Recent advances in equine abdominal surgery

Laparoscopy is a minimally invasive procedure that has applications as a diagnostic, therapeutic and prognostic technique. Specialized equipment is necessary to perform equine laparoscopy, and there is a large range of instruments, both disposable and non-disposable available. Laparoscopic procedures described include ovariectomy, cryptorchidectomy, adhesiolysis and herniorrhaphy. Laparoscopy can be performed in a standing or dorsally recumbent position, depending on surgeon preference, patient status and the procedure to be performed. Stapling equipment is frequently used in gastrointestinal surgery in horses. Advantages include decreased surgical time and a decrease in the risk of contamination. Stapling equipment is often used in creating anastomoses, both in the large and small intestines, as well as in vessel ligation. New surgical techniques intended to decrease adhesion formation include the use of carboxymethylcellulose and bioresorbable patches. Indwelling abdominal drains can be used for peritoneal lavage following surgery and also appear to decrease the risk of adhesion formation. Improvements in post-operative care, including the treatment of post-operative ileus and endotoxaemia can significantly improve the outcome of horses that have undergone surgery for abdominal disorders. Recommendations for the use of prokinetic agents in horses with ileus vary widely. Prokinetic agents include local anaesthetics, macrolide antimicrobials, cholinergic agonists and dopamine antagonists. Endotoxaemia is common in horses following surgery for gastrointestinal disorders. The antibiotic polymyxin B binds to the circulating endotoxin molecule, decreasing its half-life in the intra-vascular space and reducing associated inflammation. This drug appears to be an effective and affordable treatment option for horses with endotoxaemia. The use of specific cyclooxygenase inhibitors in veterinary medicine have been studied recently. Selective cyclooxygenase-2 inhibitors may provide comparable anti-inflammatory and analgesic properties to the non-selective non-steroidal anti-inflammatory drugs. These drugs appear to have similar clinical effectiveness and will hopefully minimize deleterious side effects. The optimal healing of ventral midline incisions in horses is related to many factors including appropriate suture patterns and bite size, in addition to appropriate post-operative exercise recommendations. Recent advances in surgical techniques and post-operative care should decrease the morbidity and mortality associated with abdominal surgery. This article provides an overview of some of these advances.     

Intensive care of the patient after abdominal surgery

After surgical correction of the underlying abdominal disorder, careful postoperative care is the most important factor resulting in increased survival rates. Intensive care of the postoperative patient can be done practically and economically.     

Suprapubic paramedian laparotomy for equine abdominal cryptorchidism.

The history of techniques for abdominal equine cryptorchidectomy is briefly reviewed. The technique of suprapubic paramedian laparotomy as used since 1955 at the University of Liverpool veterinary field station is described in detail and an account given of the authors' experience with the technique in nearly 200 cases. It is concluded that the approach to the abdominal cavity is easy, that the testis itself is generally readily located and removed and that controlled repair of the incision is possible. Serious post-operative complications are rare and the danger of post-operative prolapse of bowel eliminated.     

Observer variation in equine abdominal auscultation

The reliability of abdominal auscultation was investigated via an observer variation study. Clinicians listened to a variety of minute-long equine gut sound recordings. They evaluated the amount of gut sounds as 'absent', 'decreased', 'normal', or 'increased'. They subsequently evaluated the same recordings replayed in a different order. Intra- and inter-observer agreement was measured by the statistic kappa. There was significant intra-observer (kappa 0.57) agreement, but less agreement between observers (kappa 0.37). The best agreement was on the classification of sound tracks as 'absent' (intra-observer kappa 0.72 and inter-observer kappa 0.55). There was significant correlation between the clinicians' average assessment of the recordings and their acoustic energy levels. In this study abdominal noise was reliably assessed by auscultation. Standardised techniques and definitions would probably enhance the reliability of abdominal auscultation for the evaluation of gastrointestinal disease.     

Diagnostic and prognostic procedures for equine colic surgery

Evaluation of the horse with colic has always been challenging since the patient's large size precludes many of the diagnostic imaging procedures commonly used in human medicine. Diagnostic methods such as radiography, laparoscopy, endoscopy, and peritoneal fluid analysis can serve to increase the accuracy of presurgical evaluation. Prognosis in individual cases can be best predicted by careful analysis of selected clinicopathological data, physical examination findings, and surgical biopsies. However, no predictive model is 100 per cent accurate, and clinicians must continue to rely on clinical evidence and instinct and to use these diagnostic and prognostic procedures only as guides for case management.     

Perioperative antimicrobial considerations for gastrointestinal surgery of cattle

Perioperative use of antimicrobial drugs constitutes extra-label use of those drugs. Principles of therapeutic and prophylactic use of antimicrobial drugs can guide decisions about their perioperative use. Regimens currently suggested are based on those principles, theoretical information, pharmacokinetic and pharmacodynamic data, extrapolation from studies with other species, empirical data, personal bias, and experience. Controlled clinical investigations are necessary to provide objective data from which specific recommendations can be derived.     

Prognosis in equine medical and surgical colic

A retrospective study was performed on 649 horses admitted to the Clinic of Equine Internal Medicine (Utrecht University) for gastrointestinal colic. The aim of this study was to provide a better guideline for determining prognosis in horses with colic. Short- and long-term survival were evaluated, and Cox regression analysis was performed to identify the clinical and clinicopathologic variables usable to predict survival. Intestinal displacements and strangulations were the most frequently diagnosed causes of colic. Regarding the surgically treated horses, 54% were discharged and 88% of these were still alive after 1 year. In comparison, 85% of medically treated patients were discharged and 93% were still alive after 1 year. Only 4.4% of all long-term survivors did not return to the expected level of performance, and 32% suffered from recurrent colic. Duration of colic signs, heart rate, intestinal motility, skin tenting, level of pain, and gross appearance of peritoneal fluid were shown to be significantly associated with survival. White blood cell count, packed cell volume, blood pH, and color of the mucous membranes did not show any prognostic significance. Thus, clinical variables appeared to be the most relevant predictors of the outcome of gastrointestinal colic.     

Propofol compared with propofoVguaiphenesin after detornidine premedication for equine surgery

Anaesthesia using propofol alone and in combination with guaiphenesin, after detomidine premedication, was evaluated for performance of minor surgical procedures (castration and tenotomy) in horses. Twelve male horses were premedicated with 0.015 mg/kg of detomidine intravenously (iv) and divided into two groups of six. One group of horses received 2 mg/kg of propofol iv and the other group received 0.5 mg/kg of propofol mixed with 100 mg/kg of a 7.5% solution of guaiphenesin in saline iv. Induction of anaesthesia was fast and smooth in both groups. All horses were easily intubated immediately afterwards but intubation was easier in the horses which received propofol and guaiphenesin. Heart rate fell by 20% in both groups after detomidine injection, stabilising between 45 and 53 beats/minute during anaesthesia with no difference between the groups. Respiratory depression developed after detomidine injection and was slightly intensified after induction of anaesthesia. Respiratory rate was significantly lower in the propofol group (14 ± 3 breaths/minute) than with propofol/guaiphenesin (19 ± 4 breaths/minute) at five minutes after induction. Anaesthesia induced respiratory acidosis in both groups and hypoxaemia also occurred, but once the horses stood up the arterial blood oxygen partial pressure returned to basal values. Surgical time ranged between 8 and 16 minutes and with the exception of one horse in the propofol/guaiphenesin group the horses did not show signs of pain or discomfort during surgery. Recovery to standing was fast and took 26 ± 2 minutes in the propofol and 29 ± 5 minutes in the propofol/ guaiphenesin group. Most horses stood up at the first attempt with minimal ataxia. These two anaesthetic techniques appear to be useful for minor surgical procedures performed within 16 minutes of induction of anaesthesia.     

Standing abdominal surgery.

Safe, effective surgery can be performed in the standing, conscious horse using a combination of mechanical and chemical restraint. Clear indications for performing standing abdominal surgery exist, but many procedures are best performed under general anesthesia. The preferred approach involves a modified grid incision of the left paralumbar fossa. Flank celiotomy allows the surgeon to thoroughly explore the abdominal cavity, but few structures can be exteriorized, and visibility of abdominal contents is poor. Indications for standing abdominal surgery include diagnosis of abdominal masses, drainage and biopsy techniques, correction of left dorsal displacement of the large colon, and evaluation of rectal injuries, and performing loop colostomy techniques, laparoscopy, removal of retained testicles, correction of uterine torsions, surgical embryo transfer, ovariectomy in normal mares, and some experimental procedures. Standing surgical techniques are most useful and appropriate for surgical exploration, to correct uterine torsions, and to perform loop colostomy and surgical embryo transfer techniques. Perioperative antimicrobial and antiinflammatory therapy is recommended. Mild discomfort and ventral incisional swelling after surgery are expected.     

Perioperative supportive care and monitoring.

Supportive care minimizes the adverse physiologic effects of anesthesia, surgery, and preexisting disease. Monitoring detects physiologic perturbations, ensures appropriate anesthetic depth, and assesses the efficacy of supportive care. The principles of monitoring and supportive care are similar in small exotic species; however, an understanding of comparative anatomy, physiology, and pathophysiology is necessary to apply these principles.     

Standing male equine urogenital endoscopic surgery.

Standing laparoscopy in the horse was used initially as a diagnostic tool to assist in the diagnosis of a cryptorchid testicle. Now, this technique is also used for treatment of cryptorchid testicles. The focus of this article is the standing laparoscopic cryptorchidectomy, the most common laparoscopic procedure performed on the male equine urogenital tract. Advantages, disadvantages, instrumentation, and general procedure are discussed.     

Standing female equine urogenital endoscopic surgery.

Standing female urogenital endoscopic surgery is facilitated by the more dorsal location of the organs of the female reproduction tract. The most common reason for laparoscopic surgery on the female urogenital system is ovariectomy; however, the technique has been used to diagnose periparturient or reproductive diseases and to perform surgical embryo transfer. Standing surgical approaches avoid the risk and expense of general anesthesia, but these techniques are limited by the temperament and size of the patient and the availability of facilities for restraint. Owner acceptance of laparoscopic procedures is excellent. It is anticipated that standing endoscopic surgery may become the preferred technique for applicable procedures.     

Chronicle of laser usage in equine surgery

Laser is the acronym for light amplification by stimulated emission of radiation; the first laser beam was generated in 1960 and initially used for medical application in 1963. Today's modern surgical laser units produce an intensely focused light beam of uniform wavelength that interacts with a variety of biological cell types to vaporize, cut, coagulate, or shrink tissues. The resulting effect depends on the optical properties of the tissue and the wavelength, power output, spot size, and duration of laser beam application. Different lasers are suited to specific surgical tasks relative to their beam wavelength, power output, mode of operation (continuous, pulsed or superpulsed), and application (contact or noncontact) and instrumentation. The documented advantages of laser surgery over conventional surgical procedures are improved hemostasis, the ability to ablate or vaporize tissue, endoscopic access to body cavities, improved postoperative comfort, and shorter hospitalization and recovery times. By the mid-1980s, laser use in equine surgery was reported; the carbon dioxide and neodymium:yttrium-aluminum-garnet were the first models integrated into practice. The primary application of laser technology in equine surgery was for the correction of various upper-respiratory tract abnormalities and still remains the most prevalent use through endoscopy. Today, surgical lasers are used for the treatment of problems in the urinary, reproductive, and musculoskeletal systems, in addition to the skin and the eye. When we combine advances in laser technology and the practice of equine surgery, the result is clinicians better equipped to treat and manage the more difficult cases.