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==Description==
==Description==
==Signalment==
==Signalment==
Insulinomas occur most commonly in middle-aged or older dogs of the larger breeds. There is no sex predilection and the condition occurs less commonly in cats.
Insulinomas occur most commonly in middle-aged or older dogs of the larger breeds. There is no sex predilection and the condition occurs less commonly in cats. Older cattle may rarely develop insulin-secreting tumours.
==Diagnosis==
==Diagnosis==
*'''Serum fructosamine levels''' can also be assessed to gauge whether the animal has been persistently hypoglycaemic over the previous 2-3 weeks. A level <250-350 umol/l is suggestive of insulinoma
*'''Serum fructosamine levels''' can also be assessed to gauge whether the animal has been persistently hypoglycaemic over the previous 2-3 weeks. A level <250-350 umol/l is suggestive of insulinoma
===Histopathology===
===Pathology===
This is needed for definitive confirmation of the diagnosis. The following features may be identified:
This is needed for definitive confirmation of the diagnosis. The following features may be identified:
*Usually single, or less often multiple, small (1-3cm) spherical nodules, yellow to dark red, in one or more lobes
*Usually single, or less often multiple, small (1-3cm) spherical nodules, yellow to dark red, in one or more lobes
*Small islets of acinar tissue are sometimes present within the neoplasm
*Small islets of acinar tissue are sometimes present within the neoplasm
*Pancreatic beta cells can readily be identified using immunocytochemistry
===Diagnostic Imaging===
===Diagnostic Imaging===
==Treatment==
==Treatment==
===Emergency Stabilisation===
===Emergency Stabilisation===
In the event of a hypoglycaemic episode, a bolus of 50% dextrose solution should be given immediately. Glucose syrup can also be rubbed onto the gums of an affected animal or a meal could be provided and this approach may reduce the risk of rebound hypoglycaemia encountered with administration of 50% dextrose solution. Intra-venous fluid therapy can then be maintained using 2.5% dextrose solution.
===Medical===
===Medical Management===
This is more suitable for patients in which surgery has been declined or when surgery is inappropriate or fails due to the presence of metastasis.
This is suitable for patients in which surgery has been declined or when clinical signs recur after surgical treatment due to the presence of metastases. A suitable regime would include:
*'''Small and frequent meals''' (3-6 times/day) of with high fat and protein content and some complex carbohydrate.
*'''Small and frequent meals''' (3-6 times/day) of with high fat and protein content and some complex carbohydrate.
*'''Exercise restriction'''.
*'''Exercise restriction'''.
*[[Steroids|'''Glucocorticoids''']] such as prednisolone may be prescribed to increase hepatic gluconeogenesis and to decrease cellular glucose uptake.
*[[Steroids|'''Glucocorticoids''']] such as prednisolone prescribed to increase hepatic gluconeogenesis and to decrease cellular glucose uptake.
*'''Diazoxide''', an oral hyperglycaemic drug, may be used to inhibit pancreatic insulin secretion and tissue glucose uptake.
*'''Diazoxide''', an oral hyperglycaemic drug, used to inhibit pancreatic insulin secretion and tissue glucose uptake.
*'''Octreotide''', a somatostatin analogue which reduces the synthesis of insulin, is rarely used for management of insulinomas.
===Surgery===
===Surgical Management===
A '''partial pancreatectomy''' is suitable for patients with a solitary tumour and any suspected metastases may be removed or biopsied at the same time. Possible post-operative complication include:
A '''partial pancreatectomy''' is suitable for patients with a solitary tumour and any suspected metastases may be removed or biopsied during the procedure. An intra-operative ultrasound scan can be performed if the mass is not evident when the pancreas has been exposed. Possible post-operative complications include:
*'''Persistent hypoglycaemia''', probably due to the presence of unidentified metastases
*'''Persistent hypoglycaemia''', probably due to the presence of unidentified metastases.
*[[Pancreatitis - Dog and Cat|'''Pancreatitis]]''' or '''Diabetes mellitus''' due to disruption to the pancreatic parenchyma during the procedure
*[[Pancreatitis - Dog and Cat|'''Pancreatitis]]''' or '''Diabetes mellitus''' due to disruption to the pancreatic parenchyma during the procedure.
*'''Epilepsy''' and '''diffuse polyneuropathy''' due to chronic hypoglycaemia
*'''Epilepsy''' and '''diffuse polyneuropathy''' due to chronic hypoglycaemia.
*'''Duodenal necrosis and perforation''' as the cranial pancreatico-duodenal artery may be disrupted when the right limb of the pancreas is dissected away the duodenum.
==Prognosis==
==Prognosis==
This is dependent on the WHO staging of the tumour. A stage I and II can expect a median survival time of 18 months whereas it is only 6 months for a stage III. Patients suitable for surgical excision has better prognosis than those treated medically.
This is related to the WHO stage of the tumour at diagnosis. An animal with a stage I and II neoplastic process could expect a median survival time of 18 months but this falls to only 6 months for an animal with stage III disease. Patients which undergo surgery to remove an insulinoma have a better prognosis than those treated medically but the condition will recur invariably after surgical removal. Those animals which show a recurrence of clinical signs after surgery may then be treated medically, an approach that produces a significant increase in median survival time (from approximately 2 years to 4 years).
==References==
==References==
*Polton GA, White RN, Brearley MJ, Eastwood JM (2007) '''Improved survival in a retrospective cohort of 28 dogs with insulinoma.''' ''J Small Anim Pract. 2007 Mar;48(3):151-6.''
*Ettinger, S.J. and Feldman, E. C. (2000) '''Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2''' (Fifth Edition) ''W.B. Saunders Company''.
*Ettinger, S.J. and Feldman, E. C. (2000) '''Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2''' (Fifth Edition) ''W.B. Saunders Company''.
*Fossum, T. W. et. al. (2007) '''Small Animal Surgery (Third Edition)''' ''Mosby Elsevier''
*Fossum, T. W. et. al. (2007) '''Small Animal Surgery (Third Edition)''' ''Mosby Elsevier''