Racing performance following the laryngeal tie-forward procedure: a case-controlled study.

REASONS FOR PERFORMING STUDY: The laryngeal tie-forward procedure (LTFP) is becoming widely used for correction of dorsal displacement of the soft palate (DDSP) despite the absence of an evidence-based assessment of its efficacy. HYPOTHESES: The LTFP returns racing performance to preoperative baseline levels and to that of matched controls; and post operative laryngohyoid position is associated with post operative performance. DESIGN AND POPULATION: Case-controlled study of racehorses undergoing a LTFP for dorsal displacement of the soft palate at Cornell University between October 2002 and June 2007. METHODS: The presence of at least one post operative start and race earnings ($) were used as outcome variables. Controls were matched by age, breed and sex from the third race prior to surgery. A novel radiographic reference system was used to determine laryngohyoid position pre- and post operatively. Data for definitively and presumptively diagnosed cases were analysed separately. RESULTS: During the study interval, 263 racehorses presented, of which 106 were included in the study; 36 had a definitive diagnosis of DDSP and 70 a presumptive diagnosis. Treated horses were equally likely to race post operatively as controls in the equivalent race. Treated horses had significantly lower earnings in the race before surgery than matched controls. The procedure moved the basihyoid bone dorsally and caudally and the larynx dorsally and rostrally. A more dorsal post operative basihyoid position and more dorsal and less rostral laryngeal position were associated with an increased probability of racing post operatively. CONCLUSIONS: Horses undergoing a LTFP are as likely to race post operatively as matched controls. The procedure restores race earnings to preoperative baseline levels and to those of matched controls. POTENTIAL RELEVANCE: This study provides strong evidence supporting the use of the LTFP in racehorses. Further work is needed to determine the relationship between laryngohyoid conformation and nasopharyngeal stability in horses.

Feasibility of fractionating MAG3 cold kit for cost reduction.

99Tcm-MAG3 is the first 99Tcm-labelled radiopharmaceutical with a renal clearance similar to that of 131I-OIH. The cost of a unit dose of 99Tcm-MAG3 is comparatively less expensive than the cost of a combined 99Tcm-DTPA and 131I-OIH study dose. However, this cost-saving is dramatically reduced when only a few doses are withdrawn from a 99Tcm-MAG3 kit. Our goal in this study was to subdivide the MAG3 kit into fractions to reduce expense. By dissolving the lyophilized ingredients of MAG3 kits with either 5 or 10 ml N2-purged normal saline, the resultant liquid was divided into 1-ml aliquot vials filled with N2. The MAG3 aliquot vials were then frozen at -70 degrees C for future use. The radiochemical purity (RCP) of each vial was evaluated using the recommended Sep-Pak C18 column chromatography at different time periods. Over the entire 28-day evaluation period, the average RCP of the 5:1 dilution MAG3 vials after reconstitution with 3.7 GBq 99Tcm was maintained at 95.6 +/- 2.7% (n = 100) for 6 h, whereas the 10:1 fractionation MAG3 kits after labelling with 740 MBq 99Tcm showed an average RCP value of 98.4 +/- 2.1% (n = 100) for 6 h. Based upon these results, it is concluded that the fractionation of MAG3 kits and frozen storage in an N2 atmosphere not only maintains the stability of MAG3 but also provides a cost-effective method for using 99Tcm-MAG3.