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porting the use of colloids have been withdrawn.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
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