44


EQUINE VETERINARY EDUCATION / AE / JANUARY 2020


Laparoscopic repair of incisional hernias has been


described (Rijkenhuizen 2005; Caron and Mehler 2009); reported advantages included a broad exposure of the hernia and definition of the hernia margins, a reduced risk of infection due to its less invasive character, the potential for surgery to be performed earlier as incision portals are further away from the defect and its surrounding oedematous tissue (Rijkenhuizen 2005) and the ability to identify and transect adhesions if present (Caron and Mehler 2009). This technique will likely require further evaluation in the cases of abdominal wall tearing, but is likely to gain increasing popularity. Although a large number of reports describing incisional


and traumatic hernia repairs exist, few reports specifically describe surgical repair of abdominal wall tearing in mares (Meek et al. 1977). It should be remembered that many hernias do not require surgical repair (Freeman 2005). Hernia repair is also not without risks, including chronic colic, incisional drainage, implant infection and further muscle tearing (Freeman 2005). Long-term survival rates varying from 50% (Elce et al. 2005) to 92% (Davis and Rakestraw 2002; Whitfield-Cargile et al. 2011) are reported. Potentially, it is difficult to justify the surgical repair in mares, in which many can foal successfully with abdominal wall defects. Surgical repair however, is indicated in those cases in which one is suspicious that a large hernia may be lead to complete rupture of the abdominal wall (Freeman 2005). Rupture of the prepubic tendon in the mare is not a


surgical condition, in contrast to small animals. Repair of prepubic tendon rupture (often secondary to blunt trauma) in dogs is commonly reported (Smeak 2014). Techniques include reattachment of the anatomical musculature with direct suture, re-attachment of the ligament with sutures placed through holes drilled in the pubis; with or without the use of prosthetic mesh and the use of muscle flaps from sartorius muscle (Smeak 2014) or the rectus abdominis (Archipow and Lanz 2011). These techniques in the dog seem to have a high success rate with a relatively low risk (15%) of recurrence (Smeak 2014). In contrast, surgical repair of the prepubic tendon has not been documented in the horse. It is likely that no repair would have sufficient strength given the considerable tension of the ventrolateral abdominal wall in the horse. In summary, many mares with abdominal wall defects


can successfully carry further pregnancies, and foal successfully, with assistance. The clinician should decide on a case by case basis whether re-breeding is appropriate. If a bona fide PPT rupture is suspected, re-breeding and carrying a foal to term is not advisable. Retirement from breeding or assisted reproductive techniques such as embryo transfer is recommended in appropriate breeds.


Prognosis


The condition can prove fatal to the mare for a number of reasons. Evisceration may occur, either prior to parturition, as a result of skin necrosis (as seen by this author), or during parturition (LeBlanc 2007). Catastrophic body wall rupture can lead to the mare’s abdomen reaching the ground (A. O. McKinnon, personal communication). Rupture of a gastrointestinal viscus may occur, or incarceration of gastrointestinal viscera through a tear in the body wall may ensue. Finally, fatal haemorrhage may occur as the uterus loses the support of the body wall. One case report has also


© 2018 EVJ Ltd


documented spinal cord trauma necessitating euthanasia (Hendriks et al. 2007). Survival rates of both mare and foal vary greatly between


published reports. One older study presented four mares; in this all four foals and three mares died; the surviving mare died 6 months later (Hanson and Todhunter 1986). A larger more recent study (13 mares) demonstrated survival in 10/13 mares (Ross et al. 2008). The number of foals surviving is not clearly recorded but said to be good. This group found that foal survival was significantly better in the conservatively managed mares vs. those with intervention. It is also interesting that the group found foal survival was not significantly affected by gestational age, or type of body wall defect, although only three of 13 cases appear to involve the PPT. One recent case report (Schutten 2016) reports successful foaling of a conservatively managed Standardbred mare with a complete PPT rupture. Our clinical experience and that of others (Santschi and Vaala 2011) would suggest that mares with complete rupture of the PPT carry a poor prognosis. Logically, foals of a lower gestational age will have a more guarded prognosis for survival. It would appear that room exists within the literature for a


larger multi-centre case series documenting the outcome of these cases. Perhaps our increasing abilities to monitor fetal viability and fetal well being, to control the condition of these mares with more sophisticated multimodal analgesic regimes, or our increasing proficiency at managing the high risk neonate mean that survival of these foals and their dams can improve the prognosis for this condition from the previously disastrous condition it has been historically.


Author’s declaration of interests No conflicts of interest have been declared.


Ethical animal research Not applicable to this review article.


Source of funding None.


Acknowledgements


The author thanks Dr Angus McKinnon for providing Fig 5 and reviewing the manuscript.


Manufacturers' addresses 1BSN medical Australia and New Zealand, Mount Waverley, Victoria,


Australia. 2CM Equine Products, Norco, California, USA. 3Kruuse UK Ltd., Sherburn In Elmet, North Yorkshire, UK.


References


Archipow, W. and Lanz, O.I. (2011) Rectus abdominis muscle flap for repair of prepubic tendon rupture in 8 dogs. Can. Vet. J. 52, 1215- 1218.


Canisso, I.F., Ball, B.A., Troedsson, M.H., Silva, E.S. and Davolli, G.M. (2013) Decreasing pH of mammary gland secretions is associated with parturition and is correlated with electrolyte concentrations in prefoaling mares. Vet. Rec. 173, 218.


Continued on page 48


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76