Epidural co-administration of neostigmine and lidocaine or xylazine enhances systemic sedation but not perineal analgesia in adult dairy cows

The aim of this study was to evaluate the behavioural, clinical and analgesic effects of epidural neostigmine in adult dairy cattle. Five healthy, adult Holstein-Friesian dairy cows received five different treatments in a cross-over design with one-week washout period as follows: 2% lidocaine alone (0.22 mg/kg), neostigmine alone (10 μg/kg), neostigmine-lidocaine (10 μg/kg and 0.11 mg/kg), neostigmine-xylazine (10 μg/kg and 0.05 mg/kg) and 0.09% saline alone (6 ml). Analgesia of the perineal region was assessed using the superficial and deep muscle pin-prick techniques. The onset and duration of analgesia and the degree of analgesia, sedation and ataxia were assessed before drug administration (T0) and thereafter at T15, T30, T60, T120 and T180. In addition, cows were monitored for any behavioural or clinical abnormalities over the course of the entire study. Signs of agitation, increased salivation and increased frequency of defecation were observed in cows administered neostigmine epidurally alone or in combination with lidocaine or xylazine. The epidural administration of neostigmine alone did not result in any analgesic effects in any of the cows. Analgesia appeared significantly faster (P ≤ 0.05) in the lidocaine group compared to the neostigmine-lidocaine and neostigmine-xylazine groups. The duration of analgesia produced by neostigmine-xylazine was significantly longer (P ≤ 0.05) than that produced by lidocaine alone or neostigmine-lidocaine. Neostigmine produced a significant degree of sedation (P ≤ 0.05) when administered epidurally alone or in combination with lidocaine or xylazine. The epidural administration of neostigmine alone did not result in any signs of ataxia, while the epidural administration of lidocaine alone, neostigmine-lidocaine and neostigmine-xylazine resulted in variable degrees of ataxia. There were no significant changes in any of the clinical parameters. In conclusion, neostigmine can be co-administered epidurally with lidocaine or xylazine for routine standing surgical procedures in adult dairy cows to enhance sedation but not analgesia.