RELATIONSHIP BETWEEN PHYSIOLOGICAL FACTORS AND CLINICAL PAIN IN DOGS SCORED USING A NUMERICAL RATING-SCALE

A study was designed to investigate the association between heart rate , respiratory rate and pupil dilation and a subjective pain score allo cated using a numerical rating scale (NRS), Four groups of dogs (n = 1 7 to 20 per group) were included: orthopaedic surgery cases, soft tiss ue surgery cases, dogs with medical conditions and healthy dogs, Each dog was examined by five veterinary surgeons within a four-hour period , When examining each dog, the observers recorded heart rate, respirat ory rate, pupil dilation (present or absent) and a pain score using a NRS (range 0 to 10), For surgical cases, all study assessments were ca rried out between 21 and 27 hours following the end of surgery, The co rrelation coefficients between physiological parameters and NRS score were small but, depending on the analysis, were significant for heart rate and NRS score (P < 0.05). However, the size of the coefficient, 0 -168, indicated that the relationship was not biologically significant , There was no association between respiratory rate and NRS score, Ana lysis of the relationship between NRS score and pupil dilation indicat ed that there was an association between this factor and pain, dependi ng on the analysis. This was significant for the surgical groups (P < 0.05) but not for the other groups, These findings indicate that heart rate and respiratory rate are not useful indicators of pain in hospit alised dogs, It is also unlikely that pupil dilation will be a useful tool in the assessment of pain.