Measurement of chronic pain in companion animals: Priorities for future research and development based on discussions from the Pain in Animals Workshop (PAW) 2017

The intravenous administration of blood cell secretome can improve clinical signs in dogs with osteoarthritis

We aimed to evaluate the effect of the intravenous (IV) administration of blood cell secretome (BCS) compared to its intra-articular (IA) administration. In this cross-over study, ten dogs with bilateral hip osteoarthritis were initially assigned to an IA group (IAG). After a 180-day follow-up, the same 10 animals were assigned to an IV group (IVG). IAG received a single IA administration of 3 ml of BCS per hip joint, and IVG received a single 6 ml IV administration of BCS. Following each treatment, follow-up was conducted on days 0, 8, 15, 30, 60, 90, 120, 150, and 180. In each follow-up, copies of the Canine Brief Pain Inventory (divided into pain interference score - PIS and Pain Severity Score - PSS), Liverpool Osteoarthritis in Dogs (LOAD), and Canine Orthopedic Index (COI, divided into function, gait, stiffness, and quality of life) were obtained. Results were analyzed with the Mann-Whitney test, and Kaplan-Meier estimators were calculated and compared, p < 0.05. The animals had a mean age of 7.6 ± 2.9 years and bodyweight of 27.8 ± 3.6 kg. Seven hips were classified as moderate osteoarthritis, and three as severe. No differences were found between groups from days 0 to +60d, with both groups showing clinically significant improvements. Improvements in the IAG lasted up to +120d. Kaplan-Meier estimators showed that dogs in IAG took longer to record the considered events. IVG also showed positive clinically significant results with different instruments. IV administration of BCS can improve the overall condition of dogs with hip OA, but the IA administration produces longer-lasting results.

Translation and linguistic validation into Spanish of the Owner-Reported Outcome Measure "Liverpool Osteoarthritis in Dogs"

Introduction

Assessing chronic pain in dogs has been greatly favoured by the development of Owner-Reported Outcome Measures. Among them, the Liverpool Osteoarthritis in Dogs (LOAD) has been widely used for this purpose. Most of these tools have been written in English and its use by non English natives requires not only translation but also linguistic validation for use by veterinarians and owners. For its use, the LOAD has not undergone translation into Spanish and the objective was to generate a linguistically validated Spanish translation of the LOAD.

Methods

Following the World Health Organisation and the International Society for Pharmacoeconomics and Outcomes Research published guidelines, the original LOAD English version underwent analysis and translation by two native linguists proficient in the target language. Both translations were then reviewed by a third native linguist to identify potential disparities and establish a cohesive translation (reconciliation). Subsequently, an independent linguist, fluent in both English and the target language, conducted the back translation. Finally, the research team compared the original and back translated versions to pinpoint and resolve any significant differences. Following the creation of the translated version, a cognitive debriefing was conducted to assess the questionnaire within the target population.

Results

A total of 89 surveys were distributed to dog owners of varying ages, genders, and socioeconomic backgrounds. Although there were some suggestions and comments, and some adjustments were made, all respondents found the survey to be clear, achieving a linguistic validation of the Spanish LOAD.

Translation to Spanish and linguistic validation of the Canine Brief Pain Inventory

Introduction

Pain scales for the assessment of chronic pain have been developed for dogs but they should be translated and linguistically validated to be used by owners with different native languages. The Canine Brief Pain Inventory (CBPI) is widely employed for this purpose but has not been translated into Spanish. Thus, the aim was to produce a validated translation of the Spanish CBPI.

Methods

The original English version of the CBPI was analyzed and translated by two native linguists of the target language and both revised by a third native linguist to identify potential discrepancies and create a unified translation (reconciliation). Then, an independent linguist with native fluency in English and the target language drafted the back-translation. Finally, the research team confronted both the original and the back-translation to identify and solve relevant differences. Once the translated version was produced, a cognitive debriefing was performed to assess the questionnaire in the target population.

Results

A total of 50 surveys were conducted to dog and cat owners of different ages, sex, and socio-economic characteristics. All respondents considered the survey to be clear and a final version of the Spanish CBPI has been produced.

Nine-axis inertial measurement unit output discriminates activities of varying intensity in the dog

OBJECTIVE

To explore relationships between 9-axis inertial measurement unit (IMU) output and activities of varying intensity in dogs of various sizes.

ANIMALS

20 healthy, agility course-trained dogs of various ages and sizes.

PROCEDURES

Height, weight, body condition score, age, length from IMU to the ischium, and height of IMU to the floor were recorded. Dogs performed a series of activities (rest, walk, trot, and agility course) while wearing the IMU device. IMU and video output were reviewed by independent investigators. Correlations and multiple regression models were used to explore relationships between independent variables and IMU output.

RESULTS

Calibration demonstrated excellent correlation and concordance between IMUs (intraclass correlation > 0.9) and that the IMUs reliably measured a known acceleration (gravity at rest). Resultant vector magnitude {sqrt[(x^2) + (y^2) + (z^2)]} normalized to body size was calculated from the data. IMU output clearly discriminates between activities of varying intensity in the dog.

CLINICAL RELEVANCE

The inability to accurately measure chronic pain is a barrier to the development of new, or critical evaluation of, therapeutics. Activity monitors (AM) may be the ideal diagnostic target since they are small and provide objective data that can be collected while the pet remains in its natural environment. These results demonstrate the concurrent and predictive validity of the IMU tested. Our long-range goal is to validate an open-source algorithm for the IMU so activity in a pet's natural environment can be used as an outcome measure in future studies.

The beneficial role of companion animals in translational pain research

The use of spontaneous painful disease in companion pet animals has been highlighted as one of the changes that could be made to help improve translation of basic science to new therapeutics, acting as a bridge between preclinical and clinical studies, with the goal of accelerating the approval of new therapeutics. This review focuses on the utility of companion pet dogs for translational research by reviewing what outcome measures can be measured, and importantly, the relevance of these outcome measures to human translational research. It also details the practical considerations involved in incorporating companion dogs into human therapeutic development.

Determination of the center of mass in a heterogeneous population of dogs

The center of mass (CoM) is the location in a body where mass distribution is balanced. It has a fundamental role in balance and motion which has been poorly described in the dog. The objective of this study was to estimate the variance of the center of mass (CoM) in a heterogeneous population of client-owned dogs and to describe the relationship between CoM, subject morphometrics and an inertial measurement unit (IMU) box positioned ventrally on a neck collar. A single force platform and a reaction board were used to determine CoM in the transverse, sagittal and dorsal planes in thirty-one healthy adult dogs. A series of morphometric measurements were acquired with each dog standing, including distances relative to an IMU box positioned ventrally on a neck collar. Mean transverse plane CoM was 48% the distance from ischium to the IMU box, near the xiphoid process. Mean sagittal place CoM was 59% the width of the chest on the left side. Mean dorsal plane CoM was 41% the distance from the most dorsal to the most ventral aspect of the body. Dog length was the primary variable required to maximize the relationship between three-dimensional CoM and identifiable variables measured. A CoM based normalization procedure should be considered to normalize mass or motion based outcome measure output (e.g., ground reaction forces, vector acceleration) in a heterogeneous population of dogs. Future research will be needed to determine if CoM-based normalization procedures reduce variance in outcome measures affected by subject morphometrics.

Best practices for measuring and reporting ground reaction forces in dogs

Kinetic gait analysis and ground reaction forces (GRFs) have been used in hundreds of scientific manuscripts. Specific methodology, interpretation of results, and translation to clinical veterinary medicine have been inconsistent. This impedes the advance of veterinary medicine and poses a risk to patients. The objective of this report was to address methodological variations and share our consensus on a recommended approach with viable alternatives to data collection methods, analysis, reporting, and interpretation for GRFs in the dog. Investigators with experience performing kinetic gait analysis reviewed the literature and discussed the topics that most influenced GRF data collection, reporting, and interpretation. Methodological variations were reported and a consensus from the group was devised. There are several reasonable alternatives to collect, report, and interpret GRFs in dogs appropriately. Attention to detail is required in several areas to collect and report them. This review and consensus report should assist future investigations and interpretations of studies, optimize comparison between publications, minimize use of animals, and limit the investment in cost and time.

Chronic Pain in Dogs and Cats: Is There Place for Dietary Intervention with Micro-Palmitoylethanolamide?

The management of chronic pain is an integral challenge of small animal veterinary practitioners. Multiple pharmacological agents are usually employed to treat maladaptive pain including opiates, non-steroidal anti-inflammatory drugs, anticonvulsants, antidepressants, and others. In order to limit adverse effects and tolerance development, they are often combined with non-pharmacologic measures such as acupuncture and dietary interventions. Accumulating evidence suggests that non-neuronal cells such as mast cells and microglia play active roles in the pathogenesis of maladaptive pain. Accordingly, these cells are currently viewed as potential new targets for managing chronic pain. Palmitoylethanolamide is an endocannabinoid-like compound found in several food sources and considered a body's own analgesic. The receptor-dependent control of non-neuronal cells mediates the pain-relieving effect of palmitoylethanolamide. Accumulating evidence shows the anti-hyperalgesic effect of supplemented palmitoylethanolamide, especially in the micronized and co-micronized formulations (i.e., micro-palmitoylethanolamide), which allow for higher bioavailability. In the present paper, the role of non-neuronal cells in pain signaling is discussed and a large number of studies on the effect of palmitoylethanolamide in inflammatory and neuropathic chronic pain are reviewed. Overall, available evidence suggests that there is place for micro-palmitoylethanolamide in the dietary management of chronic pain in dogs and cats.

Serum artemin is not correlated with sensitivity within dogs with naturally occurring osteoarthritis pain

Osteoarthritis (OA) pain is associated with peripheral and central sensitization in humans and results in widespread increased sensitivity across the body. Sensitization contributes to the OA-associated pain (OAP) state. We recently identified increased levels of an endogenous neurotrophic factor, artemin (ARTN), in dogs with OAP compared to healthy pain-free controls. Circulating ARTN released from damaged tissues in OA, may play a central role in widespread sensitivity and pain. However, the relationship between ARTN and somatosensory sensitivity remains unknown. The study aimed to assess the relationship between serum ARTN concentrations and measures of sensitivity in dogs with OAP using quantitative sensory testing. We hypothesized that there would be a positive association between circulating ARTN and increased sensitivity to mechanical and thermal stimuli in dogs with OAP. We used linear and logistic regression models to assess the relationship between ARTN, sensitization, and pain within a cohort of 43 dogs with spontaneous OAP. Serum ARTN was not associated with the degree of sensitization within dogs with OAP. Further, across dogs with varying OAP severity, we did not find any association between ARTN, and clinical measures of joint pain and disability. Although a relationship between ARTN and joint pain was not ruled out.