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Three cases of carcinoid tumor in horses are described. The tumors originated from the maxillary sinuses and the retrobulbar region and caused exophthalmos. Histologically, they had a characteristic endocrine pattern and were argyrophilic with the Grimelius stain. All tumors contained reactivity for neuron-specific enolase and synaptophysin. Two of three tumors were reactive for both bovine and porcine chromogranin A. These immunohistochemical results confirm the neuroendocrine nature of these tumors. Neuroendocrine cells could not be detected in the nasal mucosa and maxillary sinuses of a normal horse; therefore, the origin of these carcinoid tumors remains obscure.

Contrast radiography provides a clear survey of the size, shape, and location of extratendovaginal fluid-filled cavities, distended bursa, and tendon sheaths and demonstrates intersynovial communication. Ultrasonography effectively demonstrates Achilles tendon injury, slippage of the SDFT off the summit of the calcaneus, assorted ligamentous injuries, and cystic or solid extratendovaginal masses. It will also demonstrate distended bursae and tendon sheaths, but it is not as effective in demonstrating a synovial herniation, or a narrow synovial fistula. Contrast radiography may prove to be the imaging modality of choice for examination of fluctuating swellings, whereas ultrasonography is preferred for the assessment of firm swellings. Routine radiographic evaluation in the clinical assessment of soft tissue injuries in the hock region continues to play an invaluable diagnostic role.

Nine calves between three and 18 weeks old with serologically confirmed natural bovine respiratory syncytial virus infection were examined clinically, radiographically and by radionuclide lung perfusion imaging. The results were compared with those from seven healthy calves. The diseased calves were euthanased and examined pathologically, virologically and bacteriologically. The clinical signs indicated that the disease was in an acute stage. Radiography of the diseased animals revealed cysts, corresponding morphologically with bullous emphysema, and infiltrations roughly corresponding in distribution with atelectatic and, or, pneumonic areas. Radionuclide lung perfusion imaging revealed no perfusion shifts between the left and right lungs and a normal perfusion pattern in five of the nine diseased calves. The abnormalities in the perfusion patterns of three calves were probably caused by anatomical disorders such as cysts and pleural adhesions, but no cause of the abnormality could be found in one calf. These findings suggest that in calves infected with bovine respiratory syncytial virus, the normal perfusion pattern is maintained until anatomical disorders occur. The pathological examination and radiography revealed that the cranioventral lung fields were particularly poorly ventilated. This finding and the normal perfusion pattern indicate that these parts of the lungs are probably the sites where shuntings and perfusion-ventilation mismatchings occur.

Cholesterinic granulomas are tumor-like masses in the choroid plexuses of horses. This report describes the computed tomographic findings in four horses with cholesterinic granulomas, including the clinical and the pathologic features. All four horses had bilateral cholesterinic granulomas in the lateral ventricles. Computed tomographic images clearly delineated the masses, the opacity of the granulomas, and the enhancement pattern after intravenous bolus injection of contrast medium; these factors varied considerably. Additional CT findings were symmetric or asymmetric widening of the lateral ventricles.

To obtain radiographic information concerning the equine stomach, a gastrographic contrast examination is required. This study describes this procedure in detail. A powerful radiographic unit, the tubehead linked to an image intensifier and suspended by an electromechanical overhead gantry system, is required. To obtain accurately positioned radiographs during the fluoroscopic examination, a cassette holder with a stationary grid is mounted at the entrance window of the image intensifier. The examination is performed in the unsedated standing horse after 24 hours of starvation, using a combination of survey radiography and fluoroscopic viewing after the inflation of air, followed by the administration of barium sulphate suspension by stomach tube. The gastrographic contrast examination is performed in three experimental animals and 23 abnormal horses. Pneumogastrophy appeared to be valuable to diagnose gastric tumors, to differentiate between gastric tumors and other masses in the cranial abdomen, and to visualize gastric parasites, even in large horses. The use of barium sulphate suspension does not result in an adequate double contrast of the stomach, but it may aid to diagnose esophagogastric or pyloric stenosis and gastric or duodenal ulcers.