THE EFFECTS OF ROTATION ON THE RADIOGRAPHIC APPEARANCE OF THE CANINE CARDIAC SILHOUETTE IN DORSAL RECUMBENCY

Cardiac mensuration was done on thoracic radiographs of Beagles to determine the effects of rotation on the cardiac silhouette in dorsal recumbency. As the thorax became more rotated, surfaces of the heart not normally seen were projected, making interpretation of cardiac changes unreliable. A positioning standard based on the relationship of the dorsal spinous processes to the vertebral body was developed. If the tips of the dorsal spinous processes were within the bounds of the vertebral bodies, the radiographs were suitable for cardiac interpretation. If the tips of the dorsal spinous processes were outside the bounds of the vertebral bodies, there was enough rotation to make interpretation unreliable. A microcomputer, digitizer pad, and a BASIC language program were used to input, store, and calculate the various cardiac mensuration parameters.     

Histological Evaluation of Selected Organs of the Eurasian Beavers (Castor fiber) Inhabiting Poland

There is a general scarcity of data on the histological structure of major organs in the Eurasian beaver (Castor fiber). This study presents the histological characteristics of beaver organs such as the liver, spleen, cardiac muscle, lungs and kidneys. Tissue samples were collected from 21 beavers and analysed. Selected samples of tail tissue were additionally examined. Tissue samples were placed in neutral buffered formalin and embedded in paraffin. 4‐μm‐thick sections were stained with haematoxylin and eosin, and other staining techniques were also used. Scant amounts of inter‐lobular connective tissue were found in the liver. Ion or copper deposition was not observed, but scattered cytoplasmic glycogen deposits were present in hepatocytes. Our results suggest that beavers have defensive rather than storage spleens. Interestingly, the presence of melanin in splenic red pulp was noted. The histological structure of the examined organs closely resembled that of other rodent species. According to our knowledge, this is the first study evaluating the histological structure of beaver organs. Nevertheless, precise characterization of the evaluated organs requires further work with the involvement of accurate and reliable techniques, such as molecular biology or electron microscopy methods.     

Interventional cardiology for the criticalist

Objective – To review indications, procedures, and prognosis for common cardiovascular emergencies requiring intervention in small animals. Etiology – Pericardial effusion, symptomatic bradycardia, and heartworm‐induced caval syndrome are examples of clinical scenarios commonly requiring intervention. Pericardial effusion in small animals occurs most frequently from cardiac neoplasia, idiopathic pericarditis, or congestive heart failure. Indications for temporary pacing include transient bradyarrhythmias, ingestions resulting in chronotropic incompetence, and emergency stabilization of critical bradyarrhythmias. Caval syndrome results from a large dirofilarial worm burden, pulmonary hypertension, and mechanical obstruction of right‐sided cardiac output with resultant hemolysis and organ dysfunction. Diagnosis – The diagnosis of pericardial effusion is suspected from signalment and physical findings and confirmed with cardiac ultrasound. Symptomatic bradycardias often present for syncope and definitive diagnosis derives from an ECG. Caval syndrome is diagnosed upon clinical, hematologic, and ultrasonographic evidence of severe heartworm infestation, cardiovascular compromise, and/or mechanical hemolysis. Therapy – Pericardial effusion is alleviated by pericardiocentesis in the emergency setting, though may require further intervention for long‐term palliation. Temporary transvenous pacing can be performed emergently to stabilize the symptomatic patient with a bradyarrhythmia. Dirofilariasis leading to caval syndrome requires urgent heartworm extraction. Prognosis – The prognosis for pericardial effusion is dependent upon the underlying etiology; the prognosis for cardiac pacing is favorable, and the prognosis for caval syndrome is grave if untreated and guarded to fair if heartworm extraction is performed.     

RADIOGRAPHIC AND ULTRASONOGRAPHIC EVALUATION OF EGG RETENTION AND PERITONITIS IN TWO GREEN IGUANAS (IGUANA IGUANA)

The radiographic technique and radiographic and sonographic findings in two green iguanas with egg retention and peritonitis are described. Neither radiography nor ultrasound provided for identification of free eggs within the coelomic structure secondary to presumed oviduct rupture. Gravidity and coelomic effusion were confirmed by both radiography and ultrasound. Radiography and ultrasound are valuable tools in the diagnosis of egg retention and peritonitis in the green iguana.     

Gradual Occlusion of Extrahepatic Portosystemic Shunts in Dogs and Cats Using the Ameroid Constrictor

Gradual occlusion of the splenic vein, using a specialized device (ameroid constrictor), was evaluated experimentally in three normal beagle dogs. Splenoportograms were used to verify that total occlusion of the splenic vein had occurred in all dogs within 4 to 5 weeks after application of the device. The ameroid constrictor (AC) was also evaluated as a method of gradual vascular occlusion in 12 dogs and two cats with single, extrahepatic, portosystemic shunts (PSS). Serum bile acid (SBA) concentrations were measured and portal scintigraphy (PS) was performed on all 14 animals preoperatively and 10, 20, 30, and 60 days postoperatively. Two dogs (14%) died from portal hypertension in the early postoperative period. One dog and one cat developed multiple acquired PSS, confirmed by mesenteric portography 90 days after the operation. Portal scintigraphy confirmed total occlusion of the primary shunt in the other 10 animals. Shunt fractions (SF), as measured by PS on postoperative days 30 and 60, declined significantly from preoperative values. Significant decreases were noted between preoperative and postoperative values for preprandial SBA on postoperative day 60 and for postprandial SBA on postoperative day 30. SBA concentrations did not correlate with SF. Based on this study, gradual vascular occlusion using the AC is recommended as a method for treatment of single, extrahepatic, PSS.