Exotis ISSN 2398-2985

Ferrets

Insulinoma

Synonym(s): Islet cell tumor/neoplasia, Beta cell tumor/neoplasia

Contributor(s): Cathy Johnson-Delaney, David Perpinan

Introduction

  • Cause: currently unknown.
  • Signs: variable from lethargy, slight incoordination (ataxia), stargazing and weakness in the hind limbs to complete collapse, generalized seizures and coma.
  • Diagnosis: blood biochemistry, diagnostic imaging, exploratory surgery.
  • Treatment: pancreatectomy, glucocorticoids.
  • Prognosis: better compared with dogs, in which metastases are very common.
  • Insulinomas or islet cell tumors are, usually, small (0.5-2 mm) tumors of the pancreatic beta cells.
  • Results in the production of excessive amounts of insulin and subsequent hypoglycemia.
  • Tumor types may be described as hyperplasia, adenomas or carcinomas.
  • Most are well circumscribed, but infiltration in surrounding tissues may occur.
  • In contrast to dogs, insulinomas in ferrets rarely metastasize.
Print off the Owner Factsheet on Insulinoma to give to your clients.

Pathogenesis

Etiology

  • The etiology of insulinomas in ferrets is currently unknown.
  • The limited genetic diversity of ferrets, which stem from a limited number of breeder farms, has led to the suggestion that a genetic component may be involved.
  • Another theory suggests that, based on the natural carnivorous diet of mustelids, diets high in carbohydrates may contribute to the development of these tumors.
  • A diet high in protein (42-55%  on a dry matter basis), high in fat (18-30% on a dry matter basis), low in carbohydrates (8-15% on a dry matter basis), and low in fiber (1-3% on a dry matter basis) has therefore been advised to reduce the incidence.
  • Alternatively, feeding commercial balanced diets based on entire prey animals has been recommended.
  • No scientific evidence, however, is available to back up any claims on the etiology of insulinoma, nor has it been proven that the incidence is reduced when ferrets are fed prey based diets or low-carbohydrate kibble.
  • The 'modern' keeping of ferrets (early neutering, kibble diet, indoor housing and probably certain genetics) is associated with a higher incidence of insulinomas when compared with other classic husbandry practices. Geographical differences in incidence are believed to be caused by differences in these factors.

Pathophysiology

  • Most ferret insulinomas express insulin, chromogranin A and neuron-specific enolase.
  • Most ferrets diagnosed with insulinoma have between 1 and 5 nodules.
  • Most nodules (56%) are in the left lobe of the pancreas (30% on the right lobe and 14% on the body of the pancreas).
  • Very low rate of metastases; about 7% of tumors metastasize to regional lymph nodes, liver and spleen.
  • A large number of ferrets (85%) that present with insulinoma have concurrent disease: splenomegaly, adrenal tumors, cardiomyopathy, stomach hair balls, lymphoma, etc.
  • Hyperplasia, adenoma and adenocarcinoma are the most common histologic changes.

Epidemiology

  • Prevalence is considered 20-25% of diagnosed ferret neoplasms.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Bennett K R, Gaunt M C & Parker D L (2015) Constant rate infusion of glucagon as an emergency treatment for hypoglycemia in a domestic ferret (Mustela putorius furo). J Am Vet Med Assoc 246 (4), 451-454 PubMed.
  • Petritz O A, Antinoff N, Chen S, Kass P H & Paul-Murphy J R (2013) Evaluation of portable blood glucose meters for measurement of blood glucose concentration in ferrets (Mustela putorius furo). J Am Vet Med Assoc 242 (3), 350-354 PubMed.
  • Chen S (2010) Advanced diagnostic approaches and current medical management of insulinomas and adrenocortical disease in ferrets (Mustela putorius furo). Vet Clin North Am Exotic Anim Pract 13 (3), 439-452 PubMed.
  • Caplan E R, Peterson M E et al (1996) Diagnosis and treatment of insulin-secreting pancreatic islet cell tumors in ferrets: 57 cases (1986-1994). J Am Vet Med Assoc 209 (10), 1741-1745 PubMed.
  • Chen S (2008) Pancreatic endocrinopathies in ferrets. Vet Clin North Am Exotic Anim Pract 11 (1), 107-123 PubMed.
  • Weiss C A, Williams B H & Scott M V (1998) Insulinoma in the ferret: clinical findings and treatment comparison of 66 cases. J Am Anim Hosp Assoc 34 (6), 471-475 PubMed

Other sources of information

  • Schoemaker N J & van Zeeland Y R A (2017) Disorders of the Endocrine System. In: Ferret Medicine and Surgery. Ed: Johnson-Delaney C A. CRC Press, USA. pp 191-218.
  • Miller C M, Marini R P & Fox J G (2014) Diseases of the Endocrine System. In: Biology and Diseases of the Ferret. 3rd edn. Eds: Fox J G & Marini R P. Wiley Blackwell, Ames, USA. pp 377-400.
  • Rosenthal K L & Wyre N R (2012) Endocrine Diseases. In: Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery. 3rd edn. Eds: Quesenberry K E & Carpenter J W. Elsevier, St. Louis, USA. pp 86-102.


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