Paraneoplastic Syndromes in Dogs
Paraneoplastic syndromes can manifest in dogs afflicted with either malignant (more common) or benign tumors (less common). These syndromes, abbreviated as PNS, encompass a range of disorders triggered by abnormal hormone or hormone-like substance secretions from cancerous tumors or the body’s immune reaction to the tumor. These secretions exert their effects on the corresponding tissues or organs directly associated with the affected organ, inducing abnormal clinical responses in dogs grappling with cancer. These responses stem not from the primary tumor’s invasiveness but rather as a secondary reaction to the abnormal secretions produced by the malignant or benign tumor. The symptoms observed vary depending on the affected tissue or organ’s response.
Symptoms and Types
Symptoms and presentations can vary significantly based on the tumor type and the specific organ system affected by the abnormal secretions. While this disorder is commonly associated with malignant tumors, it can also arise from benign tumors that secrete hormones, although such occurrences are less frequent compared to malignant tumors. Symptoms may include hair loss (alopecia), anemia, physical wasting leading to weight loss (cachexia), ulcers in the stomach and intestines, low blood glucose levels (hypoglycemia), and other manifestations contingent upon the tumor type, location, and stage.
Causes
Causes of paraneoplastic syndromes include the existence of tumors and/or cancer within the body, as well as the release of hormone or hormone-like secretions by the tumor.
Diagnosis
To diagnose paraneoplastic syndromes in your dog, it’s important to provide a comprehensive history of your dog’s health and the onset of symptoms to your veterinarian. This history can provide valuable insights into which organs may be causing secondary symptoms. Following the history, your veterinarian will perform a thorough physical examination. Diagnostic procedures will include a complete blood profile, encompassing a chemical blood profile, a complete blood count, and a urinalysis. These tests will reveal evidence of the immune system’s response to cancer and assess the impact of tumor secretions on various tissues and organs in the body.
Imaging studies will involve radiographs of the thoracic (chest) cavity to identify or rule out lung cancer and of the abdomen to confirm or rule out cancer affecting organs in that region. Additionally, ultrasound imaging will be utilized to assess the structure of internal organs and the adrenal glands. Biopsies of affected organs may be necessary for further diagnostic evaluation, and if skin disorders are present, samples will be collected from the affected areas.
Treatment
Treatment for paraneoplastic syndromes in dogs is tailored to each case and hinges on factors such as the tumor type, its location, and its stage. If your dog is experiencing anorexia and wasting, it will first require nutritional support and stabilization before more invasive treatments can be initiated. Invasive interventions become necessary, particularly if the tumor is highly malignant. Your veterinarian will explore the possibility of tumor removal, if feasible. Chemotherapy might also be considered, depending on the tumor’s responsiveness to chemical therapy. Your veterinarian will discuss these treatment options with you.
For cases where the underlying tumor cannot be surgically removed or treated, the focus shifts to managing clinical symptoms and implementing treatments aimed at enhancing your dog’s quality of life.
Living and Management
The prognosis ultimately relies on the type of underlying tumor and the effectiveness of its treatment. However, in general, the malignant nature of tumors associated with paraneoplastic syndromes frequently results in a fatal outcome.