Term
MDX of cow liver
Definition
Abscesses, hepatic, multifocal, (abscessation is chronic by definition, do not need to state), severe
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Term
MDX: Opened thoracic and abdominal cavities of a cougar
Definition
| Pneumonia, hematogenous, hemorrhagic, multifocal to coalescing, subacute, moderate to severe |
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Term
Pathogenesis: Opened thoracic and abdominal cavities of a cougar
Definition
Anything that could have led to septicemia. In this case, it was an open fracture in the left hindlimb resulting from a gunshot. Thus, a likely pathogenesis would be: gunshot --> open long bone fracture --> secondary bacterial osteomyelitis and cellulitis from environmental exposure --> entry of bacteria from the primary site into the blood stream, directly and/or via lymphatics --> hematogenous dissemination to lungs -->pulmonary infection leading to necrosis, inflammation, and hemorrhage.
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Term
MDX: opened thoracic and abdominal cavities (cougar 2)
Definition
| Pneumonia, hematogenous, hemmorhagic, multifocal, subacute, moderate to severe |
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Term
MDX: left lung, rabbit
Definition
| Bronchopneumonia, necrotizing, focally extensive, subacute, moderate |
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Term
MDX: Opened abomasum (stomach), mucosal surface, cow
Definition
Abomasitis (or gastritis), granulomatous, multifocal, moderate (granulomatous inflammation is chronic by definition).
Note the discreet nodules (granulomas). |
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Term
MDX: Small intestine, mesentery, and mesenteric lymph node (pig)
Definition
Enteritis, with hyperemia, diffuse, acute, severe, and lymphadenitis, diffuse, acute, moderate
Note how prominent (engorged) the mesenteric and serosal blood vessels are. Active hyperemia such as this most often indicates an acute inflammatory process in any tissue.
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Term
Etiology: Opened abomasum (stomach), mucosal surface, cow
Definition
| Ostertagia sp. (a nematode parasite). Lesion is pathognomonic! Know it! |
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Term
MDX: Liver (serosal surface), tiger
Definition
| Biliary cyst, focally extensive, chronic, moderate |
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Term
DDX: Liver (serosal surface), tiger
Definition
| Bile duct tumor (adenoma), abscess, granuloma. Because it has a dark greenish tinge (the color of bile), one can logically conclude its of biliary origin and therefore most likely a biliary cyst or bile duct adenoma at the gross level. It would ooze thick dark green fluid on section. |
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Term
Etiology:Mucosal surface of the small intestine, calf, H/E stain
Definition
Cryptosporidium parvum (a protozoan parasite that you can catch too).
Note the small circular basophilic organisms that appear to be extracellular and attached to the surface of mucosal epithelial cells. They are actually intracellular but maintain a superficial location in the cell (hence their incorrect designation as extracellular in the early literature, now corrected). |
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Term
MDX: Liver, foal. H/E stain.
Definition
Hepatitis, necrotizing, focal, acute, severe.
"Hepatic necrosis, focal, acute, severe" would also be an acceptable MDX since the inflammatory cell accumulation (-itis) is not yet that prominent. |
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Term
Silver stain
Definition
| Note the large filamentous "sheaves" of bacteria. These are Clostridium pilforme organisms (formerly known as Bacillus piliformis), the causative agent of Tyzzer's disease. Using this special stain, the bacteria appear as large colonies composed of thin filamentous forms that stain black. Note that erythrocytes also stain black with this special stain but they can be identified as such by their shape, size, and location (in sinusoids for the most part). |
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