Indications

Flank abdominal approaches, whether for a hysterotomy or for gastrointestinal procedures, are the major reason this block is utilized.

Procedure

This block anesthetizes T13, L1, and L2 as they exit the intervertebral foramen. The pertinent anatomic landmarks are the head of the 13th rib and the transverse processes of the lumbar vertebrae.² The lumbar area is surgically prepped. Then the skin at the three injection sites is desensitized with 1 to 2 ml of 2% lidocaine. The first site (T13 block) is about 2 to 5 cm lateral to the midline, caudal to the head of the 13th rib, and cranial to the transverse process of L1. The second site (L1 block) and third site (L2 block) are also 2 to 5 cm off the midline and cranial to the transverse processes of L2 and L3, respectively. Next, a 14-gauge needle is inserted (at a 90-degree angle) into the site to facilitate passage of an 18-gauge needle for the actual deposition of the lidocaine. At each site an 18-gauge needle that is at least 10 cm in length is inserted through the 14-gauge needle to a depth of about 9 to 10 cm (“walking” off the transverse process to a depth 1 cm beyond the process) injecting 10 ml of lidocaine there and another 8 to 10 ml as the needle is removed.

The main disadvantage of this procedure is that it can be difficult in fat cattle.

Indications

Indications are the same as for the paravertebral block. However, this block can be performed more quickly and easily.

Procedure

This is simply a “line block” that follows the pattern of an upside-down L along the dorsal and cranial borders of the paralumbar fossa. Utilizing either a 20- or 18-gauge needle, 2% lidocaine is deposited every 3 to 5 cm along the aforementioned line. A total volume of 70 to 150 ml is typically utilized. The main disadvantages are the large volume of lidocaine required and inconsistent analgesia.

Indications

This block is most commonly used in preputial surgery in the bull, but it has applications for the cow as well. It can be helpful in chronic prolapse cases in which the bladder is also prolapsed. It is also indicated in any caudal urogenital procedure in which there is extreme tenesmus and an epidural does not seem adequate.³

Procedure

To perform this block, first prep the area of the ischiorectal fossa. Then by rectal palpation locate the lesser sciatic foramen. This is wrist deep and lateral. The lesser sciatic foramen is formed by the sacrosciatic ligament dorsally and the lesser sciatic notch ventrally. Following the intradermal injection of a small amount of lidocaine, a 14-gauge needle is placed through the skin in the ischiorectal fossa. Then a 6- to 8-inch 18-gauge needle is passed within the 14-gauge needle and with guidance from the hand within the rectum, the tip of the needle is placed in close approximation to the internal pudendal nerve. Then 20 to 75 ml of lidocaine is injected. Because these are paired nerves, swap hands and sides and repeat.

Indication

The sacral paravertebral nerve block provides longer “semipermanent” analgesia following caudal urogenital tract procedures in which other regional blocks do not adequately control tenesmus and avoids the potential negative side effects of the “alcohol” epidural.

Procedure

Because blocking the pudendal, middle hemorrhoidal, and caudal hemorrhoidal nerves is most easily facilitated by blocking S3, S4, and S5 as they branch off the spinal cord, the important anatomic landmarks are the foramina that are located lateral to the dorsal midline. Any lateral movement increases the difficulty, so squeeze chute restraint and tranquilization are recommended. A caudal epidural may be beneficial in the flighty or hypersensitive individual. Clip and perform a surgical prep of the skin over the dorsal sacrum. This completed, the S3, S4, and S5 foramina are located. This is best accomplished by first identifying the sacral-coccygeal joint (the most cranial of the joints movable when the tail is raised and lowered); 1 to 2 cm lateral to this are the paired S5 foramina. The S4 foramina are about 3 to 4 cm cranial, but more lateral and the S3 foramina are an additional 3 to 4 cm cranial. A stab incision dorsal to each foramen will facilitate the introduction of a 5- to 7-cm, 18-gauge needle. When the osseous ring is entered inject the 2 to 3 ml of the alcohol or alcohol/lidocaine mixture. An effective mixture is 1 ml of 2% lidocaine and 2 ml of 95% ethyl alcohol. This should effectively decrease tenesmus, while maintaining tail viability.

Indication

This block can be utilized when the cow is to be in ventral recumbency, maximum control of the hind limbs is desired, and facilities allow for a period of recumbency following the surgery.

Procedure

This procedure is the same as that for a routine caudal epidural except that the dosage of 2% lidocaine is 60 to 100 ml. The primary advantage, immobility of the rear legs, is also one of the prime disadvantages. Additionally, it is crucial that the head, shoulders, and thorax be elevated so that analgesia to respiratory centers does not occur.

Indications

This procedure is performed most commonly during the management of a dystocia, when the vulva has not fully dilated or there is a fetal-maternal size disproportion, and typically in heifers. Although an episiotomy helps to facilitate fetal passage during an assisted delivery, it is also performed to prevent tearing. Surgical closure is more effectively performed following an incision than with tearing, and undue trauma is avoided.

Surgical Technique

Typically the calf’s head is well into the vagina and is stretching the vulva when a decision is made to perform an episiotomy. Because the vulva is stretched so tightly even if epidural anesthesia has not already been employed, local anesthesia is rarely administered prior to the incision. Utilizing a scalpel, an 8- to 10-cm incision is made at the 10:00 or 2:00 position of the vulva, with the goal being to avoid the tearing of the vulva and perineum toward the rectum.

Following the delivery of the calf, the incision can be closed with a suture and pattern of your preference. Absorbable suture with a deep vertical mattress pattern is recommended. Absorbable suture eliminates the need for removal, although re-examination prior to breeding is recommended and the vertical mattress provides good apposition of both the submucosal and cutaneous layers. A surprisingly modest defect is created when the incision is left to heal by second intention, but because of the possibility that it may predispose the patient to pneumovagina, this is not recommended.

Aftercare

Complications, although rare, can usually be prevented by the administration of an antibiotic alone or with nonsteroidal anti-inflammatory drugs.

Indications

This procedure is performed primarily to correct pneumovagina. It is also performed sometimes following a colpotomy (see surgery of the uterus or surgery of the ovaries) to reduce the likelihood of postsurgical complications from an iatrogenic pneumovagina or eventration. Additionally it can be utilized with very mild cases of vaginal prolapse.

Anesthesia and Restraint

This procedure is performed with the cow standing, ideally restrained in a chute utilizing epidural anesthesia or a local infusion of lidocaine in the vulvar lips in the areas to be incised.

Surgical Technique

Utilizing scissors, a thin strip of tissue is removed from the dorsal one third to one half of the mucocutaneous junction of each vulvar lip. This can be facilitated by the injection of the lidocaine described previously. The lips of the vulva are then sutured together with a suture and pattern of the surgeon’s choice. Complications can result from overly aggressive closure, specifically causing a urine “backsplash” effect, but the procedure usually achieves its intended purpose.

Indications

Perineal lacerations in cattle most frequently result from excessive traction or an attempt to deliver a fetus through a nondilated birth canal. Unlike the mare, spontaneous perineal lacerations are uncommon in cows. First-degree lacerations involve only the mucosa of the vulva or vestibule and heal in many cases without treatment. Deeper lacerations may be complicated by prolapse of perivaginal fat and by bacterial infection of the genital organs or the urinary bladder. Treatment with systemic and local antibiotics is indicated in cases of infection.

Second-degree lacerations are deeper than first-degree lacerations and involve the entire wall of the vestibule and rectum and a portion of the perineal body but do not compromise the rectum or anus. The tissues are usually devitalized and contaminated by bacteria; thus, a period of 6 to 8 weeks should be allowed for healing before surgical closure of the defect. If second-degree lacerations are not corrected, incompetence of the vestibular sphincter allows aspiration of air and feces into the vaginal canal, which commonly leads to infertility.

Third-degree lacerations involve the vagina and the rectum as well as the perineal body and the anal sphincter and leave the patient with a common opening for the digestive and reproductive tracts. This is also termed as a rectovaginal tear. Considerable tissue damage and bacterial contamination accompany this injury, and most surgeons recommend that 6 to 8 weeks be allowed before attempting to correct the damage. Fecal contamination of the vagina, the cervix, and the uterus frequently, but not always, results in infertility until the defect is repaired.

Anesthesia and Restraint

Perineal lacerations can be repaired with the patient restrained in a stanchion or squeeze chute under epidural anesthesia in most cases. Light sedation may be needed in some cases to minimize movement by the patient.

Surgical Technique

Second-degree lacerations can be repaired by débriding the margins of the wound and bringing the dorsal portion of the vulvar labia into apposition with nonabsorbable suture material.

Several operative techniques have been described for surgical repair of third-degree perineal lacerations. The objective common to all procedures is to rebuild the shelf of tissue between the rectum and the vestibule and restore the integrity of the perineal body.

In contrast to mares, the feces of cows are soft, and most surgeons do not withhold feed and water prior to surgery. After the rectum is manually emptied of feces, the tail is tied away from the surgical field and the area prepared for aseptic surgery. A tampon made of a 4-inch stockinette filled with cotton can be placed deep in the rectum and tied to the tail with umbilical tape to assist in control of fecal soiling of the surgical site. Exposure of the surgical area can be achieved by placing retraction sutures on both sides of the anal sphincter and in both vulvar lips. Tension can be exerted on the sutures by assistants, or the sutures can be anchored to the skin.

A technique originally developed in mares has been modified and successfully used to repair third-degree perineal lacerations in cows. A horizontal incision is initiated along the junction between the rectal and vestibular mucosa from the dorsal commissure of the vulva to the shelf that lies between the intact rectum and the vestibule. The rectal and vestibular tissues are separated and the incision continued caudally at the same level to the dorsal vulvar commissure on the opposite side. Flaps of tissue, which will be used to separate the rectum and vestibule, are then formed by dissecting the vestibular mucosa on both sides ventrally for a distance of 3 cm. At the cranial limit of the laceration, the rectum and vestibule are separated for a distance of 4 to 6 cm.

Closure of the laceration is begun by the placement of two or three Lembert sutures of number 3 absorbable suture material transversely in the vestibular submucosa in the area of separation between the vestibule and rectum. Modified Lembert sutures are then placed at 1-cm intervals to appose and invert the vestibular flaps. The needle is first introduced into the perivestibular tissue, then into the vestibular submucosa in the dissected flap. The suture is then carried across the laceration and reintroduced into the vestibular submucosa of the opposite flap and finally continued into the perivestibular tissue on the opposite side and tied. The suture line is continued until the defect is closed to the level of the dorsal commissure of the vulva. The rectal mucosa is avoided in placement of the modified Lembert sutures. Concurrently, a continuous horizontal mattress suture is used to appose and seal the vestibular mucosa. Two or three modified Lembert sutures are placed, followed by two or three bites of the horizontal mattress suture until the shelf between the rectum and vestibule is re-established. The perineal body and dorsal portion of the vulvar labia are then débrided and apposed with interrupted sutures to restore their integrity and prevent aspiration of air and contaminants into the reproductive tract.

Aftercare

Procaine penicillin G (22,000 IU/kg, IM or SC, every 12 hours) is administered for 4 to 5 days after surgery. NSAIDs can be used for a short time after surgery to minimize dyschezia. A gentle digital examination of the vaginal side of the surgical site can be performed to assess healing after 2 weeks. Palpation per rectum should be avoided for at least 30 days. Uterine infections secondary to fecal contamination should be treated as indicated. Natural mating should not be permitted for at least 6 weeks after surgery or, because manipulation of the rectum is required, artificial insemination for at least 8 weeks.

The prognosis for successful repair and restoration of reproductive function is good, but rectovestibular fistulae may form in some cases. Less commonly, wound dehiscence results in partial or complete failure of the closure. Small rectovestibular fistulae may not result in infertility in all cases. Perineal lacerations do not commonly recur at the subsequent calving.

Indications

Urovagina or urine pooling is encountered less commonly in cows than in mares and is frequently a sequela to obstetric trauma. The cervix falls below the pelvic floor, which allows urine to flow forward and pool in the cranial vagina rather than flow caudally through the vulvar cleft. Infertility due to the spermicidal action of urine and chronic endometritis may follow. A procedure for creating an extension of the urethra in mares has been modified and adapted for use in cows.