Paraneoplastic syndromes (PNS) are neoplasm-associated alterations in bodily structure and/or function that occur distant
to the tumor. They are an extremely diverse group of clinical aberrations that are associated with the non-invasive actions
of the tumor. In many situations, the PNS parallels the underlying malignancy, and therefore, successful treatment of the
tumor leads to disappearance of the PNS. Alternatively, recurrence of the PNS after successful treatment signals recurrence
of the tumor, and the return of the PNS often significantly precedes the gross recurrence of the tumor.
PNS are often the first sign of malignancy, or the PNS may be a hallmark of a certain tumor type. Therefore, an understanding
and appreciation for the types and causes of these syndromes are paramount for early cancer detection and appropriate therapy.
In addition, PNS can cause greater morbidity than that associated with the actual tumor. Unfortunately, some PNS can be so
severe that appropriate therapies may not be instituted against the tumor, although the tumor may in fact be readily treatable
(e.g. hypercalcemic lymphoma).
Table I: Paraneoplastic Syndromes and Associated Tumors
The causes of PNS are quite variable; however, they are usually caused by the production of small molecules, which are released
into the circulation to cause effects at distant sites. In addition, there are many non-endocrine PNS with no known etiology.
Though recognized more commonly in human cancer patients, PNS do occur in veterinary medicine. Table 1 summarizes the most
common PNS of dogs and cats with the tumors that cause them. This presentation will review the wide range of PNS seen in veterinary
oncology with a system-based approach and each system-section contains a brief discussion of comparative aspects to related
human PNS when appropriate.
Table 2: Treatment for Hypercalcemia of Malignancy
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