Validation of Orthopedic Postoperative Pain Assessment Methods for Dogs: A Prospective, Blinded, Randomized, Placebo-Controlled Study

Abstract

In the context of translational research, there is growing interest in studying surgical orthopedic pain management approaches that are common to humans and dogs. The validity of postoperative pain assessment methods is uncertain with regards to responsiveness and the potential interference of analgesia. The hypothesis was that video analysis (as a reference), electrodermal activity, and two subjective pain scales (VAS and 4A-VET) would detect different levels of pain intensity in dogs after a standardized trochleoplasty procedure. In this prospective, blinded, randomized study, postoperative pain was assessed in 25 healthy dogs during a 48-hour time frame (T). Pain was managed with placebo (Group 1, n = 10), preemptive and multimodal analgesia (Group 2, n = 5), or preemptive analgesia consisting in oral tramadol (Group 3, n = 10). Changes over time among groups were analyzed using generalized estimating equations. Multivariate regression tested the significance of relationships between pain scales and video analysis. Video analysis identified that one orthopedic behavior, namely ‘Walking with full weight bearing’ of the operated leg, decreased more in Group 1 at T24 (indicative of pain), whereas three behaviors indicative of sedation decreased in Group 2 at T24 (all p<0.004). Electrodermal activity was higher in Group 1 than in Groups 2 and 3 until T1 (p<0.0003). The VAS was not responsive. 4A-VET showed divergent results as its orthopedic component (4A-VETleg) detected lower pain in Group 2 until T12 (p<0.0009), but its interactive component (4A-VETbeh) was increased in Group 2 from T12 to T48 (p<0.001). Concurrent validity established that 4A-VETleg scores the painful orthopedic condition accurately and that pain assessment through 4A-VETbeh and VAS was severely biased by the sedative side-effect of the analgesics. Finally, the video analysis offered a concise template for assessment in dogs with acute orthopedic pain. However, subjective pain quantification methods and electrodermal activity need further investigation.

Correlação entre as escalas analógica visual, de Glasgow, Colorado e Melbourne na avaliação de dor pós-operatória em cadelas submetidas à mastectomia total unilateral

“…Muitas vezes, apresentavam-se lentos ou relutantes ou até mesmo recusavam-se a movimentar, pontuando apenas nesse quesito quatro pontos. Apesar de esse subitem ser sensível para a avaliação álgica, ele sofre influência direta da sedação, ficando difícil diferenciar a ausência de movimento por causa de dor ou por sua associação à intensa sedação pós-operatória (Rialland et al, 2011). Os maiores escores observados pela movimentação acompanharam o somatório total de pontos pela GCMPS entre uma e seis horas de pós-operatório, com uma pontuação média total que variou entre seis e 7,5 pontos.…”

“…A EVA é representada por uma linha horizontal de zero a 100mm, indicando da ausência de dor até a máxima dor possível, onde o avaliador demarca um ponto e posteriormente, com o auxílio de uma régua milimétrica, observa a pontuação atribuída ao animal (Hellyer et al, 2007;Rialland et al, 2011).…”

Comparison of medetomidine—morphine and medetomidine—methadone for sedation, isoflurane requirement and postoperative analgesia in dogs undergoing laparoscopy

“…Pain is a less likely cause as there was no reason for the animals to be in pain before anaesthesia, PR remained within usual limits and the pain scores were low postoperatively. The 4AVet scoring system has been shown to have acceptable reliability (Rialland et al 2012).…”

Analgesic comparison of systemic lidocaine, morphine or lidocaine plus morphine infusion in dogs undergoing fracture repair

“…In the current study, the majority of dogs reported the use of various scales (e.g., visual analog, numerical rating, simple descriptive and composite) developed and correlated specifically for dogs 1,23,40,41 . In the current study, two methods (i.e., the GCPS and VAS), were used to obtain a more accurate overall impression of pain.…”

“…The VAS system is a simple way of scoring pain and is commonly used for both humans and animals. The GCPS system is internationally recognized and has been reported to be as reliable and reproducible for pain assessment in dogs as the VAS system 40 . In addition, only one observer scored all dogs to avoid interobserver variability in the subjective evaluation.…”