Objective—To establish interval level measurement
in a prototype composite measure pain scale (CMPS)
for assessment of acute pain in dogs and to investigate
the scale's validity.
Animals—20 clinically normal dogs, 20 dogs with
medical conditions, and 117 dogs undergoing surgery.
Procedure—First, a scaling model was applied to the
CMPS descriptors to establish weights for each and
create a continuous scale. Subsequently, 5 observers
independently used the scale to score signs of pain in
4 groups of dogs (control dogs, dogs with medical
conditions, and 40 dogs undergoing soft tissue or
orthopedic surgery). Scores from each group and
from groups of conditions perceived to cause no,
mild, moderate, and severe pain were compared. In
addition, the scale was applied to 77 dogs undergoing
orthopedic or soft tissue surgery and scores were
compared with simultaneously derived numeric rating
scale (NRS) scores; comparisons were made
between surgical groups and with time after surgery.
Results—Calculated scale descriptor weights ranged
from –2.0 to 2.0 and were transformed to create a
continuous scale from 0 to 10. Median CMPS scores
differed significantly among the 4 study groups and
among pain severity groups and were typically greater
with increasing perceived pain severity. Agreement
was determined between CMPS and NRS scores, and
there was a significant and expected time effect and
difference between the CMPS scores of dogs undergoing
orthopedic and soft tissue surgery.
Conclusions and Clinical Relevance—Results indicate
that this interval level measurement scale is a
valid measure of acute pain in dogs. (Am J Vet Res