Equine Health Update EHU Vol 19 Issue 3 - Page 30

EQUINE | Proceedings The evidence in human medicine has swung away from colloids such as hetastarch. Many of the studies sup- porting the use of colloids have been withdrawn. Col- loids can be used in the treatment of hypovolaemia in the horse, and they are much cheaper than plasma. We do use pentastarch on a regular basis, particularly to maintain blood pressure during anaesthesia of a critical case, typically a colon torsion. Plasma There are remarkably few references on the use of plasma in the critical colic case. In the UK fresh frozen plasma is commercially available, and we use it regularly in the colic case. It can be used as a treatment for en- dotoxaemia. We will treat most endotoxic horses with 1 - 2 l of plasma. Plasma really makes a difference in hypoproteinaemia. It is possible to measure oncotic pressure (meters are about £2000) but in the meantime total protein levels are a reasonable indicator of oncotic pressure. Levels of less than 40 g/l are best treated with plasma - 1g/l increase for each litre, so its 5 - 10 l a go. It is quite normal for protein levels to fall this low in horses with severe diarrhoea, and following surgery for a colon torsion. We defrost 5 l of plasma intra-operatively with colon torsions, and administer it once the horse has re- covered. Evidence for the efficacy of this treatment is lacking. However, as surgeons, you have keenly devel- oped observational skills, and you will have noticed that plasma is the same colour as gold. This is because it is the winners treatment, and because it costs the same… Antibiotics Following colic surgery horses do not need antibiotic treatment for weeks. Following a simple displacement 24 hours treatment is quite adequate, and the evidence is pretty clear that beyond 48 hours treatment is seldom necessary {Freeman:2012vw}. Horses treated prophy- lactically with antimicrobials for 72 h did not have a significantly higher infection rate compared with horses treated for 120 h, indicating that a longer duration of 30 antibiotic use is unnecessary [9]. The micro biome of the colon is very important and interfering with it is not help- ful. Antibiotics should be administered 30 - 60 minutes before the first skin incision, and re-dosed if the dura- tion of the surgery exceeds two half lives (40 minute half life for sodium penicillin). Even in an emergency situa- tion, it is very easy to give antibiotics too soon [10]. We administer procaine penicillin and gentamicin (8.8mg/ kg) in anaesthetic induction. Due to the long half life of procaine penicillin we do not re-dose with antibiotics. Steroids Corticosteroids are controversial drugs. We have no- ticed that horses treated with corticosteroids by refer- ring vets do not invariably get laminitis, and many sur- vive despite serious disease. It is recognised that post operative ileus is an inflammatory disease, associated with a massive influx of neutrophils into the small in- testine in humans. We reasoned that corticosteroids may limit this migration, and now treat surgical colic cases with a single-dose of dexamethasone (0.1mg/kg i.v.) intra-operatively and have recorded 66 horses. For comparison, data was also collected from horses under- going small intestinal colic surgery that did not receive dexamethasone, matching for resection status and type. Logistic regression was used to describe the association between dexamethasone use and POI. The overall in- cidence of POI was 28.8% (95% CI 21.8-37.0%). After adjusting for lactate status, the odds of POI was lower in horses that received dexamethasone compared to those that did not receive dexamethasone (OR 0.423, 95% CI 0.18-0.99). There was no difference in the odds of survival between horses receiving dexamethasone and those that did not (OR 1.29, 95% CI 0.47-3.54). No difference was observed in the odds of incisional in- fection between horses receiving dexamethasone and those that did not (OR 0.56, 95% CI 0.82-1.57). We have concluded that a single dose of dexametha- sone appears to reduce the incidence of POI in horses • Equine Health Update •