The objective of this study was to identify the effects of combined anesthetic drugs on heart rate variability (HRV), respiratory function and recovery behavior in horses. Eight healthy Thai native crossbred horses were enrolled in this study. Horses were premedicated and induction with 2 protocols, protocol 1; acepromazine (0.04mg/ kg)+ xylazine (1 mg/kg)+ ketamine (2.2 mg/kg) and protocol 2; detomidine (5 mcg/kg)+ketamine (2.2 mg/kg). Heart rate and heart rate variability of 8horses were measured 20 minutes before and after administered the anesthetic drugs. Doppler was used to obtained systolic, diastolic and mean blood pressures. After anesthetic drug administration, horses premedicated and induction with acepromazine, xylazine and ketamine had the lower HR values when compared with another protocols. The HRV low frequency (LF) and high frequency (HF) powers ratio increased in horses premedicated and intubation with detomidine and xylazine. The marked hypoventilation were observed after anesthetic drugs administration in both groups. There were only minimal differences in the quality of recovery. However, overall of recovery scores were higher in group of protocol 1. This study demonstrated that acepromazine + xylazine + ketamine preserved the cardiovascular function and safe to use for the surgical applicability in horses.

Two horses diagnosed with underrun heels leading to navicular syndrome were fitted with Z-bar shoes. They occasionally showed moderate lameness on the affected legs after the sixth and tenth consecutive farrier adjustments. The affected hooves were sensitive to compression of the frog and sole in their palmar regions. Modified Z-bar shoes were created and shod on the lame legs based on previous with regional anaesthesia and recent clinical examination. The lameness scores were slightly improved at the first shoeing with the modified Z-bar shoes but were markedly improved at four and eight weeks aftershoeing, without medication. The modified Z-bar shoes in this report could potentially protect the palmar structure damaged by usual Z-bar shoes and contribute to reducing pathogenic impacts deriving from underrun heels and navicular syndrome.