Intravenous anaesthesia with
propofol and fentanyl in dogs
Valentina Andreoni and Lynne
Hughes, University College Dublin
Propofol is commonly used for total
intravenous anaesthesia in human
medicine and offers a number of
potential benefits over inhaled agents
in veterinary practice. These include
smoother recovery and less
cardiovascular depression and there is
none of the operating room pollution
associated with gases. However,
propofol is not appropriate for use as
a single agent due to its poor analgesic
properties.
The authors examine the effects of
propofol used in combination with
fentanyl and atropine in dogs that
were premedicated with acepromazine
and carprofen. The mean time to
sternal recovery was 65 minutes and
the recovery was smooth and quiet.
Overall, the propofol and fentanyl
infusions provided stable
cardiovascular function and
satisfactory conditions for surgery,
although some modifications to the
infusion rates may be required to
reduce the long recovery times.
Veterinary Anaesthesia and Analgesia 36
(6): 523-531.
Factors associated with recovery
times in isoflurane-
anaesthetised horses
Debra Voulgaris and Erik
Hofmeister, University of Georgia
Recovery from general anaesthesia is
dangerous in horses with a range of
potentially fatal complications. The
risk of post-anaesthetic lameness is
known to correlate with the duration
of anaesthesia and so the authors
investigated the factors associated
with prolonged recovery in 381 horses
undergoing surgery.
Along with the duration of
anaesthesia, the other factors which
determined the time to standing were
hypothermia and intra-operative
hypotension. However, these factors
only explained a proportion of the
observed variability.
Veterinary Anaesthesia and Analgesia 36
(5): 414-420.
Effect of omeprazole on
oesophageal pH in
anaesthetised dogs
Ambra Panti and others, University
of Cambridge
Oesophageal stricture is a rare but
serious post-anaesthetic complication
which is believed to result from
oesophagitis due to gastro-
oesophageal reflux. The authors
investigate the effects of pre-operative
administration of the proton pump
inhibitor omeprazole in preventing
sudden reductions in oesophageal pH
caused by reflux. Among 47 dogs
undergoing elective surgery, there was
an 18% incidence of pH changes in
the treated group, compared with 52%
in the controls. So omeprazole is
effective in preventing reflux.
Journal of Small Animal Practice 50 (10):
540-544.
Cardiovascular effects of
dexmedetomidine and atropine
combinations in cats
Eduardo Monteiro and others,
University of Vila Velha, Brazil
Alpha-2 adrenoreceptor agonists are
widely used in clinical practice for
chemical restraint and analgesia for
minor procedures. However, they can
have adverse effects on cardiovascular
function which may only be partially
ameliorated by using them in
combination with anticholinergic
agents, such as atropine. The authors
assess these interactions in six cats.
They found that atropine
premedication prevented bradycardia
in dexmedetomidine-treated cats but
also induced hypertension and
increased myocardial oxygen
consumption.
Journal of Feline Medicine and Surgery 11
(10): 783-792.
Effects of fentanyl on minimum
alveolar concentration of
isoflurane in horses
Heather DiMaio Knych and others,
University of California, Davis
In addition to their analgesic effects,
opioid drugs can reduce the
concentration of inhaled agents
needed to achieve good anaesthesia.
The authors analyse the effects of
administering the opioid fentanyl at a
target concentration of 16ng/ml on
the minimum alveolar concentration
of isoflurane required for anaesthesia
in horses.
They found that fentanyl produced
no discernable isoflurane sparing
effects even at plasma concentrations
up to 32ng/ml and so routine use of
fentanyl as an anaesthetic adjuvant is
not recommended.
American Journal of Veterinary Research 70 (10): 1,193-1,200.
Evaluation of a novel aqueous
formulation of propofol in cats
Ralph Cleale and others, Fort
Dodge Animal Health, Princeton,
New Jersey
In its conventional formulation,
propofol is administered as an oil-in-
water macro-emulsion which has a
limited shelf life after the bottle is
broached. The authors describe studies to compare the
pharmacokinetic and
pharmacodynamic properties of a
new aqueous formulation with the
standard product. Their findings show
that there are no significant
differences between the two
formulations. However, the inclusion
of an antimicrobial preservative in the
novel product will minimise the
potential for bacterial contamination.
Journal of Veterinary Pharmacology and
Therapeutics 32 (5): 436-445.
Effects of remifentanil on
anaesthetic immobility and
analgesia in cats
Robert Brosnan and others,
University of California, Davis
An effective anaesthetic agent must
achieve a number of distinct
pharmacologic end points, including
centrally acting immobilisation,
analgesia and amnesia. The authors
examined the anaesthetic properties
of remifentanil at different
concentrations by assessing the
responses of treated cats to a thermal
threshold test. Their findings suggest
that immobility and analgesia were
independent anaesthetic end points in
these cats and so the results of
minimum alveolar concentration
evaluations should not be used to
infer analgesic potency.
American Journal of Veterinary Research 70 (9): 1,065-1,071.
Gas exchange in horses
mechanically ventilated with
oxygen or oxygen/helium
Francesco Staffieri and others,
University of Pennsylvania
General anaesthesia in horses affects
pulmonary gas exchange leading to
retention of carbon dioxide and
compromised oxygen uptake. Studies
in other species have demonstrated
that giving an oxygen rich mixture
can further impair gas exchange. The
authors gave either pure oxygen or an
oxygen/helium mixture to
anaesthetised horses maintained with
isoflurane. Their findings suggest that
lung function is better preserved in
patients ventilated with the oxygen
helium mixture than with pure
oxygen.
Equine Veterinary Journal 41 (8): 747-
752.
Assessment of ephedrine in
preventing anaesthesia-
induced hypotension
Christine Egger and others,
University of Georgia
Hypotension is a common problem
in patients receiving a general
anaesthetic. The authors investigate the effects of prior administration of
ephedrine on arterial blood pressure
in cats and dogs given standard
combinations of anaesthetic agents.
In cats given acepromazine,
butorphanol, ketamine and
isoflurane, systolic arterial pressure
was significantly below the baseline
level but remained above 80mmHg
until 25 minutes after induction of
anaesthesia. So prophylactic
ephedrine delayed but did not
prevent the onset of hypotension.
Canadian Veterinary Journal 50 (2): 179-
184.
Evaluation of Alfaxan-CD as an
intravenous anaesthetic in
young cats
Sanaa Zaki and others, University
of Sydney
Alfaxan-CD is a new formulation of
the water-insoluble, synthetic steroid
anaesthetic alfaxalone. The authors
evaluate this agent in inducing
anaesthesia in young cats, then
maintained with isoflurane. An iv
injection of Alfaxan-CD resulted in a
mean time to intubation of 122
seconds.
There was no evidence of
hypoxaemia in the 35 treated cats and
they had a rapid recovery from
anaesthesia. In some cats
premedicated with acepromazine and
butorphanol, the recovery scores
were better than those given no
premedication.
Australian Veterinary Journal 87 (3): 82-
87.
Seizures during medetomidine
sedation with local anaesthesia
in two dogs
Joanne Rainger and others,
University of Sydney
Two dogs which presented for
multiple skin biopsies were sedated
with intravenous medetomidine,
while lignocaine was given as a local
anaesthetic for the procedures. Both
dogs developed seizures, one during
the biopsy and again immediately
following reversal of medetomidine
with atipamezole, while the others
occurred two hours after the biopsies
were taken. The authors suspect a
drug interaction between the
medetomidine and lignocaine, which
may be related to the relatively large
dosages of the local anaesthetic.
Australian Veterinary Journal 87 (5):
188-192.
