46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
108
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Considered baseline drug class for standing sedation, but needs to be
combined with other agents to: (1) lower the required dose, (2) improve
analgesia and (3) minimise the negative effects the combined drugs.
Tip when using this class of drug: Wait for maximum onset of action before
disturbing the horse! Adrenaline and increased sympathetic tone will
decrease the efficacy of sedation in horses. Thus, make sure your timing is
appropriate.
All drugs in this class should, ideally, be bolused followed by a constant rate
infusion (for long procedures). If the initial bolus does not provide the
required level of sedation, then consider administering a follow-up bolus to
achieve the desired level of sedation. Achieving the desired level of sedation
before commencing a procedure will ensure a more stable sedation without
the seesaw phenomenon.
Opioids:
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Do not cause any sedation in horses, may not even decrease the amount of
α2-adrenoreceptor agonists required.
Provide excellent analgesia for dull throbbing pains.
Considered essential to include in all surgical procedures.
Butorphanol (Ringer et al. 2012a, Ringer et al. 2012b, Latimer et al. 2002,
Clarke et al. 1991, Wilson et al. 2002), morphine and buprenorphine (Taylor
et al. 2013) have been used in combination with α2-adrenoreceptor agonists
with great success.
May cause increased respiratory depression in combination with α2adrenoreceptor agonists. Oxygen insufflation via nasal intubation is usually
adequate to overcome the hypoventilation.
Best to bolus initial dose followed by a constant rate infusion.
Overdose may cause increased locomotor behavioural disorders (Tranquilli
et al. 2007, Hall et al. 2001).
Morphine has been administered via the epidural route to provide prolonged
analgesia.
Local anaesthetics:
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Lidocaine has been used as a visceral analgesic (laparoscopy) and as a
prokinetic to buffer the effects of the α2-adrenoreceptor agonists and opioids
on gastrointestinal motility. It may play an effective role in prolonged standing
sedation.
Bolusing or bolus followed by a constant rate infusion may be used. Boluses
doses (0.5 to 1 mg/kg) and infusion rates (0.5 to 1 mg/kg/hr) have not been
studied in combination with constant rate infusion used for standing sedation.
However, they have been used in various clinical cases with success. The
effect may be anecdotal within this context.
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