A kinematic comparison of the locomotor pattern of horses sedated with detomidine alone and in combination with low doses of butorphanol.

BACKGROUND: Chemical restraint is often used to perform diagnostic and minor surgical procedures; α2 -adrenoceptor agonists are the most commonly used drugs; however, the combination with an opiate can induce a profound sedation. There is a lack of kinematic studies examining the effects of the combination of these drugs on locomotor patterns. OBJECTIVES: The objective of the study was to evaluate the duration of the effects of sedation with detomidine and detomidine combined with a low dose of butorphanol on the movement patterns of horses. STUDY DESIGN: The study was a controlled, randomised, blinded and crossover experiment. METHODS: Each of six horses was injected intravenously with saline (0.9%) solution (10 mL), detomidine diluted in saline solution (0.01 mg/kg bwt) or a combination of detomidine (0.01 mg/kg bwt) and butorphanol (0.02 mg/kg bwt) diluted in saline solution, in a random order. A single accelerometer positioned at the sacrum was used for gait assessment 15 min before (baseline) and 5, 15, 30, 45, 60, 75, 90, 105 and 120 min after each injection. Eight variables were measured, including speed, stride frequency, stride length, regularity, dorsoventral power, propulsive power, mediolateral power and total power; force of acceleration and the three components of power were calculated. The degree of sedation was measured by the ground-to-lip distance. RESULTS: There were significant differences among groups, with shorter effects after the injection of the combination of drugs, for most parameters. MAIN LIMITATIONS: A small number of horses were involved in the study. CONCLUSIONS: The combination of detomidine and butorphanol produces a shorter effect on almost all accelerometric parameters, probably due to the excitement produced by the opioid drug causing a quicker return to normal values. Accelerometry offers a method of objectively monitoring gait abnormalities in walking sedated horses.

Pharmacokinetics and local tolerance of cefovecin sodium after intra-articular administration in horses.

Searching for new therapeutic options against septic arthritis in horses, this research was focused on the study of the kinetics and local side effects after the intra-articular treatment of horses with cefovecin sodium. A single dose (240 mg) of the drug (Convenia® ) was administered into the radiocarpal joint of adult healthy horses (n = 6), and drug concentrations in plasma and synovial fluid were determined by high-performance liquid chromatography (HPLC). Local tolerance was also studied based on the modification of different joint physiopathological parameters (pH, cellular, and protein concentration in synovial fluid). Although no clinically relevant joint damage was noticed, significant increases in the protein concentrations at 5 min and in the cellular concentration at 30 min after cefovecin administration were observed in the treated radiocarpal joints. The duration of the cefovecin above the minimal inhibitory concentration (MIC) ≤1 µg/mL was 28.80 ± 2.58 h in the radiocarpal joint and 16.00 ± 2.86 h in plasma. The results of this study showed that intra-articular administration of cefovecin sodium in horses could be considered in the future to manage septic arthritis in horses, as it offers a good pharmacokinetic behavior and good local tolerance.

Effect of alkalinization on the local analgesic efficacy of ketamine in the abaxial sesamoid nerve block in horses.

The objective of this study was to determine the effects of the alkalinization on the local analgesic efficacy of 1% ketamine in the abaxial sesamoid nerve block in horses. Thirty-six mature healthy horses were randomly assigned to four groups for the following treatments; an abaxial sesamoid block with 5 mL of saline solution (control saline); an abaxial sesamoid block with 5 mL of a solution containing 1% ketamine (KETs 1%); an abaxial sesamoid block with 5 mL of a solution containing saline solution and 0.5 mEq of sodium bicarbonate (control bicarbonate); and an abaxial sesamoid block with 5 mL of a solution containing 1% ketamine and 0.5 mEq of sodium bicarbonate (KETb 1%). All blocks were performed in one randomly selected front leg. To determine analgesia, hoof withdrawal from thermal stimulus from radiant heat lamp was assessed. Before each block, the hoof withdrawal reflex latency (HWRL) (time between lamp illumination and withdrawal of the hoof) was determined; after the block, local analgesic effects were determined using the heat lamp at 2 and 5 min after the injection and then every 5 min for 1 h. In KETs 1% group, there were significant increases in HWRL between basal values and values from 2 to 10 min after an abaxial sesamoid block. In KETb 1% group, significant increases in HWRL was collected between the basal value and values from 2 to 25 min following an abaxial sesamoid block. In KETs 1% group, of the nine horses, four had an abaxial sesamoid block that was unsuccessful. However, in KETb 1% group, only one of the nine horses had an abaxial sesamoid nerve block that was unsuccessful. The alkalinization of a 1% ketamine solution produced a more consistent and persistent local analgesia in horses when compared with 1% ketamine solution alone.

Effects of alpha-2 adrenoceptor agonists during recovery from isoflurane anaesthesia in horses.

REASONS FOR PERFORMING STUDY: Recovery from inhalant anaesthesia in the horse is a critical and difficult period to manage; however, several factors could help to obtain a calm recovery period including choice of anaesthetic and analgesic procedure used and the conditions under which anaesthetic maintenance and recovery occur. OBJECTIVES: The objective of this study was to evaluate and compare the quality of recovery in horses administered saline, xylazine, detomidine or romifidine during recovery from isoflurane anaesthesia. METHODS: Six mature and healthy horses were premedicated with i.v. xylazine and butorphanol, and anaesthesia induced using ketamine. After 2 h of inhalant anaesthesia with isoflurane vaporised in oxygen, saline solution, xylazine (0.1 mg/kg bwt), detomidine (2 microg/kg bwt) or romifidine (8 pg/kg bwt) were administered. The quality of recovery of each horse and the degree of sedation and ataxia were evaluated. Cardiovascular and respiratory parameters were recorded, and arterial blood samples obtained and analysed for pH, PO2 and PCO2 during recovery. RESULTS: Quality of recovery was better in groups treated with alpha-2 adrenergic receptors agonists, showing less ataxia. Degree of sedation was greater in the romifidine group. CONCLUSIONS: We concluded that the administration of alpha-2 adrenoceptor agonists during recovery from isoflurane anaesthesia in horses prolonged and improved the quality of recovery without producing significant cardiorespiratory effects. POTENTIAL CLINICAL RELEVANCE: Administration of alpha-2 adrenoceptor agonists after inhalent anaesthesia could prevent complications during the recovery period.

Anesthetic potency of desflurane in the horse: determination of the minimum alveolar concentration.

OBJECTIVE: To determine the minimum alveolar concentration (MAC) of desflurane (DES) in the horse. STUDY DESIGN: Prospective study. ANIMALS: Six healthy adult horses (three males and three females) weighing 370 +/- 16 kg and aged 9 +/- 2 years old. METHODS: Anesthesia was induced with DES vaporized in oxygen via a face mask connected to a large-animal, semiclosed anesthetic circle system. The horses were endotracheally intubated and positioned in right lateral recumbency. Inspired and end-tidal DES were monitored using a calibrated Ohmeda RGM 5250 multigas analyzer (Ohmeda-BOC, Spain). The MAC of desflurane that prevented gross purposeful movement in response to 60 seconds of noxious electrical stimulation of oral mucous membranes was determined. RESULTS: The time from the start of DES administration to lateral recumbency was 6.1 +/- 0.9 min. The MAC of DES in these horses was 7.6 +/- 0.4%. Time required for the animal to regain sternal recumbency after 98 +/- 4 minutes of anesthesia was 6.6 +/- 0.5 minutes and the time to standing was 14.3 +/- 2.7 minutes. CONCLUSIONS: The MAC of desflurane in these horses was 7.6 +/- 0.4%. DES provided a rapid induction to, and recovery from, anesthesia. CLINICAL RELEVANCE: Desflurane offers the potential for more precise control during anesthesia, and may allow a faster and uneventful recovery. It is important to know the MAC of an inhalant to use it clinically.