Documents

BovineCesareanintheField.pdf

Description
Description:
Categories
Published
of 22
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
  This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institutionand sharing with colleagues.Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third partywebsites are prohibited.In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further informationregarding Elsevier’s archiving and manuscript policies areencouraged to visit:http://www.elsevier.com/copyright  Author's personal copy Bovine Cesarean Section in the Field Kenneth D. Newman, DVM, MS Prescott Animal Hospital, 2725 Edward Street North, Prescott, Ontario, K0E 1T0, Canada The ideal goals in performing a cesarean section are preservation of thecow and calf and the future reproductive efficiency of the cow. Both breed(eg, dairy versus beef) and experience tend to influence the frequency,ease, and success of this procedure. Dairy practices tend to perform fewercesarean sections, but these occur year round. In comparison, cesarean sec-tions in beef practice are numerous and heavily concentrated during the latewinter and early spring. Furthermore, adverse weather conditions associatedwith beef calving practices require appropriate farm facilities for performingcesarean sections. The ambient environmental temperature in some regionsacross North America may not always be conducive to on-farm surgery, es-pecially in some beef operations. A number of variables determine whetherthe procedure is successful. The health status of the cow and calf at the timeof surgery is recognized as the most important determinant of outcome[1–3]. For this reason, it is worthwhile to categorize a cesarean section asan elective, emergency (nonemphysematous), or emphysematous procedure.This article covers the indications, approaches, anesthesia, and surgicaltechniques for cesarean section in the field. Indications The indications for performing a cesarean section include maternal andfetal factors [1,2,4]. Maternal indicators include: immature heifers, pelvic de-formities, failure of cervical dilation, uncorrectable uterine torsion, uterinetear, hydrops, and prepartum paralysis [4]. Risk factors in cattle are in-creased by the heifers’ age if less than 2 years old (odds ratio 3.09 comparedwith multiparus cows), a long gestation period, a preceding long intervalfrom first service to conception, a long dry period, a double-muscled [5,6](odds ratio 10.85 compared with non-double-muscled breeds) [7] or Pied-mont sire (odds ratio 4.26 compared with other breed sires), and previous E-mail address:  hoofandpaw.locumvetservices@yahoo.ca0749-0720/08/$ - see front matter    2008 Elsevier Inc. All rights reserved.doi:10.1016/j.cvfa.2008.02.009  vetfood.theclinics.com Vet Clin Food Anim 24 (2008) 273–293  Author's personal copy cesarean section calving (odds ratio 18.89 compared with those having a pre-vious normal calving) [7].Fetal indicators include normal and pathologic fetal conditions [2,4].Normal fetal conditions consist of absolute fetal oversize (relative toa normal maternal pelvis size) and malposition. A high value calf, such asan embryo transfer or clone, may be an indication for an elective cesareansection. Pathologic fetal conditions include fetal anasarca, schistosomus re-flexus, hydrocephalus, conjoined twins, emphysematous, mummification,and prolonged gestation. Depending on the circumstances, including theavailability of a fetotome and the practitioner’s experience, a fetotomy isnot always a viable option. It is inadvisable to attempt a fetotomy if the cer-vix is dilated incompletely, or when the uterus is either tightly contracted orfriable [4]. Case selection Case selection tends to be overlooked by clients and veterinarians. Whena cesarean section is considered an option of last resort, a negative outcomeis more likely; therefore, a cesarean section tends to be a self-fulfillingprophecy [1,3,8,9]. When a cesarean section is chosen early in dystocia cases,the procedure is more rewarding and clients are more agreeable to futurecesarean sections. Categorizing the procedure as an elective, emergency(nonemphysematous), or emphysematous procedure is worthwhile, becausethe expected outcomes and anticipated complications are dramaticallydifferent for these three situations.The condition of the cow at the time of surgery is recognized as a majordeterminant affecting outcome [1–3,8,10]. Cows undergoing elective cesar-ean section surgery are less likely to encounter intraoperative and postoper-ative complications. Cows that have an emergency cesarean section (eg,malpresentation or uterine torsion) are more likely to encounter intraoper-ative and postoperative complications (eg, peritonitis) and are less likely tosurvive. Rapid clinical assessment (eg, less than 20 minutes) was associatedwith improved successful outcomes in two practitioner surveys [9,11] and inthe author’s experience. The ideal emergency case is a cow that has been inlabor briefly, that has a live calf, and the decision to perform a cesarean sec-tion is made quickly without prolonged obstetric manipulation by either theclient or the attending veterinarian. Excessive manipulations by the ownerand veterinarian without making progress toward successfully deliveringthe calf alike were associated with higher postoperative complications. If the front legs and head cannot be manipulated into the birth canal, the de-cision to perform a cesarean section should be immediate. Furthermore, toaccommodate larger hips associated in beef breeds, there should be sufficientroom in the pelvic canal for the calf’s head and front legs, with space re-maining to sweep an arm around the calf’s shoulders to safely extract thefetus through the birth canal. 274  NEWMAN  Author's personal copy Approach The traditional approaches have been described well in previous litera-ture [1–4,12,13]. Appropriate restraint (based on the breed), space, light,available help, location, and the veterinarian’s experience and confidence[4] are issues that need to be considered in conjunction with the underlyingreason for performing the cesarean, since these can determine the surgicalapproach [1,4,12]. The two main options are whether to perform surgeryon a standing or recumbent cow. Depending on the demeanor of the cow,a recumbent approach using sedation and tying the legs forward and backmay be more appropriate in cases when no chute is present. If the cowmay not remain standing for the duration of the surgery, it may be easierto start with her in a recumbent position rather than having her fall downintraoperatively. The recumbent approach facilitates exteriorization of theuterus, especially when an oversized fetus is present (eg, emphysematous),thus reducing the opportunity of abdominal cavity contamination [12]The recumbent approach can be either midline or directly over the pregnanthorn (eg, paramedian or low-flank) [12].The standing flank approach may be done from either the left or right,but it is more commonly performed from the left [1,4,11,12]. The primaryadvantage of the left approach is that the rumen prevents evisceration of the small intestines. Rumen prolapse may occur if the cow strains duringsurgery, which may prevent manipulation and exteriorization of the uterus.A caudal epidural anesthesia may reduce abdominal straining. Rumen pro-lapse also may be reduced by using a stomach tube as a naso-tracheal tubeto inhibit buildup of positive abdominal pressures. In the most extremecases (eg, downer cow), the author has performed a rumenotomy to removesufficient rumen contents to facilitate completion of the cesarean sectionwithout adversely affecting cow and calf outcome. When the pregnancy islocated in the right horn, some practitioners find it easier to use the rightapproach to exteriorize the gravid horn, but retaining the small intestineswithin the abdominal cavity potentially may be more difficult.A left oblique approach in standing cows has been described by Parishand colleagues [14]. This technique may be useful when removing largecalves or when the uterine contents are contaminated. This incision is largerand extends more cranial-ventrally compared with the traditional verticalincision. An incision is started 10 cm cranial and 8–10 cm ventral to thecranial aspect of the tuber coxae. The incision is extended cranioventral ata 45 degree angle, ending 3 cm caudal to the last rib. The apex of the uterinehorn is more readily accessible, therefore facilitating manipulation and exte-riorization of the uterus. The internal abdominal oblique is incised parallelto the muscle fibers; the abdominal viscera apply tension to this muscle,which causes apposition during closure.Some producers have heated facilities when calving assistance or cesareansections are required. In an extreme situation (eg, unheated barn and 275 BOVINE CESAREAN SECTION IN THE FIELD
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks
SAVE OUR EARTH

We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

More details...

Sign Now!

We are very appreciated for your Prompt Action!

x