A look through the recent international literature on managing pain - Veterinary Practice
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A look through the recent international literature on managing pain

Efficacy and safety of
meloxicam administered as
a transmucosal oral spray

Elizabeth Cozzi and Michael
Spensley, Abbot Laboratories,
Abbott Park, Illinois

Oral transmucosal delivery of drugs
has a number of potential advantages
over conventional oral formulations
in terms of ease of administration,
rapid absorption through the mucous
membranes and elimination of the
first pass effect (in which part of the
dose is lost during passage through
the intestinal wall and liver).

The authors examined the
potential value of a novel
transmucosal formulation of the
non-steroidal anti-inflammatory drug
meloxicam, developed as the first
veterinary drug for administration by
this route. The drug was
administered to 280 client-owned
dogs with osteoarthritis in a multi-
centre, randomised placebo-
controlled trial in which the patients
were treated once daily for 28 days.

Client pain scores were
significantly lower at 14 and 28 days
for the treated group although
veterinary assessments of pain on
palpation were no different between
groups. There was some evidence of
gastrointestinal adverse effects but
the transmucosal formulation of
meloxicam appears to be a safe and
effective method for controlling pain
in dogs with osteoarthritis.

Journal of Veterinary Pharmacology
36 (6): 609-616.

Absorbable gelatin sponges
for pain control following
eye enucleation in dogs

Christina Ploog and others,
University of Illinois

Although removal of the globe
following disease or trauma is a
common surgical procedure in
veterinary practice, maintaining good
post-operative analgesia remains a

The authors compared the quality
of pain control achieved with
absorbable gelatin haemostatic
sponges in comparison with
retrobulbar injections of the same
local anaesthetic agents in dogs
following this procedure.

While there were differences over
time in heart rate, response to touch,
total pain scores, etc., there were no
significant overall differences
between the two groups. Thus, the
impregnated gelatin sponges were a
satisfactory method for achieving local anaesthesia.

Journal of the American Veterinary
Medical Association
244 (1): 57-62.

Cardiovascular and
respiratory effects of
intramuscular alfaxalone in

Tamara Grubb and others,
Washington State University

Anaesthetic induction using
intravenous agents in fractious cats
can be extremely challenging and
while reliance on inhaled agents for
both induction and maintenance is
feasible, it does create increased
mortality risks.

The authors
investigated the potential use of
alfaxalone as an intramuscular
induction agent. A total of 12
healthy adult cats were sedated with
either dexmedetomidine or
before receiving 5mg/kg bodyweight
of alfaxalone. Satisfactory
anaesthesia was achieved in both
groups but recovery was prolonged
with excitement, ataxia and hyper-
reactivity, so this formulation is not
recommended for surgery in cats.

Journal of Feline Medicine and Surgery 15
(10): 858-865.

Effect of fluconazole on
anaesthetic recovery times
in horses undergoing ocular

Stephanie Krein and others, Tufts
University, North Grafton,

General anaesthesia is often required
when carrying out ocular surgery in
horses as sedation and local
anaesthesia may be inadequate for
such delicate procedures. The authors
examined the clinical records for 81
horses undergoing ocular procedures
in search of factors that might be
associated with the potential hazards
of prolonged recovery times.

found that those horses that had
received treatment with the
antifungal fluconazole before
induction with ketamine and
midazolam were more likely to
experience a prolonged anaesthetic
recovery. Duration of anaesthesia
and premedication with
acepromazine were also identified as
risk factors for prolonged recovery

Journal of the American Veterinary
Medical Association
244 (5): 577-581.

Low-dose medetomidine
infusion for healthy dogs

Eva Rioja and others, University
of Guelph, Ontario, Canada

Balanced anaesthesia involving the
co-administration of multiple agents
offers the potential advantage of requiring a smaller total dose and
minimising the risks of adverse
effects. The authors investigated the
value of providing a low dose
infusion of medetomidine as a
1mg/kg bolus and at a constant rate
of 1mg/kg per hour in dogs
maintained on isoflurane anaesthesia
for routine ovariohysterectomy.

found that this combination provided
acceptable and stable cardiovascular
performance with lower isoflurane
concentrations and a smooth
anaesthetic recovery.

Canadian Veterinary Journal 54 (9):

Long term pharmacokinetics
of meloxicam in rabbits

Katie Delk and others, Kansas
State University

Few analgesic drugs have been
approved for long-term use in
veterinary patients. In rabbits
requiring pain medication, meloxicam
is a popular choice for off-label use
as it is available in a palatable oral
formulation, is not a controlled
substance and is known to be well
tolerated in many mammalian

The authors investigated the
pharmacokinetics of this agent when
administered at a daily oral dose of
1mg/kg bodyweight for 29 days.
Plasma concentrations were similar to those reported in rabbits treated
for up to five days, indicating that the
dose would be safe for long-term
treatment in this species.

American Journal of Veterinary Research
75 (2): 195-199.

Intramuscular injections of
dexmedetomidine and
hydromorphone for sedating

Jennifer Carter and others, Ross
University, St Kitts, West Indies

Intravenous administration of pre-
anaesthetic and anaesthetic drugs
may be impractical in some canine
patients because of temperament,
small vein diameter, etc. The authors
compared the onset time and quality
of sedation achieved with
intramuscular injections of
dexmedetomidine and
hydromorphone into different muscle

Resting pulse and respiratory
rates were not significantly different
in dogs sedated with IM injections
into the semimembranosus, cervical,
gluteal or lumbar muscle groups.
However, semimembranosus muscle
inoculations resulted in significantly
higher sedation scores and there was
a shorter time to onset of sedation.

Journal of the American Veterinary
Medical Association
243 (11): 1,569-

Sedation of hyperthyroid cats
with subcutaneous alfaxalone
and butorphanol

Sue Ramoo and others, Advanced VetCare, Kensington, Victoria

Cats with increased circulating thyroid
hormone can be difficult to handle and
while a number of sedation strategies
have been used in such patients, full
details of the physiological effects are
usually lacking.

The authors assessed
the cardiovascular, respiratory and
sedative effects of a combination of
3mg/kg alfaxalone and 0.2mg/kg
butorphanol administered
subcutaneously in 20 client-owned
hyperthyroid cats. The maximum
sedation score was recorded 45
minutes after treatment and the
combination was deemed to provide
satisfactory sedation in cats undergoing
short duration procedures.

Australian Veterinary Journal 91 (4): 131-

Pharmacokinetics of
intravenous midazolam in

John Hubbell and others, Ohio State University

Midazolam is a water-soluble
benzodiazepine used to control
seizures and to enhance muscle
relaxation in horses but there are no
published data describing the
pharmacokinetics of the agent in this

The authors administered
midazolam intravenously at 0.05 and
0.1mg/kg doses in six healthy horses.
Their findings showed that the mean terminal half-life was 216 minutes and
408 minutes at the lower and higher
dose, respectively. Cardiorespiratory
parameters and sedation scores were
unchanged but several horses showed
evidence of agitation, postural sway
and weakness while one given the
higher dose became recumbent.

Equine Veterinary Journal 45 (6): 721-725.

Effects of intravenous
lidocaine on isoflurane
anaesthesia in rabbits

Rodney Schnellbacher and others, Kansas State University

The local anaesthetic lidocaine is used
in human and veterinary medicine to
reduce the concentration of inhalant
anaesthetic needed for surgery and
reduce the risks of haemodynamic

The authors investigated
the effects of a continuous rate
infusion of 50 or 100ug/kg/minute
lidocaine (following a loading dose of
2mg/kg) on the minimum alveolar
concentration of isoflurane required to
maintain adequate anaesthesia in five
12-month-old New Zealand white
rabbits. At both doses, the co-
administration of lidocaine significantly
reduced the MAC of isoflurane needed
to eliminate any response to the
application of a tail clamp.

American Journal of Veterinary Research 74
(11): 1,377-1,384.

Future approaches to the
treatment of neuropathic
pain in dogs

Sandra Sanchis-Mora and others, Royal Veterinary College, London

Neuropathic pain is considered to be
one of the most painful and challenging chronic pain conditions in
human medicine and is even more
difficult to recognise and treat in
veterinary patients. The authors review
knowledge on the assessment and
treatment of these disorders in dogs
and examine the potential options for
future treatment.

They conclude that a
multimodal strategy involving a
combination of agents such as non-
steroidal anti-inflammatories,
anticonvulsants such as a gabapentin,
opioids including tramadol and
methadone, and tricyclic
antidepressants such as amitriptyline
may help improve quality of life in
affected animals.

Companion Animal 19 (1): 8-13.

Propofol or
anaesthesia for evaluating
laryngeal function in dogs

Kelci McKeiman and others, Oklahoma State University

Laryngeal paralysis is a common
acquired condition in older, large breed
dogs. Thiopental has been the favoured
anaesthetic agent for investigations of
laryngeal function in this species but
that compound is no longer
commercially available.

The authors
compare the use of propofol and
propofol/ketamine as local anaesthetics
in healthy dogs undergoing
laryngoscopy. They found that
ketamine did not allow for a reduction
in the propofol dose and caused
increased respiratory depression,
making it a poor addition to propofol
for investigations of laryngeal function.

Journal of the American Animal Hospital
50 (1): 19-26.

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