Evaluation of the long-acting somatostatin analogue octreotide in the management of insulinoma in three dogs

Toceranib phosphate in the management of canine insulinoma: A retrospective multicentre study of 30 cases (2009-2019)

BACKGROUND

Insulinomas are the most common tumour of the endocrine pancreas in dogs. These malignant tumours have a high metastatic rate and limited chemotherapeutic options. The multi-receptor tyrosine kinase inhibitor sunitinib malate has benefit in the treatment of metastatic insulinoma in people. Toceranib phosphate, an analogous veterinary agent, may provide benefit for dogs.

METHODS

A retrospective study describing the extent and duration of clinical outcomes and adverse events (AEs) in dogs diagnosed with insulinoma and receiving toceranib.

RESULTS

Records for 30 dogs diagnosed with insulinoma and having received toceranib were identified from a medical record search of five university and eight referral hospitals. The median progression-free interval and overall survival time were 561 days (95% confidence interval (CI): [246, 727 days]) and 656 days (95% CI: [310, 1045 days]), respectively. Of the dogs for which the canine Response evaluation criteria for solid tumours tool could be applied, the majority (66.7%) showed either a complete response, partial response or stable disease. Time to clinical progression was associated with prior intervention and type of veterinary practice. Larger dogs were at increased risk for disease progression and death. No novel AEs were reported.

CONCLUSIONS

Most dogs diagnosed with insulinoma and receiving toceranib appeared to have a clinical benefit. Randomised, prospective studies are needed to better elucidate and objectively quantify the potential effect and survival benefit of toceranib therapy for management of insulinoma in dogs.

Clinical recovery of 5 dogs from amatoxin mushroom poisoning using an adapted Santa Cruz protocol for people

OBJECTIVE

To describe the clinical course, treatment, and outcome of 5 dogs following ingestion of toxic Amanita spp. mushrooms containing amatoxins using an adapted version of the Santa Cruz protocol developed for people.

CASE SERIES SUMMARY

Five dogs were presented with clinical signs compatible with amanitin toxicity with witnessed ingestion noted in 3 of 5 dogs. Clinical findings included acute onset vomiting and diarrhea, lethargy, and hepatopathy including signs of fulminant hepatic failure (increased liver enzyme activities, hyperbilirubinemia, prolonged clotting times, and hypoglycemia were noted among these cases). Urine toxicological screening confirmed the presence of Amanita toxins in 4 cases with expert mycologist speciation in the fifth. Core interventions included percutaneous biliary drainage, use of octreotide, and early nil per os orders. All dogs survived to discharge with this treatment strategy.

NEW OR UNIQUE INFORMATION PROVIDED

This case series describes the use of a modified version of the Santa Cruz protocol to address amatoxin-induced fulminant hepatic failure in dogs. The protocol was safe, well tolerated, and all patients made a full clinical recovery.

Diagnosis of insulinoma in a Maine Coon cat

Case summary

A 14-year-old male neutered Maine Coon cat presented with a 6-month history of polyphagia and one recent episode of tremors and weakness. Blood work revealed profound hypoglycemia and results of a paired insulin glucose test were consistent with an insulinoma. Abdominal ultrasound revealed a solitary pancreatic mass, and results of a fine-needle aspirate (FNA) gave further support for the location of the neuroendocrine tumor. After unsuccessful medical management of the hypoglycemia, the mass was surgically removed. Immunohistochemistry confirmed that it was an insulinoma. At the time of writing, the patient had been in clinical remission for 9 months.

Relevance and novel information

Feline insulinomas are rare and there is very little information on their behavior, clinical course and histologic characteristics. This is the first reported case of an insulinoma in a Maine Coon cat and the first to describe results of an ultrasound-guided FNA of the mass. In addition, the progression of disease, histopathology and immunohistochemistry results add to the currently minimal database for feline insulinomas.

Long-Term Survival and Glycemic Control with Toceranib Phosphate and Prednisone for a Metastatic Canine Insulinoma

Canine insulinoma is a highly metastatic neoplasm that is associated with a guarded to poor prognosis in dogs with distant metastases. A median survival of 6 mo has been reported for dogs with metastatic insulinoma. The dog in this report, diagnosed with stage III pancreatic insulinoma, had long-term glycemic control with survival of over 24 mo while receiving prednisone and toceranib phosphate after partial pancreatectomy. Toceranib phosphate has been shown to be an efficacious therapy for canine mast cell tumors with increasing evidence that it may be beneficial in the medical management of neuroendocrine tumors.

Blood Glucose and Insulin Concentrations after Octreotide Administration in Horses With Insulin Dysregulation

Background

Octreotide is a somatostatin analog that suppresses insulin secretion.

Hypothesis

We hypothesized that octreotide would suppress insulin concentrations in horses and that normal (N) horses and those with insulin dysregulation (ID) would differ significantly in their plasma glucose and insulin responses to administration of octreotide.

Animals

Twelve horses, N = 5, ID = 7.

Methods

Prospective study. An oral sugar test was performed to assign horses to N and ID groups. Octreotide (1.0 μg/kg IV) was then administered, and blood was collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, 75, and 90 minute, and 2, 3, 4, 6, 8, 12, and 24 hour for measurement of glucose and insulin concentrations. Area under the curve (AUC) values were calculated.

Results

Mean AUC values for glucose and insulin did not differ between normal (n = 5) and ID (n = 7) groups after octreotide injection. Significant time (P < .001) effects were detected for glucose and insulin concentrations. A group × time interaction (P = .091) was detected for insulin concentrations after administration of octreotide, but the group (P = .33) effect was not significant.

Conclusions and Clinical Importance

Octreotide suppresses insulin secretion, resulting in hyperglycemia, and then concentrations increase above baseline as glycemic control is restored. Our hypothesis that octreotide causes insulin concentrations to decrease in horses was supported, but differences between N and ID groups did not reach statistical significance when blood glucose and insulin responses were compared. The utility of an octreotide response test remains to be determined.

Insulinoma in Dogs: A Review

Insulinomas are rare malignant functional pancreatic tumors of the β cells that retain the ability to produce and secrete insulin. Insulinomas are the most common pancreatic neuroendocrine tumor in dogs that can induce a variety of clinical signs that result from hypoglycemia and secondary neuroglycopenic and adrenergic effects. Diagnosis and treatment is considered challenging, and the prognosis can be extremely variable depending on the therapeutic choices. This review aims to summarize and update classic knowledge with current trends in the diagnosis, treatment, and prognosis of insulinomas.

Metabolic complications of endocrine surgery in companion animals

Metabolic complications of endocrine surgery occur commonly and precautions should be taken to avoid potentially life-threatening situations and to lessen expense associated with a more extended hospital stay. Common complications of endocrine surgery as well as prevention strategies will be reviewed for pancreatic, parathyroid, and adrenal surgery.

Insulinoma in a Dog With Pre-existing Insulin-Dependent Diabetes Mellitus

A 10-year-old golden retriever with a 3-year history of insulin-dependent diabetes mellitus was presented with recurring episodes of hypoglycemia and seizures. A presumptive diagnosis of an insulinoma was made based on hypoglycemia with concurrent endogenous hyperinsulinemia and unremarkable radiographic and ultrasonographic images of the chest and abdomen. A beta cell carcinoma of the pancreas with metastasis to the liver and a mesenteric lymph node was confirmed by surgery and histopathology.

Effect of octreotide on plasma concentrations of glucose, insulin, glucagon, growth hormone, and cortisol in healthy dogs and dogs with insulinoma

The inhibitory effect of the somatostatin analogue octreotide on the secretion of insulin could be used in the treatment of insulinoma. However, current information on the effectiveness of octreotide in dogs is conflicting. Therefore, the endocrine effects of a single subcutaneous dose of 50 microg octreotide were studied in healthy dogs in the fasting state (n=7) and in dogs with insulinoma (n=12). Octreotide did not cause any adverse effects. In healthy dogs in the fasting state, both plasma insulin and glucagon concentrations declined significantly. Basal (non-pulse related) GH and ACTH concentrations were not affected. A slight but significant decrease in the plasma glucose concentrations occurred. Dogs with insulinoma had significantly higher baseline insulin concentrations and lower baseline glucose concentrations than healthy dogs in the fasting state. Plasma glucagon, GH, ACTH, and cortisol concentrations did not differ from those in healthy dogs. Baseline plasma insulin concentrations decreased significantly in dogs with insulinoma after octreotide administration, whereas plasma concentrations of glucagon, GH, ACTH, and cortisol did not change. In contrast to the effects in the healthy dogs, in the dogs with insulinoma plasma glucose concentrations increased. Thus, the consistent suppression of plasma insulin concentrations in dogs with insulinoma, in the absence of an suppressive effect on counter-regulatory hormones, suggests that further studies on the effectiveness of slow-release preparations in the long-term medical treatment of dogs with insulinoma are warranted.

Hypoglycemia and irreversible neurologic complications in a cat with insulinoma

A 14-year-old spayed female domestic shorthair cat was evaluated for weakness, lethargy, decreased appetite, diarrhea, weight loss, and seizures. On physical examination, the cat appeared disoriented and had an inconsistent menace response. An insulinoma was diagnosed on the basis of normal serum insulin activity in conjunction with profound hypoglycemia and histologic examination (with immunohistochemical staining for chromogranin A and insulin) of a pancreatic mass that was removed surgically. Blood glucose concentration was within reference limits after surgery. However, neurologic abnormalities persisted, and the cat was euthanatized. Chronic hypoglycemia, associated with insulinomas, can cause irreversible neuronal changes in cats; therefore, rapid diagnosis and treatment of hypoglycemic conditions are of critical importance.

Streptozocin for treatment of pancreatic islet cell tumors in dogs: 17 cases (1989-1999)

OBJECTIVE

To determine toxic effects of streptozocin given in combination with a diuresis protocol in dogs and establish whether streptozocin is efficacious in treatment of pancreatic islet cell tumors in dogs.

DESIGN

Retrospective study.

ANIMALS

17 dogs.

PROCEDURE

Medical records were reviewed to obtain information regarding signalment, tumor stage and staging tests performed, number of streptozocin treatments, adverse effects, results of biochemical and hematologic monitoring during streptozocin treatment, tumor dimensions, duration of normoglycemia, and date of death, when applicable. Dogs were compared with a historical control group of 15 dogs treated surgically and medically.

RESULTS

58 treatments were administered to the 17 dogs. Only 1 dog developed azotemia. Serum alanine aminotransferase activity increased in some dogs but decreased when treatment was discontinued. Hematologic toxicoses were rare. Vomiting during administration was uncommon but occasionally severe. Two dogs developed diabetes mellitus after receiving 5 doses. Median duration of normoglycemia for 14 dogs with stage-II or -III insulinoma treated with streptozocin was 163 days (95% confidence interval, 16 to 309 days), which was not significantly different from that for the control dogs (90 days; 95% confidence interval, 0 to 426 days). Two dogs had rapid resolution of paraneoplastic peripheral neuropathy, and 2 others had measurable reductions in tumor size.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that streptozocin can be administered safely to dogs at a dosage of 500 mg/m2, IV, every 3 weeks when combined with a protocol for induction of diuresis and may be efficacious in the treatment of dogs with metastatic pancreatic islet cell tumors.

Endocrine tumors

Because of the diverse nature of endocrine organs, and their vast range of physiologic functions, endocrine tumors encompass a wide range of origination sites and disease entities. The clinical picture of affected individuals is highly dependent on the tissue of origin, and the presence or absence of functional hormone secretions. Identification, localization, and therapeutic strategies, as well as prognosis can vary greatly. Many endocrine tumors have been described in human as well as veterinary patients. This article focuses on endocrine tumors of dogs and cats. Various tumors affecting the pancreas, thyroid, parathyroid, adrenal and pituitary glands are described, including insulinoma, gastrinoma, glucagonoma, and thyroid carcinoma, as well as parathyroid hormone- and growth hormone-secreting tumors. The syndrome of multiple endocrine neoplasia is also described.

Scintigraphic diagnosis of insulinoma in a dog

Diagnosis of insulin-secreting tumors of the pancreas can usually be made on the basis of endocrine testing and exclusion of other causes of hyperinsulinism. In dogs, these tumors have a poor long-term prognosis due to a high rate of metastases and recurrence; staging (and therefore prognosticating) is difficult and usually done at the time of surgery. The purpose of this article is to describe a canine patient with an insulinoma, discuss the diagnostic imaging options for tumor evaluation and mention future directions for therapy. Insulinoma was suspected in an 8-year-old intact male Irish Setter. Somatostatin receptor scintigraphy using indium In-111 pentetreotide was performed and an area of increased radiopharmaceutical accumulation was found craniomedial to the right kidney. At surgery a small mass lesion in the pancreas and a larger, closely associated mass involving a mesenteric lymph node were removed. Histopathology confirmed the diagnosis of insulinoma with regional lymph node metastasis. The dog recovered from surgery and remained normal fourteen months later.

Evaluation of somatostatin analogues for the detection and treatment of gastrinoma in a dog

Gastrinomas in dogs are difficult to diagnose, localise and treat. In humans, somatostatin analogues have improved localisation and treatment of gastrinomas. The somatostatin analogues pentetreotide and octreotide were evaluated for the detection and treatment of gastrinoma in a dog. 111indium-pentetreotide scintigraphy revealed multiple areas of activity in the patient's mid-ventral abdomen which were consistent with masses in the pancreas and liver at laparotomy. Immunohistochemistry, electron microscopy and binding of 125I-[Tyr3]-octreotide in vitro confirmed the lesion as a gastrinoma which expressed somatostatin receptors. Octreotide at doses of 2, 4 and 8 micrograms/kg caused transient decreases in circulating gastrin. Plasma somatostatin peaked at one hour after octreotide and was still detectable at four and six hours after administration of octreotide. Combination therapy with famotidine, omeprazole, sucralfate and increasing doses of octreotide allowed patient survival for 14 months.