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*Characterised by
==Introduction==
**Hyperglycaemia
Glucagonomas are very rare tumours of the alpha cells of the pancreatic islets of Langerhans that produce the hormone glucagon without appropriate regulation. The excessive secretion of glucogon is a form of topic paraneoplastic syndrome. The disease has been reported in approximately ten dogs and it is therefore extremely rare.
**Vacuolar hepatopathy
As in humans, glucagonoma is characterised by the formation of skin lesions collectively described as [[Hepatocutaneous Syndrome|'''necrolytic migratory erythema''' (NME)]]<ref>Byrne KP. '''Metabolic epidermal necrosis-hepatocutaneous syndrome.''' ''Vet Clin North Am Small Anim Pract. 1999 Nov;29(6):1337-55.''</ref>, a syndrome which is observed much more commonly in dogs with liver failure when it is termed [[Endocrine effects on the skin - Pathology#Superficial Necrolytic Dermatopathy|'''hepataocutaneous syndrome''']]. Glucagonoma accounts for approximately ten percent of cases of NME. Dogs with glucagonoma frequently show signs of [[Diabetes Mellitus|diabetes mellitus]] as glucagon is antagonistic to insulin.
==Signalment==
Glucagonoma has only ever been described in dogs and humans.
==Diagnosis==
===Clinical Signs===
Affected animals develop cutaneous signs of NME, comprising '''erosive, crusting lesions''' of:
*The feet and digital pads are the most common location
*The external genitalia
*The muco-cutaneous junctions of the mouth and eyes
*The distal extremities and other pressure points (elbows, hocks and ventral abdomen)
*The pinnae
Other clinical signs observed in dogs with glucagonoma are non-specific and include '''lethargy''', '''anorexia''', '''weight loss''' and '''lymphadenopathy'''.
===Laboratory Tests===
Affected animals often develop '''hyperglycaemia''' due to the effects of glucagon and it may be difficult to differentiate the disease from simple diabetes mellitus. Glycosuria may also be detected.
Excessive concentrations of glucagon are thought to increase the rate at which amino acids are converted to urea in the liver, reducing the '''plasma concentrations of amino acids'''.
Other reported changes on analysis of blood samples include increased ALP and ALT, decreased albumin and globulin and decreased blood urea concentrations.
In humans, '''serum glucagon concentration''' is measured to diagnose glucagonoma and this has also been reported in dogs.
===Pathology===
A definitive diagnosis is made by performing '''immunohistochemistry''' on pancreatic biopsy samples to detect an expanded population of glucagon-secreting alpha cells. The tumours are often large at the time of diagnosis (>5 centimetres in diameter) and they frequently metastasise to the liver or local lymph nodes. Vacuolar hepatopathy may be observed on histopathological analysis of liver biopsies.
==Treatment==
'''Surgical excision''' is the treatment of choice, even though the tumour will often have metastasised by the time it is diagnosed. In cases that are amenable to resection, medical treatment may be attempted with subcutaneous injections of the somatostatin analogue '''octreotide'''<ref>Oberkirchner U, Linder KE, Zadrozny L, Olivry T. '''Successful treatment of canine necrolytic migratory erythema (superficial necrolytic dermatitis) due to metastatic glucagonoma with octreotide.''' ''Vet Dermatol. 2010 May 24''</ref>.
Animals with severe cutaneous lesions may benefit from supplementation with essential fatty acids and zinc.
==Prognosis==
The prognosis is generally poor as the tumour has usually metastasised by the time it is diagnosed.
{{Learning
|literature search = [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=Glucagonoma&occuring1=title&rowId=2&options2=AND&q2=&occuring2=freetext&rowId=3&options3=AND&q3=&occuring3=freetext&x=76&y=6&publishedstart=yyyy&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all Glucagonoma publications]
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==References==
<references/>
Ettinger, S.J, Feldman, E.C. (2005) '''Textbook of Veterinary Internal Medicine (6th edition, volume 2)''' ''Elsevier Saunders''
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[[Category:Pancreas_-_Hyperplastic_and_Neoplastic_Pathology]][[Category:Endocrine_System_-_Pathology]]
[[Category:Neoplasia]]
[[Category:Pancreatic Diseases - Dog]][[Category:Endocrine Diseases - Dog]]
[[Category:Expert_Review]]