Clinical Efficacy of Transdermal Fentanyl Pathches for Post-Operative Pain Mangement in Dogs
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Date
2018
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MAFSU, Nagpur
Abstract
In todays scenario dogs undergo a vast variety of surgeries following
which they experience considerable pain. Pain management is central to
veterinary practice. Routinely used post-operative pain management
regimens may prove to be either inadequate or stressful for the animals due
to frequent administration of injectables. Thus, a sustained release analgesic
using a transdermal delivery system was studied. The present study was
designed to evaluate the clinical efficacy of transdermal fentanyl patches for
managing post-operative pain following ovariohysterectomy in 12 dogs.
Group 1 (n=6) received a single transdermal fentanyl patch applied (on the
dorsal cervical region) 18h prior to surgery while Group 2 (n=6) receivedintramuscular injections of buprenorphine prior to surgery and repeated at
12h intervals for 3 days. Minimal alterations in clinico-physiological
parameters were observed. Mild reductions in rectal temperature (p<0.05)
and minor increases in heart (p<0.05) and respiratory rates (p<0.01) were
noted in dogs treated with transdermal fentanyl. All dogs exhibited
leukocytosis (p<0.05) and monocytosis from the beginning of the study. Mild
increase in PCV (p<0.05) was noted prior to surgery. Neutophilia without shift
to left (p<0.01) and lymphopenia (p<0.05) were observed 24h after surgery.
Serum creatinine values varied between intervals (p<0.05) in both groups
while mean values of BUN were significantly lower (p<0.01) in dogs receiving
transdermal fentanyl. ALT values differed non-significantly in both groups
whereas AST increased significantly (p<0.01) in the transdermal fentanyl
group. No adverse effects were observed in any of the dogs throughout the
study. Short Form of the Glasgow Composite Measure Pain Scale was used
to quantify the amount of pain experienced by each dog. Assessment of
spontaneous and evoked behaviours, interactions with these dogs and clinical
observations recorded at different time points of the study showed no
stiffness in gait or reluctance to move in any of the dogs. The dogs remained
behaviorally comfortable, quiet and ignored their surgical incision sites.
Maximum variation in pain exhibited by the dogs was observed on application
of gentle pressure 2 inches around the surgical wound. Snapping, growling,
guarding the surgical site, flinching, looking around and no reaction to
pressure applied were observed in the operated dogs. The maximum pain
score in the transdermal fentanyl patch group was 3 out of 24 whereas in the
buprenorphine group it was 4 out of 24. Extreme pain reactions like groaning,
screaming, licking or chewing of the wound, hunched or tense abdomen and
non-responsiveness to stimulation were not observed in any case indicating
adequate analgesia. Kruskal-Wallis H test was applied to analyze pain scores
between both groups. Mean ranks did not differ significantly for the groups,
however, slight fluctuations in pain were observed in the transdermal fentanyl
group. Pain scores of dogs in both groups reduced as the study progressed.
Rescue analgesia was not required to be administered at any time point in
either of the groups. The study demonstrates that the use of transdermal
fentanyl patches applied 18h prior to ovariohysterectomy provides postoperative
analgesia for 3 days which is non-inferior to repeated injections of
buprenorphine. It can be concluded that, transdermal fentanyl patches paired
with NSAID will provide reliable multimodal analgesia when used for
abdominal surgery in dogs, which is expected to produce substantial postoperative
pain if left untreated.
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