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E Q U I N E D E N T I S T RY — A N I N T R O D U C T I O N
displaced dorsally or ventrally. This block is similar to the infraorbital block in that the nerve is likely to be
contacted and the horse needs to be well restrained, sedated and have opiod analgesia. A 22-gauge, 1- or 1.5-
in. needle, is inserted towards the foramen from a rostral to caudal direction and 5 mL of local anaesthetic is
deposited at the foramen location.
Mandibular nerve block
The mandibular foramen is located by palpating or visualising a line thru where the upper and lower cheek
teeth meet running rostro caudal. A second line is then visualised from the lowest point of the ramus of the
mandible to the lateral canthus of the eye. Where these two lines intersect will approximate the location of the
mandibular foramen on the medial side of the mandible.
If a skull is available this will assist the practitioner in orientating these landmarks/locations. Good sedation
and restraint/support should be used when performing nerve blocks. Each practitioner will have their preferred
combinations and dose rates to suit the patient and situation; however as a starting point 0.8mg/kg xylazine in
combination with butorphanol used on patients restrained in stocks will provide good sedation and analgesia.
Local anaesthetic can be used at the site of entry of the needle. The author uses an 14 gauge 5¼ inch stillete
from a catheter inserted at the lowest point of the jaw in line with the landmarks described above. Before
inserting the needle it is advisable to measure on the lateral side approximately how far the needle will need to
be inserted. The needle is then inserted on the medial aspect of the jaw line. Examining a skull will demonstrate
that this part of the jaw is curved so that the lower third of the mandible rolls medially. Initially the needle
should be directed to follow this curve with the bevel orientated to face the medial aspect of the mandible the
practitioner should feel the needle skip over the bone and should adjust the angle to be more vertical after
approximately 2-3 cms. If the nerve is located by the tip of the needle the animal will usually give visible signs
(such as a flick of the head) that the needle is in the correct location. At this point 20 to 40 ml of local anaesthetic
can be slowly diffused in to the site. As with all blocks at least 10-15minutes should be given to allow the block
to take effect before commencing any invasive procedures. It is also a good idea to test the effectiveness of the
block at the end of this interval; this can be done by inserting a needle into the area.
Local perfusion
Any site that is not readily desensitized by a regional nerve block can be directly infused with local anaesthetic
solution to affect analgesia. Typical uses include skin desensitization for procedures involving the sinuses,
laceration repairs, mass removals, or biopsies. Manipulations within the paranasal sinuses are better tolerated
after instilling 50 to 60 mL of local anaesthetic into the sinus. Standing procedures of the ear can be pe