Local anesthetic block techniques have existed in some form for decades and were initially heavily relied upon for analgesia and anesthesia in the early 20^th century. With the advent of better general anesthetic techniques, veterinarians lost the art of performing local anesthetic blocks. Many blocks are easy to perform and can play a vital role in the multi-modal approach to analgesia in veterinary patients.

Local Anesthetics

Lidocaine and bupivacaine are the most commonly used local anesthetics in small animal practice. Lidocaine has a very rapid onset but a relatively short duration, approximately 60 minutes. Toxic doses of lidocaine initially induce confusion, followed by more severe central nervous system effects, such as seizures. High doses can eventually produce death.

Bupivacaine has a relatively slow onset, approximately 20 minutes, but a relatively long duration, averaging 4 hours. The duration of action can be lengthened by using bupivacaine with epinephrine (1:200,000). The epinephrine vasoconstricts locally and decrease the uptake of bupivacaine, thus increasing its duration of effect. Like all local anesthetics, aspiration of the syringe to assure the needle is not in a vessel is very important. Bupivacaine is very cardiotoxic. Intravenous injection can result in non-resuscitatable cardiac arrest and DEATH. Always aspirate.

Specific Local Anesthetic Blocks:

Local anesthetic blocks that are easy to perform with minimal hands on training include interpleural blocks for thoracic and cranial abdominal pain, mandibular blocks for unilateral mandibular pain, infraorbital blocks for analgesia of dorsal nose, mental nerve blocks for analgesia of the rostral skin and gums of the mandible.

Epidurals with local anesthetics can provide excellent analgesia of the rear limbs and abdomen. These require significantly more training in order to perform them with confidence.