ternative to a caudal epidural for perineal lacera- tion and rectovaginal fistula repair consists of a local infiltration of the nerves lateral to the rec- tum. After appropriate skin preparation, a long needle is inserted lateral to the rectum along ei- ther side to a point cranial to the surgical area. A hand inserted in the rectum can assist needle placement. Local anesthetic is infiltrated as the needle is withdrawn. Local anesthetic (20–40 mL) is used on each side (Fig. 3). Epidural administration of opioids works well to provide analgesia to the hind limbs and perineal region. Epidural morphine is used most commonly and typically provides 12 to 18 hours of analgesia; the most commonly used dose is 0.1 to 0.2 mg/kg. The addition of 15 to 30 g/kg detomidine may in- crease the effectiveness and duration of analgesia provided by the morphine. If repeated doses are to be administered, an epidural catheter can be placed, as shown in Fig. 4. The introducer needle is placed
Fig. 3. Injection site for alternative block.
in a manner similar to a conventional caudal epidu- ral, and when the tip of the Touhy needle is in the epidural space, the catheter is advanced cranially approximately 10 cm. The catheter is then secured to the patient. The author prefers the noncoil-re- inforced catheters because they can be shortened to ease maintenance. In localized areas, placement of a perineural cath-
eter for continuous or frequent intermittent admin- istration of a local anesthetic can be an excellent method of providing analgesia. There are some dif- ficulties maintaining these catheters long term.
Fig. 2. Equine caudal epidural needle placement.
Fig. 4. Placement of an epidural catheter. AAEP PROCEEDINGS Vol. 61 2015 207
