Case Report Extraperitoneal Incisional Abscess Formation After Colic Surgery in 3 Horses L

EQUINE VETERINARY EDUCATION / AE / MARCH 2012 109

Case Report Extraperitoneal incisional abscess formation after colic surgery in 3 horses L. M. Rubio Martínez*, N. C. Cribb and J. B. Koenig Department of Clinical Studies, Ontario Veterinary College, University of Guelph, N1G 2W1 Guelph, Ontario, Canada.

Keywords: horse; colic; surgery; incision; infection; abscess

Summary et al. 2010). Horses with wound infections typically present with gross drainage of purulent material from the wound In this article we report 3 horses that developed an associated with swelling, heat and pain around the skin extraperitoneal abscess after colic surgery at the incision incision (Mair and Smith 2005; Coomer et al. 2007). site. All 3 horses presented with nonspecific clinical signs Removal of the skin and subcutaneous sutures is usually and extraperitoneal abscess was diagnosed from performed to provide adequate drainage since the ultrasound evaluations and cytological examination of infection appears to be localised within the superficial abscess aspirates. One horse developed dehiscence of layers (Dukti and White 2008). In this study 3 cases that the incision after drainage of the abscess through the developed incisional infections in the form of an incision. In 2 cases a small standing paramedian incision extraperitoneal abscess after colic surgery are reported. was performed through which the abscess was drained Extraperitoneal abscess formation is a previously and lavaged; complete resolution of the abscess and unreported incisional complication after colic surgery in healing of the incision was achieved in both cases. horses. Extraperitoneal abscess is a previously unreported incisional complication after colic surgery in horses. Early Case 1 and careful ultrasonographic examination of the abdominal incision is required for diagnosis in cases with A 3-year-old Thoroughbred stallion with a 2 day history of a nonspecific clinical signs. A paramedian incision through complete, displaced, lateral condylar fracture of the right the rectus abdominis muscle into the abscess cavity third metacarpal bone was placed under general permitted adequate drainage and debridement of the anaesthesia and underwent surgical repair using abscess in 2 cases. arthroscopic and fluoroscopic guidance at the Ontario Veterinary College Teaching Hospital (OVCTH). The horse Introduction showed mild colic signs the day following surgical repair and rectal examination revealed a severely distended Surgical wound infection following exploratory laparotomy caecum occupying the right caudal half of the abdomen is a well recognised cause of post operative morbidity in and extending into the left side. The ventral caecal band equine colic surgery. Consequences of wound infection was extremely taut and food material and gas were include pain to the horse, further cost to the client and palpated inside the caecum. A severe caecal impaction increased risk of herniation (Gibson et al. 1989; Ingle-Fehr was diagnosed. An exploratory laparotomy was et al. 1997; French et al. 2002). Several studies have performed and caecal contents evacuated via a previously investigated the prevalence and risk factors typhlotomy. The abdomen was clipped under general predisposing horses to wound complications including anaesthesia and chlorhexidine soap used to scrub the incisional infections (Phillips and Walmsley 1993; Freeman ventral abdomen for 5 min or more until it was visibly et al. 2000; Mair and Smith 2005; Coomer et al. 2007; Torfs spotless on a clean white laparotomy sponge. This was followed by cleaning of the abdomen with ethanol, *Corresponding author email: [email protected]. Present followed by one preparation with ethanol-based address: Department of Companion Animal Studies, University of chlorhexidine gluconate followed by ethanol. Once the Pretoria. Private Bag X04 Onderstepoort 0110, Republic of South Africa. This work was presented as a poster at the 2010 European College of horse was moved into the operating theatre another Veterinary Surgeons Meeting in Helsinki, July 2010. preparation of the abdomen with ethanol-based

chlorhexidine gluconate followed by ethanol was performed. The ventral abdomen was draped following routine 4 corner double draping with an iodophor impregnated incise drape (Ioban)1 applied over the BW surgical field inbetween both draping layers. A ventral midline approach to the abdomen was performed; a No. 22 scalpel blade was used to incise the skin and subcutaneous tissue and after haemostasis was applied by coaptive electrocoagulation, the linea alba was carefully entered at the umbilical scar with a fresh No. 10 scalpel blade. The abdominal incision was extended cranially along the midline using a scalpel blade after digital Absc LC dissection of the extraperitoneal fat located dorsal to the linea alba. A sterile plastic drape was placed over the abdomen and the peritoneum opened with blunt finger dissection. After completion of the surgery, a 30 Fr abdominal drain (Mushroom drain)2 was placed Spleen approximately 10 cm lateral to the incision on the right side at the most ventral point of the abdomen. This drain was placed for post operative lavage of the abdominal cavity Fig 1: Transverse ultrasonographic image at the cranial aspect of the ventral midline incision from Case 1 (right to right). Note the as a standard procedure after typhlotomy by the large mixed heterogenic structure located dorsal to the linea alba operating surgeon. The abdominal incision was closed in a (BW: body wall; Absc: abscess; LC: large colon; Arrow: midline). simple continuous suture pattern using No. 2 polyglactin 910 (coated Vicryl)3, the subcutaneous tissue was closed in a simple continuous pattern using No. 2/0 glycomer 631 unremarkable and the horse was ambulating (Biosyn)4 and skin closed with No. 2/0 polypropylene in a comfortably on the affected limb. No swelling was simple continuous suture pattern (Surgipro)3. For recovery, evident at the ventral abdominal incision which was not sterile gauze and a fresh iodophor impregnated incise painful to the touch; however, a small amount of drape (Ioban)1 were applied over the incision. After the serosanguineous discharge was noted at the cranial horse recovered uneventfully from anaesthesia the incise aspect of the abdominal incision. An abdominal drape was removed and an abdominal bandage ultrasound examination was performed on the 8th post consisting of sterile towels over the incision held in place operative day and revealed the presence of an with roll gauze and adhesive bandage material applied. approximately 10 ¥ 10 cm large mixed heterogenic Treatment with sodium penicillin (22,000 iu/kg bwt i.v. q. structure located dorsal to the linea alba at the cranial 6 h), gentamicin (6.6 mg/kg bwt i.v. q. 24 h) and aspect of the abdominal incision (Fig 1); this was located phenylbutazone (4.4 mg/kg bwt, i.v. q. 12 h) had been cranial to the abdominal drain site. Several small started before fracture repair. This treatment was hypoechoic areas were also found just dorsal to the linea continued after colic surgery but anti-inflammatory alba at the middle part of the incision. No free fluid was therapy was substituted with flunixin meglumine (1.1 mg/kg noted within the abdomen and the intestines had normal bwt i.v., q. 12 h). After colic surgery, the stallion was also wall thickness and adequate motility. The abnormal administered heparin (40 iu/kg bwt s.c., q. 8 h), findings seemed to be separate from the abdominal metronidazole (15 mg/kg bwt, q. 6 h per rectum) and a cavity even though a distinct wall was not evident at the constant rate infusion of metoclopramide (0.04 mg/kg dorsal limits of the mass. No purulent drainage was bwt/h, i.v.). Abdominal lavages were performed with 15 l observed upon removal of part of the skin sutures. A of lactated Ringers’ solution through the abdominal drain complete blood cell count showed mild leucocytosis every 12 h during the first 24 h after surgery; after that time (11.1 ¥ 109 cells/l; ref: 5.1–11.0 ¥ 109 cells/l) with mild the drain was removed. Heparin was also discontinued mature neutrophilia (8.99 ¥ 109 cells/l; ref: 2.8–7.7 ¥ 109 after 24 h. Food was gradually reintroduced over the cells/l). No other remarkable findings were noted on following days after surgery without complications. physical examination. Findings were consistent with the formation of an abscess or organising haematoma in the Case progression extraperitoneal space. An aspirate sample was collected from the mass and cytological examination revealed the No abnormal findings were observed in the horse’s presence of mixed rods and cocci as well as a large clinical examination and demeanour during the post number of toxic neutrophils. Abdominocentesis was not operative period until the 7th post operative day when performed due to the lack of abnormal findings and free the horse developed pyrexia (40.2°C) and was quieter fluid within the rest of the abdomen. A final diagnosis of than normal. The surgical area at the fracture site was an extraperitoneal abscess was made.

the linea alba; a mushroom drain was not used in this case. Recovery from anaesthesia was uneventful and an BW abdominal bandage was not used in this case. BW Preoperatively, the horse was placed on sodium penicillin (22,000 iu/kg bwt i.v. q. 6 h), gentamicin (6.6 mg/kg bwt i.v. q. 24 h) and flunixin meglumine (1.1 mg/kg bwt i.v. q. 12 h) which were administered for 5, 6 and 4 days in total, respectively.

Case progression

Initially, good clinical progression was seen and the horse was sent home 6 days following surgery. Twelve days following surgery the horse was re-examined at the OVCTH 3.18 cm for mild colic signs of unknown aetiology which resolved without treatment. Physical examination showed no abnormal findings. No swelling was evident at the ventral Fig 2: Transverse ultrasonographic image at the cranial aspect of abdominal incision and it was not painful to the touch. A the ventral midline incision from Case 1 (right to right). Note the complete blood cell count revealed leucocytosis (17.4 ¥ separation (dotted line 3.18 cm) of both sides of the incision = 9 9 (dehiscence). BW: body wall. 10 cells/l; ref: 5.1–11.0 ¥ 10 cells/l) with mature neutrophilia (16.0 ¥ 109 cells/l; ref: 2.8–7.79 cells/l). Trimethoprim-sulphadiazine (24 mg/kg bwt per os q. 12 h) Treatment and outcome was administered for 5 days. Two days later the horse showed mild pyrexia (39.3°C) and the skin sutures were Antimicrobial therapy was changed to enrofloxacin removed. Mild oedema was noted at the incision site (7.5 mg/kg bwt per os q. 24 h) and metronidazole but no discharge or pain to the touch was present. (15 mg/kg bwt per rectum q. 6 h). Purulent material was Ultrasound examination revealed the presence of a small found draining from the cranial aspect of the incision on hypoechogenic structure between the ventral body wall the 11th post operative day. Culture results from the and peritoneal cavity at the caudal aspect of the incision aspirate sample became available and showed Klebsiella consistent with haematoma or abscess formation. Two spp. sensitive to enrofloxacin and a multi-resistant strain of days later (16th post operative day), foul-smelling Enterobacter cloacae. The following day (12th post serosanguineous fluid was observed discharging from the operative day) a large amount of purulent discharge was caudal aspect of the surgical incision. A complete blood observed draining from the cranial part of the incision. cell count revealed white blood cell and neutrophil counts Repeat ultrasound examination revealed dehiscence of had returned to normal limits. Repeat ultrasound the cranial aspect of the incision (Fig 2). The owners examination revealed a multi-loculated fluid filled structure declined further treatment and the horse was subjected to (20 cm wide, 42 cm long and 9.5 cm deep) between the euthanasia. Post mortem examination revealed the linea alba and the peritoneal cavity (Fig 3). A thin capsule presence of a 6 ¥ 8 cm extraperitoneal abscess located was present surrounding the mass and no abnormalities over the cranial part of the incision partially invading the were observed affecting the viscera. Abdominocentesis rectus abdominis muscle. The peritoneal surface over the was not performed. Placement ofa6Frdogurinary abscess was intact and a tract from the abscess catheter5 into the caudal drainage site yielded 200 ml of communicated with the cranial aspect of the incision. No similar appearing fluid which was submitted intra-abdominal adhesions or signs indicative of septic for culture and susceptibility. A diagnosis of an extra peritonitis were identified on post mortem examination. peritoneal abscess was made.

Case 2 Treatment and outcome

An 11-year-old Thoroughbred gelding underwent Rifampin (5 mg/kg bwt per os q. 12 h) was added to the ventral midline celiotomy for surgical correction antimicrobial regimen. For the following 5 days the abscess of a nephrosplenic entrapment of the large colon and was drained daily in the aforementioned manner yielding evacuation of colonic contents via a pelvic flexure between 250 and 400 ml volume each time. Enterobacter enterotomy. Preparation and draping of the ventral cloacae was isolated from the fluid and the antimicrobial abdomen, abdominal approach and closure and regimen was changed to enrofloxacin (7.5 mg/kg bwt per protection of the ventral midline incision were performed in os q. 24 h) based on susceptibility results. the same way as Case 1. The only difference was the use On the 24th post operative day a second draining tract of No. 3 polyglactin 910 (coated Vicryl)3 for the closure of at the cranial aspect of the incision developed at

Five months following the initial colic surgery the horse re-presented with acute abdominal pain. A ventral midline BW celiotomy was performed. No hernia or other ventral midline defect was noted. The large colon was entrapped between the body wall and the spleen. Extensive Absc adhesions had obliterated the nephrosplenic space and were also identified between the distal portion of the spleen and the left body wall and ventral midline of the abdomen. The large colon was resected and the abdominal incision was closed as described above. The horse fractured a leg during recovery from general anaesthesia and was subjected to euthanasia shortly thereafter. Spleen Case 3

A 13-month-old Thoroughbred colt underwent ventral Fig 3: Transverse ultrasonographic image at the caudal aspect of the ventral midline incision from Case 2 (right to right). Linea alba midline celiotomy for surgical correction of an ileocaecal appears intact with a suture loop (arrow) still visible (BW: body wall; intussusception. Preparation and draping of the ventral Absc: abscess). abdomen, abdominal approach and closure and protection of the ventral midline incision were performed approximately 10 cm from the caudal tract. Repeat similar to Case 1. The only difference was the use of No. 2 ultrasound examination revealed no improvement in the polydioxanone (PDS*II)6 for the closure of the linea alba. overall size of the abscess but a mature fibrous capsule had Recovery from anaesthesia was uneventful and an developed. Under standing sedation and ultrasound abdominal bandage was used in this case. The guidance and with the use of local anaesthesia a one intussusception could not be reduced and was left in quarter inch penrose drain6 was placed as a seaton drain place. A partial bypass of the ileocaecal valve was between the cranial and caudal draining tracts. performed through a side-to-side ileocaecostomy. The Additionally, following local infiltration analgesia with 2% horse was administered sodium penicillin (22,000 iu/kg bwt lidocaine, a 4 cm long left paramedian incision was made i.v. q. 6 h), gentamicin (6.6 mg/kg bwt i.v. q. 24 h) and into the abscess under ultrasonographic guidance. The flunixin meglumine (1.1 mg/kg bwt i.v. q. 12 h) for 7, 5 and abscess was lavaged through this incision with 1 l of a 0.25% 4 days, respectively. chlorhexidine gluconate solution. Teat cannulas7 were placed in the cranial and caudal incision sites to act as Case progression egress sites. The interior of the abscess was gently debrided with dry gauze swabs via the paramedian incision and an On the 7th post operative day, the horse developed mild abdominal bandage was placed following the procedure. pyrexia (39.7°C). A complete blood cell count at this time The drain was removed after 4 days. A complete blood cell revealed leucocytosis (14.9 ¥ 109 cells/l; ref: 5.1–11.0 ¥ 109 count at this time revealed a mild leucocytosis (12.1 ¥ 109 cells/l) with mature neutrophilia (11.47 ¥ 109 cells/l; ref: cells/l; ref: 5.1–11.0 ¥ 109 cells/l) and neutrophilia with a left 2.8–7.7 ¥ 109 cells/l). No other abnormal findings were shift (10.10 ¥ 109 cells/l; ref: 2.8–7.79 cells/l) likely due to noted on the full physical examination. The incision was not inflammation; no toxic changes were seen. Lavage, swollen or painful to palpation. Ultrasound examination did debridement and bandaging of the abscess were not show abnormal findings within the abdomen or at the continued daily in this manner for the following 20 days. incision. Due to the absence of specific findings indicating During this time the draining tracts and the left paramedian the origin of the infection, the presence of mature incision granulated and sealed. Enrofloxacin was neutrophilia and considering the original abdominal discontinued after 14 days of administration as a repeat accident and surgical procedure, an intraabdominal culture and susceptibility revealed a multi-resistant strain of abscess was suspected. Treatment with rifampin (5 mg/kg Enterobacter cloacae had evolved. No further bwt per os q. 12 h) and clarithromycin (7.5 mg/kg bwt per antimicrobials were administered. Repeat ultrasound os q. 12 h) was initiated. On the 10th post operative day, a examination on the 45th post operative day revealed small amount of serosanguineous drainage was noted at resolution of the abscess. All white blood cell parameters the middle of the abdominal incision. Repeat ultrasound were within normal limits at this time. A 4 ¥ 2 cm hernia was examination revealed an approximately 4 cm diameter noted at the site of the cranial draining tract. A hernia belt8 cavity filled with hyperechoic fluid between the was placed on the horse and remained in use for the abdominal wall and the peritoneal cavity and located to following 4 months. At this time the nephrosplenic space the right of midline (Fig 4). This cavity partially dissected into was ablated during a standing laparoscopic procedure. the dorsal aspect of the right rectus abdominis muscle and

following 4 days. Based on the culture (Escherichia coli) and susceptibility results, the antimicrobial therapy was switched to trimethoprim-sulphadiazine (25 mg/kg bwt per os q. 12 h). The amount of discharge from the abdominal BW and paramedian incisions decreased over the following 2 weeks. Another sample collected from the area during this time revealed the presence of an additional bacteria, Enterobacter agglomerans, with a slightly different sensitivity pattern. Based on these results, the antimicrobial therapy was changed to oral enrofloxacin (7.5 mg/kg bwt Absc per os q. 24 h). On the 26th post operative day, ultrasound examination revealed that the abscess had completely resolved and no signs of infection were found. Antimicrobial therapy was discontinued. Four months after surgery, ultrasonographic examination showed successful healing of the abdominal incision without the presence of herniation. Fig 4: Transverse ultrasonographic image at the cranial aspect of the ventral midline incision from Case 3 (right to right). Note cavity filled with hyperechoic material (abscess) dorsal to the linea alba; partial invasion into the dorsal aspect of the right rectus abdominis Discussion and conclusion muscle is observed (big arrows). Note the fluid line (small arrow) at the dorsal aspect of the cavity (BW: body wall; Absc: abscess; Previous studies indicate laparotomy wound infection rates asterisk: midline). range from 7.4–37% (Phillips and Walmsley 1993; Freeman et al. 2000; Mair and Smith 2005; Coomer et al. 2007). At our institution, 1506 horses were recovered from anaesthesia after colic surgery from 1994–2008 and 188 (12.5%) of those horses developed incisional infection (J.B. Koenig, unpublished data). These are the only 3 cases diagnosed BW with extraperitoneal abscess formation after colic surgery at our institution during that time. Ultrasonographic examination of the incision site was necessary for diagnosis and such use of this imaging modality has become Absc standard practice at our institution in horses that develop incisional drainage, colic, systemic mature neutrophilia or a fever after surgery for colic. However, the use of ultrasound was not used in a standardised manner during that time. Although inclusion criteria differ among studies, wound LC infection can be defined as presence of gross drainage of purulent material from the wound associated with swelling, Fig 5: Transverse ultrasonographic image at the cranial aspect of the ventral midline incision from Case 3, slightly cranial to Figure 4 heat and pain around the skin incision (Mair and Smith (right to right). Note the presence of a suture loop (arrow) within the 2005; Coomer et al. 2007). However, it has been suggested abscess (BW: body wall; Absc: abscess; LC: large colon). that any form of drainage from the celiotomy incision should be considered to be indicative of incisional involved one loop of the linea alba suture (Fig 5). Skin infection (Smith et al. 2007). The presence of purulent sutures were partially removed but no drainage from drainage could just be representing a later stage of a that cavity could be achieved. A diagnosis of an subclinical wound infection. In Cases 1 and 2 of this report, extraperitoneal abscess was made. purulent wound drainage was evident only at the end point of a chronic severe infection localised adjacent to Treatment and outcome the linea alba (Case 2) or when serious complications such as wound dehiscence were already occurring (Case 1). In Under standing sedation, ultrasound guidance and local Case 3, there was no gross drainage of purulent material anaesthesia, a 2 cm long right paramedian incision was from the wound even though a severe infection was made into the cavity and approximately 30 ml of thick already present. Therefore, incisional infections can occur purulent material drained. The incision and the abscess without purulent drainage being present at the incision cavity were lavaged with 0.25% chlorhexidine gluconate site. To the authors’ knowledge, post surgical abdominal solution by using a teat cannula once daily over the incisional infection in the form of an intraparietal (located

inside the abdominal wall) extraperitoneal abscess has not monitoring (Cases 2 and 3). Ultrasound examination is been previously reported. Due to the restricted number of routinely used at our institution to examine the abdominal cases it is difficult to speculate on potential factors incision in post surgical colic cases with fever, swelling, or involved in the development of extra peritoneal abscesses. pain at the incision site, even in the absence of incisional Based on previous studies, it seems that contamination drainage. The authors believe that placement of an leading to the development of an infection of the ultrasonographic probe over the abdominal incision site abdominal incision mainly occurs in the early post does not increase the incidence of incisional infection operative period (Galuppo et al. 1999). The 3 horses providing it is performed using a sterile technique. included in this study had the incision covered during Drainage should be established when an incisional recovery from anaesthesia to prevent environmental infection occurs. Removal of adjacent skin sutures is the contamination of the incision site. In addition, the skin was usual method for infections localised within subcutaneous closed with polypropylene in a simple continuous suture tissue and skin (Dukti and White 2008). However, for Cases pattern which is associated with a lower incidence of 2 and 3, partial removal of the skin sutures was not enough incisional infections than skin closure with staples (Torfs (Case 2) or was not at all effective (Case 3). Instead, a et al. 2010). Bandaging of the abdominal incision in the paramedian incision provided better drainage in both of post operative period was employed in 2 of the 3 cases these cases and also permitted debridement of the and this practice reduced the risk of abdominal incisional abscess cavity. In addition, establishing drainage through infection (Smith et al. 2007). In all 3 cases, the intestinal a paramedian incision may have prevented draining lumen was opened during surgery and therefore tracts from developing within the incision, further contamination with intestinal contents may have jeopardising its healing. In Case 3, a suture loop was occurred. However, the importance of intraoperative evident within the cavity of the abscess and after drainage exposure to faecal content as a risk factor for incisional of the abscess, the incision healed without any further infections is controversial (Mair and Smith 2005; Coomer complications such as herniation. In Case 1, a paramedian et al. 2007; Torfs et al. 2010). Dissection of the incision was not performed because no distinct wall was subcutaneous tissues to facilitate closure of the linea alba observed in the ultrasound examination. However, in is not performed by the authors but digital dissection of the retrospect, a paramedian incision might have provided extra peritoneal fat was performed in these cases. It is adequate drainage of the abscess preventing incisional possible that the presence of seroma or haematoma in the dehiscence. Incisional infection is strongly associated with extra peritoneal space may be involved in the hernia formation (French et al. 2002) and 2 of the 3 cases development of this type of incisional infection in horses. (66%) reported here developed incisional herniation. This This speculation is supported by the observation the represents a higher incidence than previously reported infection does not seem to originate in the cutaneous or after infection of abdominal incisions (Gibson et al. 1989; subcutaneous space. Ingle-Fehr et al. 1997; French et al. 2002). The 2 cases that Ultrasonography is a readily available diagnostic developed hernias in this study showed draining tracts technique in most equine clinics with surgical facilities and traversing the whole thickness of the linea alba. Although for many ambulatory practitioners. Ultrasound examination this observation is made from only 3 animals, we speculate of the abdominal incision was required for the diagnosis of the disruption of the incisional healing may be greater in the extra peritoneal abscesses in these 3 horses in the cases with extraperitoneal abscesses and draining tracts absence of specific external signs of incisional infection. through the incision compared to those cases with Although only confirmed by post mortem examination in infections localised in the cutaneous and subcutaneous Case 1, it provided good assessment of the location and layers of the incision. The authors believe that drainage extensiveness of the abscesses. In Case 2, the abscess through a paramedian incision may help prevent draining formed a thick capsule around the cavity at the peritoneal tracks from forming through the incision. surface which was readily evident ultrasonographically. In Adequate antimicrobial penetration into the abscess is Cases 1 and 3, a distinct abscess capsule was not evident always a concern; some antimicrobials do not penetrate but ultrasound findings suggested that the infection was the thick abscess wall or may not be as effective in the localised based on the absence of findings indicative of presence of purulent material (Bergamini and Polk 1989). septic peritonitis. Evaluation of abdominal fluid may have Also, antimicrobials available in equine practice to treat confirmed the presumed absence of septic peritonitis but it multi-resistant infections can be limited. Effective drainage was not considered necessary based on ultrasonographic of accumulated infected material is important for the findings and, in addition, abdominocentesis posed a effective treatment of infections, especially those with significant risk for contamination of the abdominal cavity. abundant accumulation of material or multi-resistant Post mortem examination confirmed the extra peritoneal aetiological organisms. A paramedian incision was easy to location of the abscess in Case 1. Ultrasound examination perform on the horse standing; it also provided a route to also provided adequate guidance for safe aspiration of lavage the abscess cavity with antiseptic solution, which abscess content (Cases 1 and 3), determining landmarks can be very advantageous in cases of multi-resistant for the paramedian approach and post operative infections where no antimicrobials are available. The use of

systemic and local antimicrobials is controversial but is Coomer, R.P., Mair, T.S., Edwards, G.B. and Proudman, C.J. (2007) Do often recommended if the horse is systemically affected subcutaneous sutures increase risk of laparotomy wound suppuration? Equine vet. J. 39, 396-399. (i.e. fever) after drainage has been established or if moderate to severe inflammation or oedema is present at Dukti, S. and White, N. (2008) Surgical complications of colic surgery. Vet. Clin. N. Am.: Equine Pract. 24, 515-534. the surgical site (Hardy and Rakestraw 2006). Systemic antimicrobials might not be required in cases with Freeman, D.E., Hammock, P., Baker, G.J., Goetz, T., Foreman, J.H., Schaeffer, D.J., Richter, R.A., Inoue, O. and Magid, J.H. (2000) extraperitoneal abscesses after establishing drainage, Short- and long-term survival and prevalence of postoperative ileus as shown by successful healing after discontinuing after small intestinal surgery in the horse. Equine vet. J., Suppl. 32, antimicrobial therapy in Case 2. 42-51. In conclusion, intraparietal extra peritoneal abscess at French, N.P., Smith, J., Edwards, G.B. and Proudman, C.J. (2002) Equine the incision site appears to be a rare incisional surgical colic: risk factors for postoperative complications. Equine complication after colic surgery in horses in which vet. J. 34, 444-449. occurrence and management has not been previously Galuppo, L.D., Pascoe, J.R., Jang, S.S., Willits, N.H. and Greenman, S.L. reported. Early and regular ultrasonographic examination (1999) Evaluation of iodophor skin preparation techniques and factors influencing drainage from ventral midline incisions in horses. of the abdominal incision is required for adequate J. Am. vet. med. Ass. 215, 963-969. diagnosis in cases with nonspecific clinical signs. A Gibson, K.T., Curtis, C.R., Turner, A.S., McIlwraith, C.W., Aanes, W.A. and paramedian incision through the rectus abdominis muscle Stashak, T.S. (1989) Incisional hernias in the horse. Incidence and into the abscess cavity provided adequate drainage and predisposing factors. Vet. Surg. 18, 360-366. access for debridement of the abscesses in these cases. Hardy, J. and Rakestraw, P.C. (2006) Postoperative care and complications associated with abdominal surgery. In: Equine Authors’ declaration of interests Surgery, 3rd edn., Eds: J.A. Auer and J.A. Stick, Saunders Elsevier, St Louis. pp 506-509. No conflicts of interest have been declared. Ingle-Fehr, J.E., Baxter, G.M., Howard, R.D., Trotter, G.W. and Stashak, T.S. (1997) Bacterial culturing of ventral median celiotomies for prediction of postoperative incisional complications in horses. Vet. Manufacturers’ addresses Surg. 26, 7-13.

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