Handout_Goat_C-Section_KMueller.pdf

Caesarean section in the goat Karin Mueller MVSc DCHP DECBHM MRCVS First published in the GVS Journal (2011, 27: 34 – 38). Reprinted with kind permission of the Goat Veterinary Society. In small ruminants, caesarean sections are generally less often performed compared to cattle. This is due to the...

Caesarean section in the goat Karin Mueller MVSc DCHP DECBHM MRCVS First published in the GVS Journal (2011, 27: 34 – 38). Reprinted with kind permission of the Goat Veterinary Society. In small ruminants, caesarean sections are generally less often performed compared to cattle. This is due to the typical causes of dystocia in the various species: feto-maternal disproportion accounts for about half of all bovine dystocia cases, and caesarean section is often the only viable route of delivering the foetus. In contrast, disproportion is the cause in only about one in five caprine dystocia cases, with maldispositions being much more common. The latter can often be corrected per-vaginam. In the doe, indications for caesarean section include, in approximate order of importance:  Obstruction of the birth canal (soft tissue obstructions such as failure to dilate, scar tissue, vaginal prolapse; boney obstruction such as pelvic size or pelvic damage)  Feto-maternal disproportion  Uterine torsion  Rupture and tears to the reproductive tract  Malpresentation  Rare: Abortion, foetal monsters A study on 110 caesarean sections in Iraqi goats states as indications incomplete cervical dilatation in 64% of cases, feto-maternal disproportion in 28%, vaginal prolapse in 5%, and herniation in 1% (Majeed et.al., 1992). Does with male kids required caesarean section more often than those with female kids (70 vs. 30%) in this study, and just over 60% of cases were primiparous. Caesarean section may be an elective procedure where disproportion is suspected, gestation is prolonged or the doe is suffering from disease. Induction should be carried out whenever possible prior to elective caesarean sections. The author prefers a combination of corticosteroids (aids foetal preparation, e.g. lung surfactant, and separation of foetal membranes) and prostaglandin F2 (ensures luteolysis). The ideal time for the elective surgery is at the start of cervical dilatation. Fetotomy may be an alternative to caesarean section, and the technique described by Winter (1999) in the ewe can be very successfully applied to the doe. Anaesthesia and preoperative medication A brief clinical assessment should be carried out to establish the fitness for surgery of the patient (and the need for any other supportive treatment, e.g. pregnancy toxaemia). In the goat, the author prefers to carry out surgery under general anaesthesia. Dystocia is the exception. Using local anaesthetic, and sedation where necessary, means quicker recovery of the dam, allowing her to nurse her offspring, and there is usually less effect on the neonate from the drugs used. Please see separate notes for suitable drugs and dose rates. Specific considerations should be given to the following points:      Xylazine has a direct, oxytocin-like myotonic action, making the uterus more friable. Detomidine or butorphanol are a better choice for sedation. The toxic dose of local anaesthetic is easily reached when performing either a line or Lblock. Dilution of the local anaesthetic (1:1 with sterile water for injection or saline) is usually necessary to achieve a high enough distribution volume without exceeding the safe dose. Both a paravertebral block and a lumbo-sacral epidural can be performed without reaching toxic levels of local anaesthetic. The latter is performed in the same way as CSF collection (Mueller, 2010), but instilling the drug into the epidural space rather than penetrating the dura mater into the subarachnoid space. A disadvantage of this otherwise useful technique is that the goat will remain recumbent or ataxic for some time post-op. Regurgitation is a risk, especially with a heavily pregnant uterus creating high intraabdominal pressure. Position the animal so that its nose is lower than its throat. Hypothermia is as much a risk as in other surgical procedures, especially with a large area of the animal clipped. Work in as warm an environment as possible, cover as much of the body as possible, use ‘hot hands’ or similar, and avoid soaking the animal’s coat with fluids. Preoperative medication that needs to be considered includes antibiosis (e.g. a potentiated penicillin), NSAID, tetanus cover if not vaccinated, and a uterine relaxant (clenbuterol). Postoperative medication includes analgesia, oxytocin to aid involution, and calcium if deficiency suspected (e.g. primary uterine inertia). Fly strike is rarely a concern given the typical kidding season in the UK. Surgical procedure Surgery is typically carried out in the recumbent patient. The author prefers a left flank approach with the doe in right lateral recumbency. The paramedian, ventral midline or right flank approaches are alternatives. Where the foetus is emphysematous, the ventral midline approach provides the best access. It allows exteriorisation of the uterine horn prior to incision, thereby reducing abdominal contamination. From the dorsal position, lean the patient 30-45 towards you to aid this. The left flank is clipped from the penultimate rib to the tuber coxae, and from the transverse processes to near the midline. In long-haired breeds, duct tape can be usefully employed around the edges of the clipped area to keep the fleece away from the surgical site. The site is surgically prepared. Equally, the surgeon scrubs hands and lower arms. Strong consideration should be given to wearing surgical gloves and a sterile top or gown to minimise any infectious challenge in the immune suppressed, peri-parturient patient. A vertical flank incision of about 20 cm length is made in the centre to slightly caudal left flank, starting approximately one hand-width below the transverse processes. The incision must be undertaken with care, as the patient is conscious and therefore liable to move occasionally, the tissue layers are relatively thin, and a distended viscus (rumen, uterus) may be present adjacent to the body wall. Remembering the direction of the muscle fibres in the various layers greatly helps to ascertain depth and level of incision:  Head to back foot for the external oblique muscle  Hip to front foot for the internal oblique  Vertical for the transverse abdominis muscle Haemostasis is achieved with artery forceps, all of which are removed prior to exploring the abdominal cavity. A hand is inserted into the abdomen and the pregnant uterine horn nearest the flank incision found and manoeuvred into the incision. Orientation within the abdomen is often helped by initially placing the hand into the pelvic inlet, feeling the foetus within the uterus in that location, and then following the foetus and uterus down onto the horn. Usually, it is possible to exteriorise the horn containing the foetal extremities. The uterine incision is started between the claws of the foetus and extended to the hock (if back leg) or carpus (if front leg). The incision should be made reasonably close to the uterine body, to aid development of any additional foetus from the other horn through the same incision. Occasionally, this is not possible and a second uterine incision has to be made. To minimise blood loss, care should be taken to incise along the greater curvature where blood vessels are minimal, and to avoid incising into placentomes. The foetus is removed and passed to an assistant (e.g. owner, who has been briefed prior to surgery) for further care. Both horns are thoroughly explored for further kids. The placenta is only removed if it comes away easily. Otherwise, any protruding parts are resected, with the bulk left in place. The uterus is sutured with a continuous inverting pattern (e.g. Lembert or Cushing) through the serosa and muscular layer, using absorbable material, ideally on a swaged-on needle to reduce tissue trauma. Catgut is a good choice with less tearing of tissue and less persistence that may lead to scaring, compared to synthetic suture materials. Synthetic materials, such as polyglactin 910, offer more consistent material strength and better knot and handling qualities, however. Great care must be taken to avoid including the foetal membranes. The knots should ideally be buried. After uterine closure, the uterus is lavaged with warm sterile fluids, paying particular attention to removing any blood clots around the ovaries. Prior to routine closure of the abdominal wall, the surgeon may wish to instil intra-abdominal antibiotics (soluble and non-irritant, e.g. crystalline penicillin). If the doe was tied out during surgery, abdominal wall closure is often aided by releasing the leg ties. Prognosis & Complications Kid survival is reported as 65% in one study (Majeed et.al., 1992), with a lower rate of 42% reported in a study on small ruminants (Brounts et.al., 2004). Stage-two labour of longer than six hours prior to intervention carried a poorer prognosis for kid survival in the second study. Neonates delivered by caesarean section, especially if elective, may show suppressed respiratory effort, as they have not undergone the hypoxia and foetal-fluid expressing forces occurring with vaginal delivery. An assistant should be ready to receive the kid and revive where necessary (clear airways, stimulate by rubbing or irritating, doxapram, resuscitator). Time for the neonate to place itself into sternal recumbency was found to be a good indicator of acidosis in calves, with a normal time of 4 minutes versus >15 minutes in acidotic calves (Schuijt & Taverne, 1994). Additionally, colostrum uptake and passive transfer need to be ensured. Doe survival rates of 93 - 96% have been achieved, exceeding an 82% survival rate after manual correction and traction (Majeed et.al., 1992; Majeed, 1994). Complications after caesarean section and possible prevention points are shown in Table 1. Table 1: Reported complications after caesarean sections and possible prevention points Complication Cause & Prevention Retained foetal membranes Oxytocin post-op Endometritis Clean vaginal examination prior to surgery and clean kidding environment. Routine systemic antibiosis for caesarean section cases. Wound breakdown or Sutures too loose or too tight. Dead space not reduced between seroma muscle layers. Also technique (i.e. difference between surgeons), use of adrenaline in local anaesthetic, and cleanliness of surgical procedure. Subcutaneous emphysema Flank incision too small for surgeon’s arm and foetus. Peritonitis Neat uterine suture providing good seal, no incorporation of foetal membranes. Typically present within 72-96 hours post-op. References Brounts, S.H., Hawkins, J.F., Baird, A.N., Glickman, L.T., (2004) Outcome and subsequent fertility of sheep and goats undergoing cesarean section because of dystocia: 110 cases. Journal American Veterinary Medical Association 224: 275-279 Majeed, A.F., Taha, M.B., Azawi, O.I. (1992) Caprine caesarean section. Small Ruminant Research 9: 93-97 Majeed, A.F. (1994) Obstetrical problems and their management in Iraqi goats. Small Ruminant Research 14: 73-78. Mueller, K. (2010). Clinical procedures in goats. Goat Veterinary Society Journal 26: 15-18 Schuijt, G., Taverne, M.A. (1994) The interval between birth and sternal recumbency as an objective measure of the vitality of newborn calves. Veterinary Record 135:111-115 Winter, A. (1999) Dealing with dystocia in the ewe. In Practice 21:2-9