Paraneoplastic Syndromes

Paraneoplastic syndromes (PNSs) are indirect manifestations of malignancy, caused by substances like cytokines, hormones, autoantibodies, or peptides released by tumor cells. These syndromes can present with various clinical signs unrelated to the primary tumor but serve as sentinel warnings and indicators of remission status. The chapter focuses on common PNSs in veterinary medicine, such as acromegaly, cancer cachexia, and hypercalcemia, detailing their associated tumors and clinical presentations. Hypercalcemia of malignancy (HM) is the most prevalent PNS in veterinary practice, with tumor types like lymphoma and anal sac adenocarcinoma in dogs and oral squamous cell carcinoma in cats. HM is often caused by humoral factors like parathyroid hormone-related protein (PTHrP), leading to clinical signs such as polyuria, anorexia, and muscle weakness. Diagnosis involves measuring ionized calcium and further imaging or laboratory tests if necessary. Treatment primarily involves addressing the underlying tumor, with supportive care for severe cases. The chapter also discusses hyperviscosity syndrome, caused by increased blood viscosity due to elevated immunoglobulins or red blood cells, leading to poor oxygenation and hypertension.