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*[[Adenoma|Adenomas]] and [[Carcinoma|carcinomas]] deerived from beta cells
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*Respond rapidly to iv glucose
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*Can be identified by immunocytochemical means
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*Dogs 5-12 years of age most commonly affected
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*Older cattle, associated with periodic convulsions
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====Clinical signs====
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*Hyperinsulinism
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*Hypoglycaemia - often episodic
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**Neurologic signs - stupor, confusion, coma, seizures, peripheral neuropathy may also develop
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==Description==
 
==Description==
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==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.   
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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==
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*'''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
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===Histopathology===
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===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
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*Pancreatic beta cells can readily be identified using immunocytochemistry
    
===Diagnostic Imaging===
 
===Diagnostic Imaging===
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==Treatment==
 
==Treatment==
 
===Emergency Stabilisation===
 
===Emergency Stabilisation===
*In the event of a hypoglycaemic episode, a dextrose bolus should be given immdediately.
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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.
*This should be followed by intravenous fluid therapy with 2.5% dextrose.
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*Alternatively, if the patient is able to eat, frequent feedings can be used instead of dextrose fluid therapy.  This may be preferred to avoid the risk of rebound hypoglycaemia.
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===Medical===
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===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.
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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.
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*[[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.
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*'''Diazoxide''', an oral hyperglycaemic drug, used to inhibit pancreatic insulin secretion and tissue glucose uptake.
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*'''Octreotide''', a somatostatin analogue which reduces the synthesis of insulin, is rarely used for management of insulinomas.
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===Surgery===
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===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:
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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
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*'''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
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*[[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
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*'''Epilepsy''' and '''diffuse polyneuropathy''' due to chronic hypoglycaemia.
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*'''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.
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This is related to the WHO stage of the tumour at diagnosisAn 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==
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*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''
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