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Clinical Commentary Colic in the equine neonate: Not your typical cause of colic and are we doing better with treatment? L. L. Southwood Department of Clinical Studies, New Bolton Center, University of Pennsylvania, 382 West Street Rd, Kennett Square, Pennsylvania, USA.

Keywords: ; colic; foal; laparotomy; celiotomy; gastrointestinal

Introduction can lead to intestinal intussusception or volvulus necessitating surgical intervention. Surgery is also indicated Colic in the equine neonate can be challenging to in some cases as a diagnostic tool. Retrospective studies on diagnose and successfully manage. Many of the common foals undergoing have reported the causes of colic in neonates such as meconium impaction most common findings in foals <15 days of age to be and enteritis can be treated medically and can be nonstrangulating obstruction (50%) and (30%; difficult to differentiate from a surgical lesion. Further, the Santschi et al. 2000) or enteritis (45%) and small colon clinical course can be complicated by, for example, obstruction (25%; Adams et al. 1988). The most common enteritis leading to an intussusception or volvulus reasons for abdominal surgery in foals <3 months of age necessitating surgical correction. Neonates presenting were: uroperitoneum (25%), meconium impaction (15%), with colic often have concurrent critical illness and this in enteritis (11%) and intestinal herniation (inguinal, scrotal, combination with the purported risk of and diaphragmatic) (11%; Cable et al. 1997). formation, unknown long-term outcome and economical Congenital defects are considerably less common, but considerations can add to the difficulty in making the should be considered in the neonate showing signs of decision for surgical intervention and in some cases can colic. Congenital gastrointestinal abnormalities include lead to a delay in surgical correction of the lesion. Cable malrotation, duplication, or atresia, and et al. (1997) reported a strong trend toward foals with a diverticulum (Ciftci et al. 1998). Congenital conditions that longer duration of clinical signs having a poorer survival, cause colic in the neonate include intestinal atresia (Slovis emphasising the importance of early surgical intervention 2003) or ileocolonic agangliosis or overo lethal white foal when necessary. Although not your typical cause of syndrome (Parry 2005), which cause a complete neonatal colic, the case of intestinal malrotation and mechanical or functional obstruction. While congenital congenital diverticula formation reported by Dahlberg gastrointestinal abnormalities are, by definition, present at et al. (2009) is an interesting case of colic in the equine birth they are often asymptomatic if they do not cause a neonate necessitating emergency abdominal surgery and complete obstruction. Despite the gastrointestinal a favourable long-term outcome. nonrotation in the foal reported by Dahlberg et al. (2009), congenital diverticula formation appeared to be the Causes of colic in the equine neonate actual cause of colic in this foal. Congenital diverticula are an anomaly similar to other intestinal duplications and as Various definitions of neonate have been used in reports on the authors described can be associated with multiple causes of colic in foals. Ages have ranged from <14 days congenital anomalies. While most diverticula are (Adams et al. 1988; Santschi et al. 2000) to <3 months subclinical, acute signs are associated with obstruction (Cable et al. 1997). Common causes of colic vary with the (acute or chronic impaction, formation, volvulus, age of the foal as they do with adult . Probably the intussusception or functional obstruction), haemorrhage most common causes of colic in the foal <14 days of age (ulceration, inflammation, trauma, irritation or congenital are meconium impaction, enterocolitis associated with arteriovenous malformation) or perforation (acute perfringens (East et al. 1998) and or necrotising , blunt trauma, foreign body enterocolitis as part of the hypoxic-ischaemic syndrome impaction) (Assenza et al. 2007). The diverticulum in the (Slovis 2003). These tend to be medically-managed case described by Dahlberg et al. (2009) caused an problems; however, it is important to recognise that enteritis obstruction leading to the acute signs of pain. 514 EQUINE VETERINARY EDUCATION / AE / october 2009

The decision for surgery and Livesey 1997). Often the number of neonates in these studies may be too small to identify a significant difference The decision for surgery is similar to that for mature horses between groups. Although there are no data to support or and, as in the case reported by Dahlberg et al. (2009), is refute this, it is this author’s impression that we do have a based on persistence or severity and a higher incidence of complications associated with post lack of response to medical therapy. Severe abdominal operative intra-abdominal adhesion formation following distention is also an indication for surgery. It is not abdominal surgery, particularly for gastrointestinal disease, uncommon, however, to have surgery delayed in the in neonates compared to mature horses. In the case neonate for the reasons discussed previously because it reported by Dahlberg et al. (2009), the post operative reflux can be difficult to differentiate ileus from a mechanical during hospitalisation may have been associated with a obstruction (Cable et al. 1997). Ultrasonography and functional obstruction; however, regardless of the cause, a radiography are often used in foals to obtain a tentative lack of intestinal motility may predispose to adhesion diagnosis (e.g. intussusception) and findings using these formation. The mild and brief episodes of colic following imaging modalities can be used to determine the need for hospital discharge may have been associated with some surgery (Neal 2003). adhesion formation. Early surgical intervention and meticulous surgical What makes colic surgery in the neonate technique are the most critical aspects of management for challenging? adhesion prevention. However, despite this adhesions still pose a problem in these patients. Probably the safest and Neonatal abdominal surgery is one of the most most efficacious adhesion prevention methods for challenging tests of soft tissue skills in equine surgery. Not foals include: 1) perioperative antimicrobial and only is everything obviously smaller, but the and anti-inflammatory drugs (Sullins et al. 2004); blood vessels in particular are more easily damaged 2) carboxymethylcellulose (CMC) (Mueller et al. 2000); compared to adult horses. Subjectively, the intestine 3) CMC-hyaluronate membrane (Seprafilm)1 applied to becomes inflamed quickly and with less manipulation than the site (Mueller et al. 2000); that of the adult horse. In cases with pre-existing peritoneal 4) dimethylsulphoxide (20 mg/kg bwt diluted in 500 ml inflammation associated with ischaemic intestine for saline i.v. every 12 h for 48–72 h) (Sullins et al. 2004); and 5) example or a prolonged surgical time, fibrin accumulation recently the use of intraperitoneal fucoidan solution was with formation of fibrinous adhesions can occur even shown to be efficacious for adhesion prevention in a foal during surgery. Probably in no other instance is meticulous jejunal abrasion model (Yarmout et al. 2007) and safe for surgical technique and a short duration of surgery more intraperitoneal use (Morello et al. 2009a,b). Some surgeons important to prevent post operative complications. recommend omentectomy for prevention of omental adhesions (Santschi et al. 2000). While keeping the intestine Post operative intra-abdominal adhesions moist and lavaging to remove any gross contamination is important for adhesion prevention, instillation of Whether or not equine neonates are more prone to medications into the peritoneal cavity should be avoided adhesion formation compared to their mature adult unless previously shown not to cause adhesions, septic counterparts is still debated. In an experimental study, foals in a clean-contaminated model, or impair younger than 30-days-old were more likely to develop anastomosis or body wall healing. Intraperitoneal adhesions from even minimal intestinal manipulation antimicrobials were associated with a higher survival but compared with foals older than 30 days (Lundin et al. actually increased adhesion formation compared to saline 1989). It is important to recognise that adhesions can be in a rabbit septic peritonitis model (Sortini et al. 2006). subclinical or associated with only mild intermittent signs of Instillation of a commercial CMC preparation was shown to abdominal pain. Cable et al. (1997) reported that 33% of actually increase adhesion formation (Klohnen et al. 2008) foals (age <1 year) examined after abdominal surgery had emphasising the importance of taking care with intra-abdominal adhesions and adhesions caused a intraperitoneal instillation of medications or devices. Care clinical problem in 19% of foals. Sucklings (16 days to should also be taken with the use of systemic medications, 5.9 months) were reported to form adhesions more such as , in the neonate. frequently (21%) than yearlings (12–23.9 months, 3.6%) and weanlings (6–11.9 months, 3.5%) (Santschi et al. 2000). While Long-term outcome following colic surgery there was no difference in adhesion formation between neonates and other age groups in the latter study, there Vatistas et al. (1996) reported that only 10% of foals aged were only 16 neonates that underwent exploratory <14 days survived to maturity following abdominal surgery! celiotomy. On the other hand, although 10% of horses Fortunately other retrospective studies around the same aged <2 years died of complications associated with post time reported higher survival rates with 35% of neonates operative intraperitoneal adhesions, there was no undergoing abdominal surgery surviving 6 months (Adams association between age and adhesion formation (Singer et al. 1988) and 50% of foals with meconium impaction EQUINE VETERINARY EDUCATION / AE / october 2009 515

surviving to become athletes (Hughes et al. 1993). Short- Dahlberg, J.A., Adam, E.N., Palmer, J.E. and Parente, E.J. (2009) term survival rates were obviously higher; however, Gastrointestinal nonrotation in a neonatal foal. Equine vet. Educ. 21, 508-512. particularly in foals, long-term survival and the ability of the East, L.M., Savage, C.J., Traub-Dargatz, J.L., Dickinson, C.E. and Ellis, R.P. horse to reach its athletic potential is more meaningful. (1998) Enterocolitis associated with infection Encouragingly, Cable et al. 1997 reported an in neonatal foals: 54 cases (1988-1997). J. Am. vet. med. Ass. 212, improvement in short- and long-term survival of foals aged 1751-1756. <1 year undergoing abdominal surgery from the early Klohnen, A., Sonis, J., Reffetto, J. and Bischofberger, A. (2008) Adhesion 1980’s (~35% and 15%, respectively) to 1994 (~98% and formation rate after exploratory celiotomies in horses with and 74%, respectively). More recently, Santschi et al. (2000) without intra-abdominal use sodium carboxymethylcellullose: a 4 year study. In: Proceedings of the 2008 ACVS Veterinary reported that 56% of neonates (<14 days old) that Symposium, San Diego. underwent exploratory celiotomy and 75% that were Lundin, C., Sullins, K.E., White, N.A., Clem, M.F., Debowes, R.M. and discharged alive from the hospital raced. Abdominal Pfeiffer, C.A. (1989) Induction of peritoneal adhesions with small surgery as a juvenile did impact the horse’s ability for intestinal ischaemia and distention in the foal. Equine vet. J. 21, athletic performance negatively compared to their 451-458. siblings (although sibling performance may have been Morello, S., Southwood, L.L., Slack, J., Crack, A. and Springate, C.M.K. inflated); however, once racing they performed as well as (2009a) Safety of intraperitoneal fucoidan solution in healthy adult horses undergoing exploratory celiotomy and jejunojejunostomy: their siblings (Santschi et al. 2000). Clinical findings. In: Proceedings of the 10th Meeting of European While there was no association between lesion location College of Veterinary Surgeons, Nantes. p 184. and survival, foals with a strangulating obstruction or Morello, S., Southwood, L.L., Engiles, J., Crack, A. and Springate, C.M.K. requiring resection and anastomosis had a lower survival (2009b) Safety of intraperitoneal fucoidan solution in healthy adult compared to foals with a simple obstruction or those not horses undergoing exploratory celiotomy and jejunojejunostomy: requiring resection and anastomosis (Vatistas et al. 1996; findings. In: Proceedings of the 10th Meeting of the European College of Veterinary Surgeons, Nantes. p 143. Cable et al. 1997; Santschi et al. 2000). In the study by Mueller, P.O.E., Harmon, B.G., Hay, W.P. and Amoroso, L.M. (2000) Santschi et al. 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