Surgical Correction of Abnormalities of Genital Organs of Cows

CHAPTER 60 Surgical Correction of Abnormalities of Genital Organs of Cows



Many urogenital problems in the cow mandate culling because of economic considerations and unfavorable prognosis; however in some situations the value of the animal dictates an attempt at treatment, with restoration of fertility the goal. Because most urogenital accidents or injuries occur in conjunction with pregnancy or parturition, the goal of surgical intervention may be simply to allow for delivery of the calf, or if parturition has occurred, allow for increased weight gain of the calf or cow for sale at a later date. Thus, although restoration of fertility may not always be achieved, a salvage procedure is often an economically viable option.



ANESTHETIC CONSIDERATIONS


Most procedures described here can be performed while the animal is standing, with good restraint and well-utilized local anesthesia; minimal sedation is required. Although it is understood that tranquilization does not provide analgesia, it is important to remember that with cattle, controlling anxiety is just as important. Alternatively, it is also important to consider the side effects of most sedatives. Xylazine, for example, increases uterine contractions and decreases uterine profusion and oxygenation.1 Also, most cows have a tendency to lie down when sedated. Therefore, light sedation with properly administered regional anesthesia is preferred for standing procedures. Additionally, it is typically beneficial to administer nonsteroidal anti-inflammatory drugs (NSAIDs) to minimize postsurgical inflammation and discomfort.


The regional anesthetic blocks most commonly employed are the epidural for most procedures involving the vulva, vagina, or perineum and either the inverted-L or paravertebral block for the flank approach celiotomy. Additional regional anesthetic techniques that may be of value are discussed as well.



Proximal Paravertebral Block




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.





Sacral Paravertebral Nerve Block






SURGERY OF THE VULVA AND PERINEUM



Episiotomy







Repair of Perineal Lacerations and Rectovaginal Tears



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.




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.



Sep 3, 2016 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on Surgical Correction of Abnormalities of Genital Organs of Cows

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