Endocrinology, An Issue of Veterinary Clinics: Exotic Animal Practice (eBook)
100 Seiten
Elsevier Health Sciences (Verlag)
978-0-323-26419-8 (ISBN)
This issue will explore the latest research and clinical information concerning endocrinology of exotic pet species. The articles will cover thyroid disease in rodent species, deslorelin implants in birds, pathology of the avian panceas, non-surgical management of ferret adrenal endocrinopathy, medical management of reproductive disorders in birds, neuroendocrine regulation of calcium metabolism in reptiles, clinical aspects of the avian hypothalamic/pituitary axis, and more!
Lesions of the Avian Pancreas
Robert E. Schmidt, DVM, PhD, DACVP∗rschmidt@zooexotic.com and Drury R. Reavill, DVM, DABVP (Avian Practice), DACVP, Zoo/Exotic Pathology Service, 7647 Wachtel Way, Citrus Heights, CA 95610, USA
∗Corresponding author.
Although not well described, occasional reports of avian exocrine and endocrine pancreatic disease are available. This article describes the lesions associated with common diseases of the avian pancreas reported in the literature and/or seen by the authors.
Keywords
Avian pancreas
Exocrine
Endocrine
Pathology
Infectious disease
Noninfectious disease
Proliferative disease
Key points
• Disease can affect both exocrine and endocrine pancreas.
• Pancreatic disease can be infectious, non-infectious or proliferative.
• Reports of pancreatic disease in birds are scattered in the literature.
Diseases of the pancreas can affect the exocrine pancreas, the endocrine pancreas, or both. Diseases and lesions of these tissues are infrequently described in birds. This article describes the diseases/lesions of both the exocrine and endocrine pancreas in the general categories of noninfectious, infectious, and neoplastic/proliferative conditions.
Exocrine pancreas noninfectious disease
Prolonged caloric deficiency in birds will lead to pancreatic atrophy.1 Grossly, the change may not be significant; but histologically, there is acinar epithelial atrophy associated with normal islets of Langerhans. Atrophy can also be the end result of a variety of problems, including the following:
• Congenital disease2
• Chronic inflammation, which in turn can be caused by infection or immune-mediated disease
• Damage from toxins, such as zinc3
• Problems with proper blood flow to the pancreas as with arthrosclerosis in susceptible birds
The degree of pancreatic atrophy can vary but is characterized grossly by a small and possibly irregular pancreas and histologically by a variable loss of zymogen granules, with shrinkage of acinar cells. The cells usually have clear cytoplasm. Acini are irregular, and acinar lumens may be difficult to see (Fig. 1). Atrophy has been described in several species.3,4
Fig. 1 Pancreatic atrophy. There is almost complete loss of zymogen and acinar cells are small with clear cytoplasm (H&E, 70×).
The pancreas is the target organ in cases of zinc toxicity.5 Gross lesions may not be noticeable. However, slight parenchymal mottling is occasionally seen; in chronic disease, the pancreas is atrophied. Acutely, the primary microscopic lesion is vacuolation and degranulation of acinar cells (Fig. 2). Necrosis of individual cells may also be present. Minimal mononuclear inflammatory infiltrates may be seen. In chronic disease, the appearance is similar to that described earlier, with the potential addition of interstitial fibrosis.
Fig. 2 Severe vacuolar degeneration of pancreatic exocrine cells attributed to zinc toxicity (H&E, 28×).
Rarely other toxicities have involved the pancreas. Levamisole toxicity in kiwis (Apteryx mantelli) resulted in acute pancreatic degeneration and necrosis, among other lesions in the lungs and liver. It was thought that kiwis are sensitive to the drug.6
Acute pancreatic necrosis is seen in psittacine birds, particularly Quaker parakeets.7 Many of these birds die suddenly. Gross lesions include a firm pale pancreas, variable hemorrhage, and adjacent fat necrosis characterized by firm yellow-white foci (Fig. 3). In one cockatoo, a marked serous and serosanguineous effusion was reported. Histologic changes are caused by acute coagulation necrosis of pancreatic acini, hemorrhage within the pancreatic lobules, and multifocal necrosis of mesenteric adipose tissue (Fig. 4). One of the causes of the lesions may be a high-fat diet, but the exact cause has not been determined.
Fig. 3 Acute pancreatic necrosis in a Quaker parakeet.
Fig. 4 Microscopic appearance of acute pancreatic necrosis. There is severe coagulative necrosis of the pancreas (left) adjacent to the small intestine (H&E, 70×).
Fat accumulation in the pancreatic acinar cells sometimes accompanies severe fatty liver disease, as is sometimes seen in Amazon parrots. This change is usually not grossly visible.
Pancreatic fibrosis of undetermined cause is also seen infrequently. Grossly, the pancreas is firm and irregular; microscopically, interstitial fibrosis replaces normal acini (Fig. 5).8
Fig. 5 Severe chronic pancreatic fibrosis. Remaining acinar are small and separated by fibrous connective tissue (H&E, 70×).
Infectious disease
Viral and bacterial agents reported to cause pancreatitis include the following:
• Herpesvirus
• Polyomavirus
• Adenovirus
• Paramyxovirus
• Avian influenza A
• Poxvirus, West Nile virus
• A variety of gram-negative bacteria
Paramyxovirus can cause chronic pancreatitis, particularly in Neophema sp and small passerine birds. Affected pancreases are firm and irregular. A variable lymphoplasmacytic and histiocytic inflammatory response and lymphoid follicle formation characterize the lesion (Fig. 6). Fibrosis is seen in some cases.
Fig. 6 Chronic lymphocytic pancreatitis associated with paramyxovirus-3 infection.
Herpesvirus,15 polyomavirus, poxvirus, and adenovirus usually induce pancreatic necrosis and variable inflammation as part of a systemic disease process. Etiologic specificity is determined by finding characteristic intranuclear inclusion bodies (Figs. 7 and 8).
Fig. 7 Herpesvirus-induced pancreatic necrosis and characteristic intranuclear inclusion bodies (arrows) (H&E, 280×).
Fig. 8 Poxvirus infection of the pancreas resulting in swollen acinar cells containing eosinophilic inclusion bodies (H&E, 70×).
Influenza A virus causes pancreatic lesions in both experimental and natural disease.16–18 Grossly, the pancreas is hemorrhagic and necrotic; acute necrosis is seen histologically.16
Several bacterial agents have been associated with pancreatitis.15
Gross lesions vary from none to hemorrhage and necrosis, and there may be a purulent exudate in cases of bacterial pancreatitis. Bacterial infection is histologically characterized by necrosis, fibrin deposition, and a primarily heterophilic response, whereas infection with Chlamydophila psittaci results in a nonsuppurative pancreatitis. The pancreas can also be involved in cases of systemic mycobacteriosis, although infrequently.19
Parasitic pancreatitis can follow the plugging of pancreatic ducts by nematodes or trematodes.2,20 Grossly, pancreatic ducts are thickened and prominent; the pancreas has a roughened appearance (Fig. 9). Trematodiasis may result in be brown-black pigmentation. Histologically, the pancreatic ducts are dilated and contain the parasites in the duct. Inflammatory changes are minimal to mild. Pancreatic trematodiasis is seen almost exclusively in Amboina king parrots.
Fig. 9 Pancreatic fluke infestation in a king parrot. Note atrophy and generalized roughening of the pancreas.
Cryptosporidiosis of the pancreatic ducts has been reported in ostriches.21 Grossly, the birds were emaciated and had atrophic-appearing pancreases. Microscopically, the organisms were present associated with ductal epithelium.
There was some necrosis and lymphoplasmacytic inflammation.
Proliferative and neoplastic disease
Bile and pancreatic duct hyperplasia and papilloma formation is seen in some birds with internal papillomatosis (PsHV 3).22 They may accompany bile and pancreatic duct changes or occur independently of them.
Pancreatic ductular neoplasia may also be associated with PsHV 3.23,24 Morphologically, low-grade papillary adenocarcinoma is occasionally seen. These tumors are composed of moderately undifferentiated cells within acinarlike...
Erscheint lt. Verlag | 9.2.2014 |
---|---|
Sprache | englisch |
Themenwelt | Medizin / Pharmazie |
Veterinärmedizin ► Klinische Fächer ► Chirurgie | |
Veterinärmedizin ► Kleintier | |
ISBN-10 | 0-323-26419-0 / 0323264190 |
ISBN-13 | 978-0-323-26419-8 / 9780323264198 |
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