Page 607 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 26 Tumors of the Endocrine System 585

Gastrinomas typically are reported in middle-aged dogs and been reported. 466,470 The tumors sometimes can be detected on
older cats. 442,443 No obvious breed or sex predilections have been abdominal ultrasound examination or CT. 443,466,469,471 Plasma
glucagon concentrations have been measured in some cases, and
identified. Clinical signs result from gastric acid hypersecretion
VetBooks.ir and gastric mucosal hyperplasia. The most common signs are amino acid concentrations also have been evaluated in a small
number of patients,
vomiting and weight loss. Melena, abdominal pain, anorexia,
468–470,472
but the sensitivity and specificity of
regurgitation, hematemesis, hematochezia, and diarrhea also these diagnostic tests have not been evaluated. Surgical resection
may occur. 441–443,445,447–454 Physical examination findings range or debulking is the treatment of choice for canine glucagonoma.
from unremarkable to a patient in hypovolemic shock because Rare reports exist of the use of somatostatin analogs. 470,471 The
of perforation of an ulcer. A serum biochemistry profile, CBC, dermatologic lesions of NME may improve after surgery or medi-
and urinalysis may demonstrate changes associated with protein cal therapy, 471,472 but metastasis is common at the time of diag-
loss and bleeding resulting from GI ulceration or may reflect the nosis and the prognosis is generally poor. 461,469 When NME is
consequences of severe or persistent vomiting or the presence suspected, it is important to rule out liver disease, a more common
of hepatic metastases. One case of common bile duct obstruc- cause of this dermatologic condition in dogs.
tion caused by a duodenal gastrinoma has been reported in a
dog. 444 Abdominal radiographs often are unremarkable unless Intestinal Carcinoid
GI perforation has occurred. Contrast radiographs and abdomi-
nal ultrasound examination may show evidence of GI ulceration Intestinal carcinoid tumors are rare in dogs and cats. They arise
and a thickened pyloric antrum and gastric wall. Ultrasound from neuroendocrine cells that are found in a variety of locations,
examination also may reveal metastatic lesions in the liver or including the GI tract, liver, gallbladder, and pancreas. 443,473–478
regional lymph nodes; however, the primary tumor in the pan- Clinical signs generally are associated with the anatomic location
creas usually is too small to be detected with this modality. 447 of the tumor, although the physiologic effects of vasoactive sub-
The results of techniques such as CT and MRI have not been stances released from the tumor were suspected to be the cause of
widely reported in dogs and cats with gastrinomas. Endoscopy clinical signs in one dog with an intestinal carcinoid. 477 In general,
may reveal esophagitis, with ulceration, gastric and duodenal the prognosis for these tumors is guarded because metastasis is
ulceration, thickened gastric rugae, and hypertrophy of the common at the time of diagnosis. 443 Surgical removal is recom-
pyloric antrum. The diagnosis may be supported by measuring mended; a single case report has described adjuvant chemotherapy
basal serum gastrin levels or levels after provocative testing or in a dog. 479
by scintigraphy using radiolabeled pentetreotide. 455 Basal gas-
trin levels have been significantly increased in dogs and cats with References
gastrinoma; however, gastrin levels also can be increased in renal
or gastric disease, and no specific cutoff values for diagnosis have 1. Polledo L, Grinwis GCM, Graham P, et al.: Pathological findings
been determined. 443,456 Although it has been suggested that in the pituitary glands of dogs and cats, Vet Pathol 55:880–888,
treatment with medications such as proton pump inhibitors and 2018.
H -antihistamines can lead to increased serum gastrin concen- 2. Owen TJ, Martin LG, Chen AV: Transsphenoidal surgery for pitu-
2
trations, recent studies indicate that these effects are mild and itary tumors and other sellar masses, Vet Clin North Am Small Anim
short-lived and may not in fact inhibit the diagnosis of gastri- Pract 48:129–151, 2018.
noma. 457–460 Provocative testing to diagnose gastrinoma rarely 3. Pollard RE, Reilly CM, Uerling MR, et al.: Cross-sectional imag-
has been reported in veterinary medicine. 442,443,461 ing characteristics of pituitary adenomas, invasive adenomas and
Exploratory laparotomy is recommended for dogs and cats with adenocarcinomas in dogs: 33 cases (1988-2006), J Vet Intern Med
24:160–165, 2010.
a suspected gastrinoma. Even though most dogs and cats have vis- 4. Moore SA, O’Brien DP: Canine pituitary macrotumors, Compend
ible metastasis at the time of initial diagnosis, surgical debulking Contin Educ Vet 30:33–41, 2008.
reduces the gastrin secretory capacity and enhances the efficacy 5. Kent MS, Bommarito D, Feldman E, et al.: Survival, neurologic
of medical therapy. 462 In addition, deep or perforated GI ulcers response, and prognostic factors in dogs with pituitary masses
can be identified and excised. Long-term medical management treated with radiation therapy and untreated dogs, J Vet Intern Med
-antihistamines, 21:1027–1033, 2007.
includes the use of proton pump inhibitors, H 2
and sucralfate. 448,452 Octreotide has been used in three dogs with 6. Wood FD, Pollard RE, Uerling MR, et al.: Diagnostic imaging
success. 455,463,464 STs for dogs and cats with gastrinoma range findings and endocrine test results in dogs with pituitary-dependent
from 1 week to 26 months. 442,462,465 hyperadrenocorticism that did or did not have neurologic abnor-
malities: 157 cases (1989-2005), J Am Vet Med Assoc 231:1081–
1085, 2007.
Glucagonoma 7. Schmid S, Hodshon A, Olin S, et al.: Pituitary macrotumor caus-
ing narcolepsy-cataplexy in a Dachshund, J Vet Intern Med 31:545–
Glucagonomas are rare in dogs, and currently only a single pub- 549, 2017.
lished case report exists in a cat. 443,466 These tumors are associated 8. Goossens MM, Rijnberk A, Mol JA, et al.: Central diabetes insipi-
with a crusting dermatologic condition termed necrolytic migra- dus in a dog with a pro-opiomelanocortin-producing pituitary
tory erythema (NME). Other associated problems include hyper- tumor not causing hyperadrenocorticism, J Vet Intern Med 9:361–
glycemia or overt diabetes mellitus, hypoaminoacidemia, and 365, 1995.
increased liver enzyme activity. Skin lesions associated with NME 9. Behrend EN: Canine hyperadrenocorticism. In Feldman EC, Nel-
include hyperkeratosis, crusting, and ulceration and erosions of son RW, Reusch CE, et al. editors: Canine and feline endocrinology,
the footpads, mucocutaneous junctions, external genitalia, dis- ed 4., St. Louis, 2015, Elsevier, pp 377–451.
tal extremities, pressure points, and ventral abdomen. 461,466–471 10. Perez-Alenza D, Melian C: Hyperadrenocorticism in dogs. In
Ettinger SJ, Feldman EC, Cote E, editors: Textbook of veterinary
Glucagonomas usually arise from alpha cells in the pancreas; internal medicine, ed 8, St. Louis, 2017, Elsevier, pp 1795–1811.
however, extrapancreatic glucagon-secreting tumors also have