Five regional anesthetic blocks can be used depending on the area of the oral cavity to be anesthetized. Except for the caudal
mandibular block, the blocks are easy to learn. It is helpful to have a skull to refer to when performing a block to help
visualize the anatomic landmarks. Make sure to insert the needle with the bevel facing out, and try to avoid repeatedly inserting
the needle. Because of the lag with the onset of anesthesia, perform these blocks 10 to 15 minutes before beginning the procedure.
The time between regional anesthetic injection and surgery can be used for scaling, oral and dental charting, taking intraoral
radiographs, or performing other painless procedures. ä
Figure 2. As seen with this cat's skull, the position of the needle with the caudal infraorbital nerve block could cause orbital
injury in a cat. For this reason, this block is not recommended in cats.
Cranial infraorbital nerve block
A cranial infraorbital nerve block anesthetizes only the ipsilateral incisors and canines of the maxilla. For this technique,
0.2 to 0.4 ml bupivacaine (0.5%) is injected into the opening of the infraorbital foramen, which is apical to the distal root
of the maxillary third premolar. Palpate the foramen through the oral mucosa, hold the syringe almost parallel to the maxilla
with the needle directed caudally, insert the needle 1 mm into the foramen, aspirate to ensure the needle is not in a blood
vessel, and inject the bupivacaine rapidly (Figure 1). In cats, do not attempt to advance the needle into the foramen because the feline infraorbital canal is short, and needles
placed into the foramen can cause orbital trauma.
Caudal infraorbital nerve block
A caudal infraorbital nerve block anesthetizes all ipsilateral teeth of the maxilla. This block is not recommended in cats
because of the short canal and the potential for orbital injury (Figure 2). Insert the needle 2 to 3 mm into the infraorbital foramen, and place a finger over the entrance to the foramen. Inject
0.4 to 0.8 ml (usually 0.4 for small dogs, 0.6 ml for medium-sized dogs, and 0.8 ml for large dogs) bupivacaine (0.5%) into
the foramen, causing the bupivacaine to flood the infraorbital canal and exit through the caudal opening of the canal (Figure 3).
Figure 3. The proper needle placement for the caudal infraorbital nerve block, which will block the entire unilateral maxillary
arch on the side injected.
Middle mental nerve block
A middle mental nerve block anesthetizes all ipsilateral incisors and canines of the mandible. Inject 0.2 to 0.4 ml bupivacaine
(0.5%) at the middle mental foramen, which is apical to the mesial root of the mandibular second premolar (Figure 4).
Figure 4. The proper needle placement for anesthetic injection at the middle mental foramen, which is apical to the mesial
root of the mandibular second premolar.
Caudal mandibular nerve block
A caudal mandibular nerve block anesthetizes all ipsilateral teeth of the mandible. This procedure is challenging to perform
accurately, so laboratory instruction is recommended before performing this block on patients.
Inject 0.8 to 1 ml bupivacaine (0.5%) at or near the mandibular foramen, which is on the lingual (inside) aspect of the mandible
above the mandibular notch. The mandibular notch can be palpated caudal to the last molar on the ventral surface of the mandible.
Insert the anesthetic needle through the skin, walk it off the ventral mandible, and advance it dorsally to the region of
the mandibular foramen (Figure 5).
Figure 5. The proper needle placement for the caudal mandibular nerve block.