A randomised, controlled trial to determine the effect of levothyroxine on Standardbred racehorses
| Autor: | Laurent L. Couëtil, Carla Olave, Janice E. Kritchevsky, Stacy H. Tinkler, K.M. Ivester, Melissa Tropf, Lauren Forsythe |
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| Rok vydání: | 2021 |
| Předmět: |
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Levothyroxine Reference range Placebo Heart Rate Physical Conditioning Animal Post-hoc analysis Heart rate Atrial Fibrillation Medicine Animals Horses Lactic Acid Treadmill education education.field_of_study business.industry Atrial fibrillation General Medicine medicine.disease Thyroxine Anesthesia Exercise Test Horse Diseases business medicine.drug |
| Zdroj: | Equine veterinary journalREFERENCES. 54(3) |
| ISSN: | 2042-3306 |
| Popis: | BACKGROUND The use of thyroid supplement is pervasive in athletic horses although its effects on measures of performance are not known. OBJECTIVES One purpose of this study was to determine whether supra-physiologic doses of levothyroxine affect the velocities at which blood lactate was greater than 4 mmol/L (VLa4 ) and heart rate was over 150 (V150 ) and 200 (V200 ) beats per minute respectively. Additionally, a survey of post-race blood samples was also conducted to determine whether high thyroxine concentrations were common in racehorses. STUDY DESIGN A randomised, crossover, trial was performed in six healthy Standardbred racehorses. METHODS Study 1: T4 was determined in 50 post-race samples from a single Standardbred meet. Study 2: Research horses were trained to fitness and then randomised to one of three treatments: carrier, 0.1 mg/kg thyroxine or 0.25 mg/kg thyroxine for 2 weeks. Horses completed a standardised exercise treadmill test (SET) to fatigue on the last day of treatment. Serum free and total thyroxine and triiodothyronine were determined on the day of SET testing. Blood lactate and ECG data were collected during the SET at 6, 8, 10, 11, and 12 m/s and during recovery. The effect of treatment and SET on heart rate and blood lactate was examined using generalised linear mixed models. Post hoc analysis was adjusted for multiple comparisons using Tukey's Test. Data were expressed as mean ± standard deviation and P |
| Databáze: | OpenAIRE |
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