Using acellular aortic matrix to repair umbilical hernias of calves V Kumar,* N Kumar, AK Gangwar and AC Saxena Background Umbilical hernias are a relatively common, possibly hereditary, condition in calves. Acellular aortic matrix (AAM) was evaluated for the repair of umbilical hernias in nine calves. Methods Fresh buffalo aorta to be used as a graft was decellular- ised using 1% sodium dodecyl sulfate and 0.25% trypsin. Under xylazine sedation and local analgesia, the hernial ring was exposed and repaired with the AAM graft using an inlay technique. Results All animals had an uneventful recovery without clinical signs of wound dehiscence, infection or recurrence of hernias during the 6-month follow-up period. Conclusion AAM of buffalo origin has adequate strength to be used safely for the repair of umbilical hernias in calves. Keywords acellular aortic matrix; buffalo; calves; decellularisa- tion; umbilical hernia Abbreviations AAM, acellular aortic matrix; PBS, phosphate- buffered saline; SDS, sodium dodecyl sulfate Aust Vet J 2013;91:251–253 doi: 10.1111/avj.12058 U mbilical hernias are fairly common in calves. 1 The condition is considered to be hereditary and most commonly occurs in the Holstein-Friesian breed. 2 It is the result of incomplete closure of the umbilicus at birth, because of maldevelopment or hypo- plasia of the abdominal muscles, 3 and the only effective treatment is surgery to restore the integrity of the abdominal wall and prevent incarceration and strangulation of herniated contents. 4 Tight suturing to approximate and close the defect can lead to wound dehiscence, recurrent hernias and non-healing of the wound. 4 The use of non- absorbable, synthetic mesh material has been reported to cause com- plications such as mesh extrusion, bowel adherence, fistula formation, wound infection, skin erosion and seroma development. 5 To over- come the disadvantages of synthetic meshes, biomaterials may be preferable for the surgical repair of hernias. 6 Biomaterials have distinct advantages over synthetic meshes for the repair of hernias, because of their ability to become vascularised and remodelled into autologous tissue, and to resist infection. 7 However, in their native form, biomaterials tend to be immunogenic and hence are decellularised to minimise their immunogenicity. 8 Acellular aortic matrix (AAM) of porcine origin has been used successfully for the reconstruction of abdominal wall defects in rats. 6 An in vivo biocom- patibility evaluation of AAM of buffalo origin in a guinea pig model revealed biocompatibility 9 and so the present study was undertaken to evaluate its efficacy for the repair of umbilical hernias in calves. Materials and methods Animals The present study was conducted on nine client-owned calves that were presented to the Surgery Unit of the Referral Veterinary Poly- clinics, Indian Veterinary Research Institute, Izatnagar, Uttar Pradesh, India. The calves were female and either crossbred Holstein-Friesian (n = 7) or undefined breed (n = 2). The age of the calves ranged from 1 to 11 months (mean, 4.56 months). Physical examination in each case revealed a painless, reducible soft swelling with a discernible ring at the umbilicus (Figure 1), diagnosed as congenital umbilical hernia. At the time of presentation, the animals’ heart and respiratory rates and temperatures were within normal reference ranges. Preparation of AAM Nine fresh aortas of buffalo origin (Bubalus bubalis) were collected from the local abattoir and immediately preserved in ice-cold (4°C) sterile phosphate-buffered saline (PBS) (pH 7.4) containing amikacin (1 mg/mL) and a proteolytic inhibitor (0.2025% EDTA). Each aorta was washed thoroughly with sterile PBS to remove all adherent blood and debris, then decellularised using 1% sodium dodecyl sulfate (SDS) for 24 h followed by treatment with 0.25% trypsin for 2 h and 1% SDS for a further 24 h, during continuous agitation in a hori- zontal orbital shaker (180 rotations/min). The acellularity of the prepared matrix was confirmed microscopically using haematoxylin and eosin staining. The prepared AAM was then washed six times (2 h each) with sterile PBS on an orbital shaker to remove residual chemicals and stored in PBS solution containing 0.1% amikacin at –20°C until use. *Corresponding author. Division of Surgery, Indian Veterinary Research Institute, Izatnagar-243122, Uttar Pradesh, India; bharadwaj374@gmail.com Figure 1. Preoperative appearance of an umbilical hernia in a female Holstein-Friesian calf. PRODUCTION ANIMALS PRODUCTION ANIMALS © 2013 The Authors Australian Veterinary Journal © 2013 Australian Veterinary Association Australian Veterinary Journal Volume 91, No 6, June 2013 251