Abstract
Image 1
D. Cardiovascular system
Systemic trematodiasis in freshwater turtles is most frequently caused by Spirorchiidae intravascular “blood flukes.” Gross lesions include hyperkeratosis of the plastron, hepatomegaly, and necrotic foci in multiple organs. Adult flukes reside in the heart and great vessels, where they produce eggs and occasionally induce intimal hyperplasia, vasculitis, and thrombi. Trematode eggs exit the circulation and elicit a granulomatous response in multiple organs including the liver (Image 1). Eggs escape from the vascular lumen, migrate into the intestinal lumen, and are shed in feces. Secondary bacterial infections are common. Confirmation of the diagnosis requires histopathology and identification of trematode eggs.
Additional Reading: Johnson CA, Griffith JW, Tenorio P, et al. Fatal trematodiasis in research turtles. Lab Anim Sci 1998;
Contributor: Kristen Hill-Thimmesch, Purdue University.
Image 2
B. Thyroid goiter
Thyroid goiter denotes hyperplastic enlargement of the thyroid gland, frequently in response to iodine deficiency, reflecting either direct dietary deficiency or goitrogen consumption. In this case, the lesion represents colloid goiter, the involution phase of hyperplastic goiter when iodine deficiency is reversed and there is a resulting reduction in follicular colloid endocytosis. Histologic hallmarks of colloid goiter include distension of the follicles with colloid and an attenuated thyroid epithelium (Image 2). Although the height of the follicular epithelium undergoes normal seasonal variation in snakes, and may affect ecdysis, thyroid follicle size is not expected to be altered in these instances.
Additional Reading: Topper MJ, Latimer KS, McManamon R, et al. Colloid goiter in an eastern diamondback rattlesnake (Crotalus adamanteus). Vet Pathol. 1994;
Contributor: Katherine Hughes, University of Cambridge, United Kingdom.
Image 3
A. Polycystic kidney disease
Goldfish with polycystic kidney disease have bilateral abdominal distension and the kidneys occupy most of the coelomic cavity. Microscopically, the cysts primarily arise from dilated glomerular capsules, in which atrophic glomeruli are occasionally present (Image 3). Gas bubble disease is a condition that results from fish breathing supersaturated water, which leads to gas emboli in multiple tissues. Grossly, bubbles are often visible lifting the epidermis and throughout the other organs. Coelomic lipomas comprise well-differentiated adipocytes without cyst formation. Cystic ovaries contain large amounts of fluid and are seen in close contact with normal ovaries.
Additional Reading: Munkittrick KR, Moccia RD, Leatherland JF. Polycystic kidney disease in goldfish (Carassius auratus) from Hamilton Harbour, Lake Ontario, Canada. Vet Pathol. 1985;
Contributor: Chelsea Hester, University of Tennessee
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D. Trophoblastic emboli
Trophoblastic emboli are an insignificant histological finding commonly seen in postparturient or pregnant chinchillas. Trophoblasts allow the embryo to invade the uterine epithelium in animals with hemochorial-type placentation. During this process, they can migrate through maternal vessels and be carried as emboli to several organs. Histologically, trophoblasts are polygonal cells with abundant amphophilic granular cytoplasm and large vesicular nuclei. The cells are commonly bi- or multinucleate. In the lung, the emboli expand the alveolar septal capillaries without an inflammatory response (Image 4). This postparturient chinchilla died from bacterial septicemia; the incidental trophoblastic emboli were seen only in the lung.
Additional Reading: La Perle KM, Green MG, Niewiesk S. Trophoblast deportation to the lungs of cotton rats (Sigmodon hispidus). Comp Med. 2014;
Contributor: Igor R. Santos, Universidade Federal do Rio Grande do Sul, Brazil.
Veterinary Pathology invites submission of exceptional gross or microscopic images for consideration as an Image Challenge, along with a multiple-choice question and answer. For details, see the Instructions to Authors on the journal website.