Segmental thoracolumbar spinal (subarachnoid) analgesia in conscious horses.

This research article presents a new technique for achieving segmental subarachnoid analgesia in horses, which numbs a specific section of the spine without affecting the animal’s ability to move. The method involves injecting a mepivacaine hydrochloride solution into the subarachnoid space along the spine, after which it takes between 5 and 10 minutes to take effect and lasts for roughly 42.4 minutes on average.

Method of the Study

• The research was conducted using 13 adult horses of both genders, each weighing around 500 +/- 60 kg. The researchers used a 17-gauge Huber point (Tuohy) needle to insert a catheter with a stylet into the subarachnoid space at the lumbosacral intervertebral space in the horses’ backs. They then moved it along the spine to the thoracolumbar area.
• The researchers determined the final placement of the catheter by radiographic examination.

Administration and Effect of the Analgesic

• Once the catheter was correctly placed, a solution of 2% mepivacaine hydrochloride (1.5 ml, 30 mg) was slowly injected into the catheter over a period of 60 seconds.
• The effect of the analgesia was observed to begin within 5 to 10 minutes of the injection and lasted for around 42.4 +/- 15 minutes, ranging from 25 to 68 minutes in total.
• The area of the horses’ spines affected by the analgesia stretched between the T12 and L3 segments on both sides of the spinal column.
• The researchers detected significant increases in the horses’ heart rate and skin temperature alongside decreases in their respiratory rate and rectal temperature after administering the mepivacaine hydrochloride.

Study Control and Implementation

• In a control group made up of 7 horses, the same protocol was implemented but with the injection of sterilized water (1.5 ml) into their spinal columns. In these control animals, the researchers noticed no significant changes like those observed in the main group.
• The researchers demonstrated the surgical application of the segmental subarachnoid analgesia technique in one horse.

Assessment of Outcomes

• The research paper also gave an overview of the benefits and potential complications of applying segmental subarachnoid analgesia in horses.
• This study paves the way for safer and more effective surgical procedures in equine medicine, particularly for surgeries that require analgesia in specific parts of the horse’s body.