Page 60 - BSAVA Guide to Pain Management in Small Animal Practice

5 | Pharmacological treatment of pain

VetBooks.ir each drug, and this should be considered osteoarthritis the underlying in ammatory
process is always present, thus should be
when administering NSAIDs. Interestingly,
di erent formulations of the same active drug
suggests that continuous therapy with the
may have slightly di erent contraindications; continuously treated. Clinical evidence
therefore, it is essential to ensure the drugs are lowest e ective dose is more e ective than
used within the terms of their marketing pulse therapy. he minimal e ective dose can
authorization. be identi ed by tapering the administered dose
For all NSAIDs, a clinical response following once clinical improvement is apparent (Sparkes
oral administration is generally seen within 7 1 et al., 1 .
days of starting treatment. However, response Although many NSAIDs can be
to injectable NSAIDs is far quicker. If clinical administered prior to an anaesthetic according
improvement is apparent, the dose can be to their license, other restrictions of their use
reduced to a minimum e ective dose if must be considered when planning
speci ed on the datasheet , while if perioperative administration: hypotension,
improvement is not apparent, the treatment hypovolaemia, and dehydration are all absolute
should be discontinued. Transient contraindications to NSAI administration;
gastrointestinal side e ects are not uncommon hepatic and renal compromise may be absolute
immediately after starting the therapy and, or relative contraindications depending on the
while generally self-limiting, the treatment may drug considered. The clinical condition of the
need to be interrupted if they are severe or animal and the likelihood of adverse events
persistent. NSAIDs should not be used (hypotension, hypovolaemia) occurring in the
concomitantly with steroids, other NSAIDs or perioperative period should be considered
nephrotoxic medications. If a switch of NSAID is when choosing the timing of NSAID
deemed necessary, a 4 hour treatment free administration. Although many studies
period must be respected, with the notable demonstrated a pre emptive analgesic e ect of
exception of mavacoxib, which requires a various NSAIDs administered prior to surgery in
1 month treatment free period before dogs and cats, this was in most cases
administering any other NSAID. demonstrated using NSAIDs as the sole
hile response to NSAI s may be variable, analgesic during surgery (Lascelles et al., 1998;
especially when treating chronic pain, failure of a Horstman et al., 4; Bergmann et al., 7;
speci c NSAI to provide analgesia does not Bufalari et al., 1 ; im et al., 1 ; Nir et al.,
imply that all NSAI s will be ine ective. 16 . If other analgesic interventions are
Individual variability in disposition, local condi- incorporated in the anaesthetic protocol (e.g.
tions of the in ammatory site, and sensitivity to perioperative opioids, locoregional anaesthesia),
side e ects may partly explain variability in as it happens in a real life scenario, the di erent
response to NSAIDs. Most studies performed impact of pre- versus postoperative
comparing NSAI s demonstrated e ual e cacy administration is likely to be less relevant (Nir et
and not superiority. In terms of frequency of al., 16 . Pre emptive administration has been
gastrointestinal side e ects, NSAI s with greater linked to a post analgesic sparing e ect in
C selectivity are more likely to be tolerated. many prospective studies in humans and in a
hen switching NSAI , it is important to respect recent meta-analysis, and the safety of
the prescribed washout period. carprofen administered prior to anaesthesia has
A very common reason for NSAID failure in been demonstrated in normortensive and
chronic and persistent pain, for example hypotensive healthy dogs under experimental
osteoarthritis, is lack of owner compliance. The conditions (Boström et al., . n the other
owner may nd it di cult to resist the hand, renal function was temporarily impaired in
temptation to stop the therapy as soon as the healthy dogs that received carprofen prior to
clinical signs improve, resulting in their relapse. anaesthesia, if dehydration was induced by
In the setting of persistent pain such as administration of furosemide (Surdyk et al.,

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