to which organs are causing secondary symptoms. After taking a complete history, your veterinarian will conduct a detailed physical examination. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. These laboratory tests will return evidence of an immune system response to the cancer, and will also measure the effects the tumor secretions are having on various tissues and organs in the body.
Imaging studies will include radiographs of the thoracic (chest) cavity to rule out cancer in the lungs, and of the abdomen to confirm or rule out cancer of the organs situated therein. Ultrasound imaging will also be used to examine the structure of the internal organs and the adrenal glands. Biopsies of affected organs may be taken for further diagnosis, and if skin disorders are present, samples will betaken of the affected areas.
Treatment of such disorders is highly individualized and will depend on the type, location, and stage of the tumor. If your dog has been suffering from anorexia and wasting, it will need to be placed on nutritional support and stabilized before further invasive treatments can begin. Invasive treatment is necessary, under the circumstances, as the type of tumor is most likely of a highly malignant nature. Your veterinarian will remove the tumor, if possible. Chemotherapy may also be an option, if the tumor is of the type that is likely to respond to chemical therapy. Your doctor will discuss these options with you.For some patients, where the underlying tumor cannot be removed or treated, management of the clinical signs and treatments to improve the quality of life will be planned.
Living and Management
The overall prognosis depends on the underlying tumor and its treatment, but in general, the malignant nature of the tumors that cause paraneoplastic syndromes often leads to a fatal outcome.
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