Vaquejada is a high-intensity and short-duration exercise in which helper horses (HH) are responsible to keep a bull running in a line while pull horses (PH) work to put the bull down after 100 m of running. The purpose of this study was to quantify and compare energy expenditures (EE), transport costs (COT) and metabolic energy requirements (Pmet) of horses used in Vaquejada. Thus, eight Quarter Horses, in randomly formed pairs, performed a vaquejada simulation test (VST), which consisted of three races on a sand track (130–150 m), with a 5-min interval between them. All horses used an integrated heart rate (HR) and GPS monitoring system (V800, Polar Electro) and, from these data, EE, COT and Pmet were calculated using the formulas: EE (J/kg/min) = 0.0566 × HR^1.9955, COT = (HR-35)/kg/m × 10³ and Pmet = (HR-35)/min/kg. Blood samples were collected for lactate analysis at rest, immediately after the first, second and third race and after 30 min of recovery. Data obtained were submitted to one-way ANOVA and Tukey tests (p ≤ 0.05). In VST, HH had higher EE and higher HR at trot; while PH presented higher EE and HR at canter. Finally, considering total VST, PH had higher EE and COT, while HH had higher Pmet. Lactate was higher in PH. Despite practicing the same sport, PH and HH should be considered distinct athletes, and these must be considered to set up appropriate physical and nutritional programs, which will lead to better performance and guarantees of well-being.

Morphine has significant clinical and analgesic effects in horses, but its impact on the gastrointestinal tract requires further understanding. This study assessed the analgesic and gastrointestinal effects of morphine in horses undergoing elective orchiectomy in the quadrupedal position. Thirty uncastrated male horses were randomly assigned to three groups: orchiectomy without morphine and sedation protocol (OSM), orchiectomy with morphine and sedation protocol (OM), and administration of morphine alone in the absence of orchiectomy (M). The anesthetic protocol involved acepromazine (0.05 mg/kg IV) and detomidine (10 mcg/kg IV) sedation in groups OSM and OM, with morphine sulfate (0.05 mg/kg IV) given to OM and M, and NaCl to OSM. The team measured clinical parameters, pain, and sedation using the EQUUS-FAP scale, while they monitored bowel motility and gastric dilation through abdominal ultrasound. These assessments were performed on the previous day (m1), 20 min before surgery (m2), and at various time points following the administration of morphine or saline solution: one hour (m3), two hours (m4), four hours (m5), six hours (m6), and eight hours (m7) post-procedure for all three groups. There was no significant difference in pain score between OSM and OM, though OM had better sedation. Ultrasound revealed decreased colon contractions and minor gastric dilation in OSM and OM, normalizing within 6 h. Group M showed reduced motility and significant gastric dilation lasting 8 h. In conclusion, while morphine enhanced sedation without causing greater gastrointestinal dysfunction than OSM, its administration alone resulted in a more pronounced reduction in gastrointestinal motility and an increased risk of gastric dilation.

The present study involved seven horses in a randomized crossover clinical trial to evaluate the effect of lidocaine on horses with induced endotoxemia. Horses received intravenous lidocaine (1.5 mg/kg bolus, followed by 0.05 mg/kg bwt/min) or placebo (0.9% sodium chloride at the same manner) one hour before LPS administration (0.03 μg/kg, IV infusion over 30 min). We monitored clinic and hematologic parameters, abdominal auscultation, ultrasound, and pain over time. No relevant clinical differences existed between treatments regarding peristalsis, abdominal pain, or any other parameters before and after endotoxemia induction. These findings do not support the clinical use of lidocaine to mitigate abdominal pain and intestinal hypomotility promoted by endotoxemia in horses.

The purpose of this study was to assess the stress responses associated with vaquejada simulating tests (VSTs). Ten clinically healthy 8.9 ± 4.3-year-old Quarter horses, weighing 441.3 ± 25.0 kg, performed two VSTs five days apart. In the first VST (M1), animals ran three times with a 5-min rest between races; and in the second (M2), they ran with a 15-min rest between races. Horses were examined before (T0) and immediately after the third run (T1) and at 4 h (T2) of recovery. Stress biomarkers included heart rate (HR), heart rate variability (HRV), cortisol, and white blood cell count. All variables were analyzed by ANOVA and Tukey tests, considering p < 0.05. A significant reduction in cortisol was observed for pull (p = 0.0463) and helper (p = 0.0349) horses when they had a 15-min rest between races. The rMSSD and mean R-R values for helper horses were also significantly lower in M2. In conclusion, the 15-min rest interval proved to be better than the 5-min period for both categories of equine athletes used in vaquejada mainly for helper horses. A longer rest time between races allowed the organic recovery necessary for these animals to impose a greater applied physical effort load, which is a fact that guarantees good performance and well-being.