• Open Access

Prospective Evaluation of Biweekly Streptozotocin in 19 Dogs with Insulinoma

Authors

  • N.C. Northrup,

    Corresponding author
    • Department of Small Animal Medicine and Surgery, University of Georgia, College of Veterinary Medicine, Athens, GA
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  • K.M. Rassnick,

    1. Department of Clinical Sciences, Cornell University, College of Veterinary Medicine, Ithaca, NY
    Current affiliation:
    1. Veterinary Medical Center of Central New York, East Syracuse, NY
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  • T.L. Gieger,

    1. Department of Small Animal Medicine and Surgery, University of Georgia, College of Veterinary Medicine, Athens, GA
    Current affiliation:
    1. the Veterinary Clinical Sciences Department, Louisiana State University, Baton Rouge, LA
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  • C.E. Kosarek,

    1. Department of Small Animal Medicine and Surgery, University of Georgia, College of Veterinary Medicine, Athens, GA
    Current affiliation:
    1. Animal Cancer Care Clinic, Fort Lauderdale, FL
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  • C.W. McFadden,

    1. Carolina Veterinary Specialists, Charlotte, NC
    Current affiliation:
    1. Carolina Veterinary Specialists, Matthews, NC
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  • M.P. Rosenberg

    1. Veterinary Cancer Group, Tustin, CA
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  • Results of this study were presented in part at the Veterinary Cancer Society 28th Annual Conference, Seattle, WA, 2008

Corresponding author: N.C. Northrup, DVM, DACVIM (Oncology), Department of Small Animal Medicine and Surgery, University of Georgia, College of Veterinary Medicine, 501 D.W. Brooks Drive, Athens, GA 30602; e-mail: northrup@uga.edu.

Abstract

Background

Administration of streptozotocin (STZ) at a 21-day interval has been described in dogs with stage II and III insulinoma. Myelosuppression was not observed, suggesting the possibility of increasing dose intensity by decreasing the interval between doses.

Objective

To describe the tolerability of a biweekly STZ protocol. A secondary objective was to describe the outcome of dogs treated with this protocol.

Animals

Nineteen dogs with residual local, metastatic, or recurrent insulinoma.

Methods

After surgery for insulinoma, or at the time of recurrence, dogs were treated with a previously described STZ and saline diuresis protocol. Treatments were administered every 14 days. All dogs received antiemetic treatment. Adverse events (AEs) were recorded and graded. Outcome endpoints assessed were progression-free survival (PFS) and survival.

Results

None of the dogs experienced neutropenia or thrombocytopenia. Mild to moderate gastrointestinal toxicity was the most common AE. Diabetes mellitus was observed in 8 dogs and, in 6, resulted in euthanasia or death. Two dogs developed nephrotoxicity manifested as Fanconi syndrome in 1 and nephrogenic diabetes insipidus in the other. Six dogs developed increased alanine amino transferase activity. Hypoglycemia at the end of the STZ infusion, resulted in collapse in 1 dog and a generalized seizure in another. The median overall PFS and survival time were 196 and 308 days, respectively.

Conclusions and Clinical Importance

Streptozotocin can be safely administered to dogs with insulinoma, but serious AEs are possible. Additional investigation is required to better define the role of STZ in managing dogs with insulinoma.

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