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Postoperative Outcomes of Canine Insulinoma

Amandine Lejeune, DVM, DACVIM (Oncology), University of California, Davis


June 2022

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In the literature

Cleland NT, Morton J, Delisser PJ. Outcome after surgical management of canine insulinoma in 49 cases. Vet Comp Oncol. 2021;19(3):428-441.


Insulinomas arise from pancreatic beta cells and lead to inappropriate secretion of insulin and hypoglycemia. CT and ultrasonography have limited sensitivity and specificity for detecting pancreatic masses and metastases.1-3 Partial pancreatectomy with debulking of metastatic lesions can provide glycemic control, can alleviate clinical signs, and is associated with median survival times (MSTs) of 308 to 789 days correlated with histopathologic stage.4-7 

This retrospective study aimed to describe outcomes in a cohort of dogs (n = 49) with insulinomas treated surgically and to assess whether selected potential risk factors were strongly associated with these outcomes. 

Ultrasonography did not identify a pancreatic mass in 16 out of 40 dogs that underwent ultrasound. Abnormal lymph nodes were grossly identified and biopsied intraoperatively in 27 dogs; 19 samples were positive for metastasis on histopathology. Liver biopsy was performed due to gross abnormalities in 33 dogs; 15 were positive for metastasis. Overall, 27 dogs had metastases on histopathology. Postoperative complications occurred in 25 dogs, with pancreatitis being most common.   MST for all dogs was 561 days (range, 311-754 days), and MST for dogs that were euglycemic postoperatively was 746 days (range, 541-815 days). Pathologic tumor stage was associated with survival. MSTs were 182 days (range, 69-379 days), 574 days (range, 169-951 days), and 766 days (range, 598-1,344 days) for patients with pathologic tumor stage 3, stage 2, and stage 1, respectively.

Of the postoperative euglycemic dogs, 44% relapsed within 2 years, and median overall euglycemic time was 424 days. Persistent postoperative hypoglycemia was a negative prognostic indicator for survival time, with a 7.3-fold increase in daily likelihood of death. All patients with persistent hypoglycemia died within one year. A strong association between pathologic stage (stage 3 relative to stage 2) and persistent postoperative hypoglycemia was found.


Key pearls to put into practice:


Common clinical signs in patients with insulinoma include weakness, seizures, collapse, and tremors. Geriatric dogs with these signs should undergo blood glucose measurement and, if indicated, insulin:glucose ratio evaluation.


Ultrasonography and CT have low sensitivity for detecting insulinoma. Visual assessment of abnormal lesions may not correlate with metastasis; histopathology of abnormal lesions is warranted to provide accurate staging.


Surgical treatment should be considered even in suspected cases of clinical stage 2 or 3 disease because of the limitations of imaging and intraoperative impressions for staging. Surgical tumor reduction is the mainstay treatment for insulinoma. The most common postsurgical complications include pancreatitis (more common) and diabetes (less common).8,9 


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