CONTRAST‐ENHANCED MAGNETIC RESONANCE ANGIOGRAPHY FOR DIAGNOSIS OF PORTOSYSTEMIC SHUNTS IN 10 DOGS

Computed tomography angiography, sonography, scintigraphy, and portography can be used to evaluate the portal vasculature to evaluate for a portosystemic shunt (PSS). Time‐of‐flight magnetic resonance angiography (TOF‐MRA) and contrast‐enhanced MRA (CE‐MRA) are other potentially useful techniques. The aim of this study was to evaluate CE‐MRA in 10 dogs suspected of having a PSS. Noncontrast MR images of the abdomen were obtained using a Siemens Symphony MR‐scanner (1.5 T) and a T1‐weighted FLASH‐3D sequence with a very short scan time (about 20 s). After injection of contrast medium, the initial sequence was repeated five times. The sequence with the best contrast medium filling of the portal vasculature was selected subjectively, subtracted from the initial survey image series, and a maximum intensity projection (MIP) of the subtraction data, in multiple views, was created. The cross‐sectional and MIP images were evaluated for abnormal portosystemic vasculature. A single PSS was identified and confirmed at surgery in all dogs. A portocaval shunt was found in five dogs, a portophrenic shunt in three dogs, a portoazygos shunt in one, and a central divisional intrahepatic shunt in one other dog. Based on our results, CE‐MRA is a useful tool for imaging abdominal and portal vasculature and for the diagnosis of a PSS.     

Changes in Cardiopulmonary Variables and Platelet Count During Anesthesia for Total Hip Replacement in Dogs

Changes in cardiopulmonary function and platelet count were determined in 22 dogs of various breeds that underwent total hip replacement with cemented femoral prostheses. In 11 dogs (group I) polymethylmethacrylate (PMMA) was inserted without venting the reamed and lavaged femoral canal. In a second group of 11 dogs (group II) a urethral catheter (ID: approximately 2.7 mm) was placed into the medullary cavity before the insertion of PMMA. The application of PMMA resulted in a decrease in end-tidal carbon dioxide tension (PETco₂) until 5 minutes after insertion of bone cement. Increases in arterial to end-tidal pCO₂ gradient [P(a-ET)co₂] and physiological dead space (V_D/V_T) were recorded between 2 minutes before and 5 minutes after insertion of PMMA in 12 dogs. A significant decrease in platelet count occurred in both groups of dogs. Decreases in arterial pO₂ (Pao₂), arterial/alveolar oxygen tension ratio (Pao₂/PAo₂), and percent O₂ saturation of hemoglobin in arterial blood (Sao₂) were not statistically significant. No significant differences could be detected between data obtained from both groups of dogs. An increase in femoral intramedullary pressure caused by the insertion of PMMA and subsequent pulmonary microembolism by medullary contents has been considered the most likely cause for changes in pulmonary function. The lack of statistically significant differences in cardiopulmonary variables and platelet count between the two groups of dogs could have been related to inefficient pressure reduction by the method used.     

RADIATION THERAPY COMMUNICATION: EQUINE HEMANGIOMA

A 13-month-old Standardbred Colt had a recurrent hemangioma at the level of the coronary band. Multiple excisions had led to a nonhealing skin and hoof defect. Using 14 MV electrons, a total dose of 36 Gy was administered, given as six fractions of 6 Gy twice a week. Wound healing by second intention was achieved over the next 4 months and the colt began race training 6 months after the end of therapy. Twenty months later the colt is sound and there is no evidence of tumor recurrence.