Spontaneous painful disease in companion animals can facilitate the development of chronic pain therapies for humans

Development and Validation of a Canine Health-Related Quality of Life Questionnaire and a Human-Canine Bond Questionnaire for Use in Veterinary Practice

The use of valid questionnaires to assess dogs' health-related quality of life (HRQoL) in veterinary practice can improve canine health outcomes and communications between veterinarians and caretakers of dogs. The Canine HRQoL Questionnaire (Canine HRQoL-Q) and the Human-Canine Bond Questionnaire (HCBQ) were developed and validated to fulfill this need. A literature review, interviews with veterinarians, and focus groups with caretakers were conducted to generate questionnaire items and develop draft questionnaires, which were piloted with caretakers to establish their content validity. Measurement properties were evaluated using data from a prospective survey study (N = 327). Draft Canine HRQoL-Q and HCBQ measures were developed, including a domain structure, items, recall period, and scale/response options. Refinements were made via iterative cognitive interviews with caretakers. When no additional revisions were indicated and content validity was established, the questionnaires were psychometrically tested. Ceiling effects were observed for all items, and factor analyses indicated that the pre-specified domains are appropriate. Internal consistency was demonstrated for the HCBQ (α = 0.79-0.86) and all but the social functioning domain of the Canine HRQoL-Q (α = 0.60). Test-retest reliability for the Canine HRQoL-Q was generally moderate-to-good (with intraclass correlation coefficients (ICCs) > 0.79). Test-retest reliability for the HCBQ was moderate (ICCs: 0.70-0.79) except for the trust domain (ICC: 0.58). Known-groups validity was demonstrated via significant differences (p < 0.05) in scores for health/bonding groups. Convergent validity was supported (r > 0.40) between all domains and the total scores for both questionnaires. The Canine HRQoL-Q and the HCBQ are valid, reliable measures of canine HRQoL for use in veterinary clinics and appear to measure related but distinct concepts that contribute to canine health and wellness.

Pilot comparison of outcome measures across chemical and surgical experimental models of chronic osteoarthritis in the rat (Rattus norvegicus)

Relatively little work has evaluated both the disease of osteoarthritis (OA) and clinically-relevant pain outcome measures across different OA models in rats. The objective of this study was to compare sensitivity, pain, and histological disease severity across chemical and surgical models of OA in the rat. Stifle OA was induced in Sprague-Dawley rats via intraarticular injection of monoiodoacetate (MIA) or surgical transection of anterior cruciate ligament and/or destabilization of medial meniscus (ACL+DMM or DMM alone). Reflexive (e.g., mechanical and thermal stimuli) measures of sensitivity and non-reflexive assays (e.g., lameness, static hindlimb weight-bearing asymmetry, dynamic gait analysis) of pain were measured over time. Joint degeneration was assessed histologically. Six-weeks post OA-induction, the ACL+DMM animals had significantly greater visually observed lameness than MIA animals; however, both ACL+DMM and MIA animals showed equal pain as measured by limb use during ambulation and standing. The MIA animals showed increased thermal, but not mechanical, sensitivity compared to ACL+DMM animals. Joint degeneration was significantly more severe in the MIA model at 6 weeks. Our pilot data suggest both the ACL+DMM and MIA models are equal in terms of clinically relevant pain behaviors, but the MIA model is associated with more severe histological changes over time potentially making it more suitable for screening disease modifying agents. Future work should further characterize each model in terms of complex pain behaviors and biochemical, molecular, and imaging analysis of the sensory system and joint tissues, which will allow for more informed decisions associated with model selection and investigative outcomes.

The history of pain measurement in humans and animals

Pain needs to be measured in order to be studied and managed. Pain measurement strategies in both humans and non-human animals have varied widely over the years and continue to evolve. This review describes the historical development of human and animal algesiometry.

The influence of IL-1 and C-reactive protein levels in synovial fluid of companion dogs with bilateral hip osteoarthritis on various clinical disease parameters

OBJECTIVE

To evaluate IL-1 and C-reactive protein (CRP) levels in the synovial fluid in dogs with bilateral hip osteoarthritis and their relation to animals' clinical, radiographic, and thermographic disease signs.

SAMPLE

100 joints from police working dogs.

PROCEDURES

Synovial fluid, IL-1, and CRP levels, weight distribution, joint range of motion, thigh girth, digital thermography, and radiographic signs of the joints were recorded. Data from 4 clinical metrology instruments (CMIs) were collected. Results were compared by age, sex, and Orthopedic Foundation for Animals hip scores with the independent samples t test, ANOVA, and Pearson correlation coefficient (P < .05).

RESULTS

The sample included 100 pelvic limbs, equally distributed between left and right pelvic limbs 30 males and 20 females, with a mean age of 6.5 ± 2.4 years and body weight of 26.7 ± 5.2 kg. IL-1 levels, particularly above 200 pg/mL, may be related to the development of caudolateral curvilinear osteophyte, which then expresses a toll on the patient's levels of pain and activity. It was unclear if the CRP levels were a consequence of inflammatory activity within the joint or a reflection of a better prognosis. Increasing body weight was related to worse CMI scores.

CLINICAL RELEVANCE

We described the relation of IL-1 and CRP synovial concentration levels with several clinical signs, diagnostic imaging, laboratory findings, and CMI results of animals with osteoarthritis. Further studies are required to determine the interest of each parameter for the prognosis and treatment monitoring.

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.

Innovations and advances in modelling and measuring pain in animals

Best practices in preclinical algesiometry (pain behaviour testing) have shifted over the past decade as a result of technological advancements, the continued dearth of translational progress and the emphasis that funding institutions and journals have placed on rigour and reproducibility. Here we describe the changing trends in research methods by analysing the methods reported in preclinical pain publications from the past 40 years, with a focus on the last 5 years. We also discuss how the status quo may be hampering translational success. This discussion is centred on four fundamental decisions that apply to every pain behaviour experiment: choice of subject (model organism), choice of assay (pain-inducing injury), laboratory environment and choice of outcome measures. Finally, we discuss how human tissues, which are increasingly accessible, can be used to validate the translatability of targets and mechanisms identified in animal pain models.

Measurement properties of grimace scales for pain assessment in non-human mammals: a systematic review

ABSTRACT

Facial expressions of pain have been identified in several animal species. The aim of this systematic review was to provide evidence on the measurement properties of grimace scales for pain assessment. The protocol was registered (SyRF#21-Nov-2019) and the study is reported according to the PRISMA guidelines. Studies reporting the development, validation, and the assessment of measurement properties of grimace scales were included. Data extraction and assessment were performed by two investigators, following the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines. Six categories of measurement properties were assessed: internal consistency, reliability, measurement error, criterion and construct validity, and responsiveness. Overall strength of evidence (high, moderate, low) of each instrument was based on methodological quality, number of studies and studies' findings. Twelve scales for nine species were included (mice, rats, rabbits, horses, piglets, sheep/lamb, ferrets, cats and donkeys). Considerable variability regarding their development and measurement properties was observed. The Mouse, Rat, Horse and Feline Grimace Scales exhibited high level of evidence. The Rabbit, Lamb, Piglet and Ferret Grimace Scales and Sheep Pain Facial Expression Scale exhibited moderate level of evidence. The Sheep Grimace Scale, EQUUS-FAP and EQUUS-Donkey-FAP exhibited low level of evidence for measurement properties. Construct validity was the most reported measurement property. Reliability and other forms of validity have been understudied. This systematic review identified gaps in knowledge on the measurement properties of grimace scales. Further studies should focus on improving psychometric testing, instrument refinement and the use of grimace scales for pain assessment in non-human mammals.

Pain Treatment in the Companion Canine Model to Validate Rodent Results and Incentivize the Transition to Human Clinical Trials

One of the biggest challenges for analgesic drug development is how to decide if a potential analgesic candidate will work in humans. What preclinical data are the most convincing, incentivizing and most predictive of success? Such a predicament is not unique to analgesics, and the pain field has certain advantages over drug development efforts in areas like neuropsychiatry where the etiological origins are either unknown or difficult to ascertain. For pain, the origin of the problem frequently is known, and the causative peripheral tissue insult might be observable. The main conundrum centers around evaluation of translational cell- and rodent-based results. While cell and rodent models are undeniably important first steps for screening, probing mechanism of action, and understanding factors of adsorption, distribution metabolism and excretion, two questions arise from such studies. First, are they reliable indicators of analgesic performance of a candidate drug in human acute and chronic pain? Second, what additional model systems might be capable of increasing translational confidence? We address this second question by assessing, primarily, the companion canine model, which can provide particularly strong predictive information for candidate analgesic agents in humans. This statement is mainly derived from our studies with resiniferatoxin (RTX) a potent TRPV1 agonist but also from protein therapeutics using a conjugate of Substance P and saporin. Our experience, to date, is that rodent models might be very well suited for acute pain translation, but companion canine models, and other large animal studies, can augment initial discovery research using rodent models for neuropathic or chronic pain. The larger animal models also provide strong translational predictive capacity for analgesic performance in humans, better predict dosing parameters for human trials and provide insight into behavior changes (bladder, bowel, mood, etc.) that are not readily assessed in laboratory animals. They are, however, not without problems that can be encountered with any experimental drug treatment or clinical trial. It also is important to recognize that pain treatment is a major veterinary concern and is an intrinsically worthwhile endeavor for animals as well as humans.

Effect of a single intra-articular high molecular weight hyaluronan in a naturally occurring canine osteoarthritis model: a randomized controlled trial

BACKGROUND

Osteoarthritis (OA) is a complex joint disease and chronic pain source, affecting a patient's quality of life and posing a financial burden. As the dog is considered a nearly ideal species for translation research of human OA and the most used model for research, exploring spontaneous dog OA under the One Health/One Medicine concept can improve both humans and dogs' health and well-being.

METHODS

In a clinical treatment experiment, forty (N=40) joints were selected and randomly assigned to a control group (CG), which received 0.9% NaCl or a treatment (HG), which received Hylan G-F 20. Evaluations were performed on treatment day (T0), 8, 15, 30, 90, and 180 days post-treatment. They consisted of four different Clinical Metrology Instruments (CMI), evaluation of weight distribution, joint range of motion, thigh girth, radiographic and digital thermography imaging, synovial fluid interleukin-1 (IL-1), and C-reactive protein concentrations. Results were compared with repeated measures ANOVA, with a Huynh-Feldt correction, Paired samples T-test, or Wilcoxon signed-ranks test, with p<0.05.

RESULTS

Patients had a mean age of 6.5±2.4 years and a bodyweight of 26.6±5.2kg, and joints graded as mild (n=28, 70%), moderate (n=6, 15%), and severe OA (n=6, 15%). No differences were found between groups at T0. Symmetry index and deviation showed significant improvements in HG from 30 days (p<0.01) up to 180 days (p=0.01). Several CMI scores, particularly pain scores, improved from 90 to 180 days. Radiographic signs progressed in both groups. In both groups, increasing body weight and age corresponded to worse clinical presentation. IA hyaluronan administration produced increased lameness in six cases, which resolved spontaneously.

CONCLUSIONS

This study characterizes the response to treatment with Hylan G-F 20, which can produce significant functional and pain level improvements in patients with OA, even those with factors related to worse response to treatment.

Evaluation of digital thermography imaging to assess and monitor treatment of police working dogs with naturally occurring hip osteoarthritis

BACKGROUND

In dogs, thermal imaging has been documented only recently, but a growing interest in this modality has led to studies using thermography to assess pathologies in the canine hip, stifle, elbow, intervertebral disc, and bone neoplasia. This study aimed to evaluate the use of digital thermography in assessing and evaluating treatment response in dogs with hip osteoarthritis (OA) and comparing its results with an objective measure and two clinical metrology instruments. In an experimental, randomized, double-blinded study, one hundred hip joints of fifty police working dogs with bilateral hip OA were evaluated. A dorsoventral and lateral thermographic image were obtained on days 0, 8, 15, 30, 90, and 180. Mean and maximal temperatures were determined. Additionally, the animal's weight-bearing distribution and radiographic examination of the hip joint (extended legs ventrodorsal view) were performed. Copies of the Canine Brief Pain Inventory (CBPI) and Canine Orthopaedic Index (COI) were obtained. Results were analyzed by ANOVA, followed by an LSD post-hoc test, and correlations were assessed with Spearman correlation coefficient, with p < 0.05.

RESULTS

Values recorded on the lateral view were higher than those on the dorsoventral view. No differences or correlations were found between Orthopedic Foundation for Animals hip grades and temperature. Digital thermographic images showed a weak significant correlation with weight-bearing evaluations (r = 0.13, p < 0.01) and different clinical metrology instruments scores (r = - 0.25, p < 0.01 for pain severity score, and r = - 0.21, p = 0.04 for gait). It also correlated with radiographic findings, specifically the circumferential femoral head osteophyte and caudolateral curvilinear osteophyte.

CONCLUSION

To our knowledge, this is the first study presenting the digital thermography assessment of Police working dogs submitted to treatment for hip OA. Digital thermography, mainly based on a lateral view evaluation, showed a weak significant correlation with stance analysis and clinical metrology instruments scores.

Novel approach to modeling high-frequency activity data to assess therapeutic effects of analgesics in chronic pain conditions

Osteoarthritis (OA) is a chronic condition often associated with pain, affecting approximately fourteen percent of the population, and increasing in prevalence. A globally aging population have made treating OA-associated pain as well as maintaining mobility and activity a public health priority. OA affects all mammals, and the use of spontaneous animal models is one promising approach for improving translational pain research and the development of effective treatment strategies. Accelerometers are a common tool for collecting high-frequency activity data on animals to study the effects of treatment on pain related activity patterns. There has recently been increasing interest in their use to understand treatment effects in human pain conditions. However, activity patterns vary widely across subjects; furthermore, the effects of treatment may manifest in higher or lower activity counts or in subtler ways like changes in the frequency of certain types of activities. We use a zero inflated Poisson hidden semi-Markov model to characterize activity patterns and subsequently derive estimators of the treatment effect in terms of changes in activity levels or frequency of activity type. We demonstrate the application of our model, and its advance over traditional analysis methods, using data from a naturally occurring feline OA-associated pain model.

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.

Management of Osteoarthritis Using 1 Intra-articular Platelet Concentrate Administration in a Canine Osteoarthritis Model

BACKGROUND

Osteoarthritis (OA) represents a significant burden to societies, as it affects quality of life and performance and implies a large cost in terms of health care. Autologous platelets are a regenerative treatment modality for OA that are thought to be a potential stimulation of the natural healing cascade.

PURPOSE

To describe the effect of the platelet concentrate V-PET in the management of OA in a naturally occurring canine model, using several outcome assessment modalities.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 40 joints of active working police dogs with hip OA were randomly assigned to a control group (CG) and a platelet concentrate group (PCG; treatment) and evaluated. At treatment day (T0) and 8, 15, 30, 90, and 180 days after treatment, weight distribution, joint range of motion at flexion and extension, thigh girth, digital thermography, radiographic signs, 4 clinical metrology instruments, and synovial fluid interleukin 1 and C-reactive protein levels were recorded. Results were compared using repeated-measures analysis of variance with a Huynh-Feldt correction, paired-samples t test, or Wilcoxon signed rank test, with P < .05.

RESULTS

Dogs were 6.5 ± 2.4 years old (mean ± SD) and had a body weight of 26.7 ± 5.2 kg. At T0, 32 (80%) joints were graded as having mild OA, 6 (15%) as moderate, and 2 (5%) as severe. No differences were found between groups at T0. Between the PCG and CG, the symmetry index showed significant improvements in the PCG from 8 days (P = .01) to 180 days (P = .01). Joint flexion also improved in the PCG up to 90 days (P < .05) and extension improved up to 180 days (P < .01). Several clinical metrology instrument scores also improved up to 90 to 180 days after treatment. In the CG, radiographic signs progressed, while the PCG showed some improved signs. In both groups, increasing body weight and age corresponded with worse clinical and laboratory findings.

CONCLUSION

A single injection of platelet concentrate had a positive effect, lasting up to 6 months, on several clinical, imaging, and laboratory signs in a naturally occurring canine OA model.

CLINICAL RELEVANCE

We characterized the effects of this platelet concentrate in dogs, considered the gold standard of the study of OA, with a group of working animals with similar high demands as athletes.

Intraarticular triamcinolone hexacetonide, stanozolol, Hylan G-F 20 and platelet concentrate in a naturally occurring canine osteoarthritis model

Osteoarthritis (OA) is a disease transversal to all mammals, a source of chronic pain and disability, a huge burden to societies, with a significant toll in healthcare cost, while reducing productivity and quality of life. The dog is considered a useful model for the translational study of the disease, closely matching human OA, with the advantage of a faster disease progression while maintaining the same life stages. In a prospective, longitudinal, double-blinded, negative controlled study, one hundred (N = 100) hip joints were selected and randomly assigned to five groups: control group (CG, n = 20, receiving a saline injection), triamcinolone hexacetonide group (THG, n = 20), platelet concentrate group (PCG, n = 20), stanozolol group (SG, n = 20) and hylan G-F 20 group (HG). Evaluations were conducted on days 0 (T0, treatment day), 8, 15, 30, 60, 90, 120, 150 and 180 days post-treatment, consisting of weight distribution analysis and data from four Clinical Metrology Instruments (CMI). Kaplan-Meier estimators were generated and compared with the Breslow test. Cox proportional hazard regression analysis was used to investigate the influence of variables of interest on treatment survival. All results were analyzed with IBM SPSS Statistics version 20 and a significance level of p < 0.05 was set. Sample included joints of 100 pelvic limbs (of patients with a mean age of 6.5 ± 2.4 years and body weight of 26.7 ± 5.2 kg. Joints were graded as mild (n = 70), moderate (n = 20) and severe (n = 10) OA. No differences were found between groups at T0. Kaplan-Meier analysis showed that all treatments produced longer periods with better results in the various evaluations compared to CG. Patients in HG and PCG took longer to return to baseline values and scores. A higher impact on pain interference was observed in THG, with a 95% improvement over CG. PCG and HG experienced 57-81% improvements in functional evaluation and impairments due to OA, and may be a better options for these cases. This study documented the efficacy of several approaches to relieve OA clinical signs. These approaches varied in intensity and duration. HG and PCG where the groups were more significant improvements were observed throughout the follow-up periods, with lower variation in results.

The intra-articular administration of triamcinolone hexacetonide in the treatment of osteoarthritis. Its effects in a naturally occurring canine osteoarthritis model

OBJECTIVE

To evaluate the effect of an intra-articular (IA) administration of triamcinolone hexacetonide, compared with saline.

PATIENTS AND METHODS

Forty (N = 40) hip joints were randomly assigned to a treatment group (THG, n = 20, receiving IA triamcinolone hexacetonide) and a control group (CG, n = 20, receiving IA saline). On treatment day (T0), and at 8, 15, 30, 90 and 180 days post-treatment, weight distribution, joint range of motion, thigh girth, digital thermography, radiographic signs, synovial fluid interleukin-1 and C-reactive protein levels were evaluated. Data from four Clinical Metrology Instruments was also gathered. Results were compared Repeated Measures ANOVA, with a Huynh-Feldt correction, Paired Samples T-Test or Wilcoxon Signed Ranks Test. A Kaplan-Meier test was performed to compare both groups, with p<0.05.

RESULTS

Joints were graded as mild (65%), moderate (20%) and severe (15%). Patients of both sexes, with a mean age of 6.5±2.4 years and bodyweight of 26.7±5.2kg, were included. No differences were found between groups at T0. Comparing THG to CG, weight distribution showed significant improvements in THG from 8 (p = 0.05) up to 90 days (p = 0.01). THG showed lower values during thermographic evaluation in the Lt view (p<0.01). Pain and function scores also improved from 30 to 180 days. Increasing body weight, age, and presence of caudolateral curvilinear osteophyte corresponded to worse response to treatment. Results of the Kaplan Meier test showed significant differences between groups, with THG performing better considering several evaluations and scores.

CONCLUSION

THG recorded significant improvements in weight-bearing and in with the considered CMIs, particularly pain scores. Lower thermographic values were registered in THG up to the last evaluation day. Age, sex, and radiographic findings did significantly influenced response to treatment.

Intra-articular Injections With Either Triamcinolone Hexacetonide, Stanozolol, Hylan G-F 20, or a Platelet Concentrate Improve Clinical Signs in Police Working Dogs With Bilateral Hip Osteoarthritis

Objectives: To compare the effect of intra-articular treatment with triamcinolone hexacetonide (TH), stanozolol, hyaluronan, and a platelet concentrate in police working dogs with bilateral hip osteoarthritis (OA). Study Design: Prospective, longitudinal, double-blinded, negative controlled study. Sample Population: Fifty police working dogs with naturally occurring hip OA. Methods: Animals were randomly assigned to a control group (CG, n = 10), TH group (THG, n = 10), platelet concentrate group (PCG, n = 10), stanozolol group (SG, n = 10), and Hylan G-F 20 group (HG). On days 0 (T0), 8, 15, 30, 90, and 180 days post-treatment, weight-bearing distribution was evaluated. In those days, and on days 60, 120, and 150, four clinical metrology instruments were completed. Kaplan-Meier estimators were conducted and compared with the log-rank test. Cox proportional hazard regression analysis was performed to determine treatment survival. Significance was set at p < 0.05. Results: Patients had a mean age of 6.5 ± 2.4 years and body weight of 26.7 ± 5.2 kg. At T0, hips were classified as mild (n = 35), moderate (n = 10), and severe (n = 5), according to the Orthopedic Foundation for Animals grading scheme. No differences were found between groups at that moment considering age, body weight, OFA hip score, and all assessments performed. All treatments improved clinical signs in various OA dimensions in some groups, with a broad effect interval. PCG showed a lower range of variation while maintaining a positive result for more extended periods (p < 0.01 for symmetry index and 0.01 < p < 0.04 in the majority of scores). Breed, age, sex, and OFA grade did not significantly influence response to treatment. Conclusions and Clinical Relevance: This is the first prospective, negative controlled, double-blinded study to compare the effect of a single administration of these IA treatments in dogs with hip OA. HG and PCG recorded more significant improvements throughout the 180-day follow-up. In particular, PCG also registered a lower variation in results, seemingly the best therapeutic option. Nevertheless, improvements were still observed in THG and SG, and these treatment options can be considered, mainly when the first two treatments are not available.

Animal models of pain: Diversity and benefits

Chronic pain is a maladaptive neurological disease that remains a major health problem. A deepening of our knowledge on mechanisms that cause pain is a prerequisite to developing novel treatments. A large variety of animal models of pain has been developed that recapitulate the diverse symptoms of different pain pathologies. These models reproduce different pain phenotypes and remain necessary to examine the multidimensional aspects of pain and understand the cellular and molecular basis underlying pain conditions. In this review, we propose an overview of animal models, from simple organisms to rodents and non-human primates and the specific traits of pain pathologies they model. We present the main behavioral tests for assessing pain and investing the underpinning mechanisms of chronic pathological pain. The validity of animal models is analysed based on their ability to mimic human clinical diseases and to predict treatment outcomes. Refine characterization of pathological phenotypes also requires to consider pain globally using specific procedures dedicated to study emotional comorbidities of pain. We discuss the limitations of pain models when research findings fail to be translated from animal models to human clinics. But we also point to some recent successes in analgesic drug development that highlight strategies for improving the predictive validity of animal models of pain. Finally, we emphasize the importance of using assortments of preclinical pain models to identify pain subtype mechanisms, and to foster the development of better analgesics.

Clinical and diagnostic imaging findings in police working dogs referred for hip osteoarthritis

Background

Osteoarthritis (OA) is the most commonly diagnosed joint disease in veterinary medicine, with at least 80% of the cases of lameness and joint diseases in companion animals being classified as OA. Sporting and working animals are more predisposed to develop OA since they are exposed to chronic fatigue injuries, leading to bone and muscular tissue damage and failure, resulting in clinical signs. To characterize the clinical signs and diagnostic findings of Police working dogs presenting with bilateral hip OA at the time of diagnosis. Fifty animals were evaluated with a bodyweight ≥ 15 kg, be older than two years, and without any medication or nutritional supplements for ≥ 6 weeks.

Results

Weight distribution, joint range of motion at flexion and extension, thigh girth, digital thermography, and radiographic signs were collected. Data from different Clinical Metrology Instruments (CMI) were collected: Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs, Canine Orthopedic Index, and the Hudson Visual Analogue Scale. Results were compared by breed, age, sex, and Orthopaedic Foundation for Animals hip grades with the Independent Samples T-Test, ANOVA followed by a Bonferroni post hoc test, and Pearson correlation coefficient, with p < 0.05. The sample included 30 males and 20 females, with a mean age of 6.5 ± 2.4 years and a bodyweight of 26.7 ± 5.2 kg. Animals with weight distribution below normal levels had significant variations of joint extension and function scores. This evaluation was the only not correlated with at least one breed. Animals with caudolateral curvilinear osteophyte showed a poorer clinical presentation and worse scores in all considered CMIs. Radiographic changes correlated with age and corresponded to worse CMIs scores and weight distribution. Dutch Shepherd Dogs showed better CMI scores than the other considered breeds.

Conclusions

Police working dogs presented with complaints related to hip OA at an early stage of the disease. Hip scores influenced clinical presentation, with moderate cases showing lower thigh girth and worse pain interference and severity, and function scores than mild cases. Patients with severe OA had lower thermographic evaluations than patients with moderate OA. Age was the primary variable influencing considered CMI scores.

A Pilot Study on the Efficacy of a Single Intra-Articular Administration of Triamcinolone Acetonide, Hyaluronan, and a Combination of Both for Clinical Management of Osteoarthritis in Police Working Dogs

Objectives: To describe and compare the use and effectiveness of a single intra-articular injection (IA) of triamcinolone acetonide (TA), hyaluronan (HA), and a combination of both (TA+HA) in police working dogs with natural occurring hip osteoarthritis (OA).

Study Design: Prospective, randomized, single-blinded study.

Sample Population: Thirty animals with naturally occurring hip OA.

Methods: Animals were randomly divided in three groups: GT, treated with 20 mg of TA per hip joint; GH, treated with treated 20 mg of HA per hip joint; and GTH, treated with a combination of 20 mg of TA and 20 mg of HA per hip joint. Response to treatment, measured by the Canine Brief Pain Inventory (divided in Pain Interference Score—PIS and Pain Severity Score—PSS) and the Hudson Visual Analog Scale (HVAS), was evaluated in seven different time points: T0 (before treatment), T1 (after 15 days), T2, T3, T4, T5, and T6 (after 1, 2, 3, 4, and 5 months, respectively). Results were compared using a Kruskal-Wallis test or a Wilcoxon signed ranks test, and p < 0.05 was set.

Results: Comparing results of the different time points considered with T0, significant differences were registered in GH at T1 for HVAS (p = 0.03) and PIS (p = 0.04); and in GTH at T1 (p = 0.05 for HVAS and p < 0.05 for PIS), T2 (p < 0.04 for PIS), T3 (p < 0.03 for HVAS and p = 0.05 for PIS), T4 (p < 0.03 for HVAS and p < 0.05), and T5 (p < 0.05 for HVAS). No significant differences were found between groups when comparing scores in each time point. Individual treatment is considered successful with a reduction of ≥1 for PSS or ≥2 for PIS. In GTH, treatment was successful in four animals between T1 and T5 (40%, n = 10) and three at T6–T7 (30%, n = 10) for PSS and three animals of GTH at T1 (30%), two at T2 (20%), three between T3 and T4 (30%), and two between T5 and T7 (20%).

Conclusions and Clinical Relevance: This study provides direct information on the use of these treatment modalities in patients with hip OA. Intra-articular injection with TA and HA may be a treatment option for dogs with naturally occurring OA, particularly when simultaneously used, as they provide significant improvements of PIS and HVAS scores. Individual scores improved in some animals with PIS, PSS, and HVAS.

A randomized clinical efficacy study targeting mPGES1 or EP4 in dogs with spontaneous osteoarthritis

Canine studies of spontaneous osteoarthritis (OA) pain add valuable data supporting drug treatment mechanisms that may translate to humans. A multicenter, randomized, double-blind, placebo- and active-controlled study was conducted in client-owned dogs with moderate OA pain to evaluate efficacy of LYA, an inhibitor of microsomal prostaglandin E synthase-1 (mPGES1), an EP4 antagonist (LYB), and carprofen, versus placebo. Of 255 dogs screened, 163 were randomized (placebo/LYA/LYB/carprofen: n = 43/39/42/39) and 158 completed treatment. Efficacy versus placebo was assessed using Bayesian mixed-effect model for repeated measure analyses of the Canine Brief Pain Inventory (CBPI) pain interference score (PIS; primary endpoint), pain severity score, and overall impression, as well as the Liverpool Osteoarthritis in Dogs (LOAD) mobility score. The posterior probability that the difference to placebo was <0 at week 2 was 80% for LYA and 54% for LYB for CBPI PIS (both <95% predefined threshold). For secondary endpoints, the posterior probability that the difference to placebo was <0 at week 2 ranged from 89 to 96% for LYA and from 56 to 89% for LYB. The posterior probabilities comparing carprofen to placebo groups were ≥90% for all efficacy endpoints. The proportion of dogs with one or more adverse event was not significantly different from placebo (32.6%) for LYA (35.9%) or carprofen (25.6%), but the rate for LYB (59.5%) was higher versus placebo (P = 0.017). LYA treatment demonstrated consistent improvement in all efficacy measures, suggesting that inhibition of mPGES1 may be an effective treatment for chronic pain associated with OA.

Quantitative sensory testing in feline osteoarthritic pain - a systematic review and meta-analysis

Quantitative sensory testing (QST) is a psychophysical test used to quantify somatosensory sensation under normal or pathological conditions including osteoarthritis (OA).

OBJECTIVE

This study aimed to conduct a systematic review and meta-analysis of studies using QST in healthy and osteoarthritic cats, registered at Systematic Review Research Facility (#26-06-2017).

DESIGN

Hierarchical models with random intercepts for each individual study extracted through the systematic review were fit to subject-level data; QST measures were contrasted between healthy and osteoarthritic cats. Four bibliographic databases were searched; quality and risk of bias assessment were performed using pre-established criteria.

RESULTS

Six articles were included; most were of high quality and low risk of bias. Punctate tactile threshold (n = 70) and mechanical temporal summation (n = 35) were eligible for analysis. Cats with OA have lower punctate tactile threshold [mean difference (95%HDI): -44 (-60; -26) grams] and facilitated temporal summation of pain [hazard ratio (95%HDI): 5.32 (2.19; 14) times] when compared with healthy cats. The effect of sex and body weight on sensory sensitivity remained inconclusive throughout all analyses. Due to the correlation between age and OA status, it remains difficult to assess the effect of OA on sensory sensitivity, independently of age.

CONCLUSIONS

Clear and transparent reporting using guidelines are warranted. Similar to people, centralized sensitization is a feature of OA in cats. Future studies should try to elucidate the age effect on feline OA. Research with natural OA in cats is promising with potential to benefit feline health and welfare, and improve translatability to clinical research.

A report on the use of a single intra-articular administration of autologous platelet therapy in a naturally occurring canine osteoarthritis model - a preliminary study

Background

Osteoarthritis (OA) represents a significant burden to societies, as it affects quality of life, performance and poses a large healthcare cost. We aimed to describe the use of a single intra-articular (IA) injection of an autologous platelet therapy in the management of osteoarthritis (OA) in a naturally occurring canine model.

Methods

Fifteen police working dogs with bilateral hip OA were treated with 3 ml of platelet concentrate per hip joint, produced with the V-PET kit. Response to treatment was measured by the Canine Brief Pain Inventory (CBPI, divided in pain interference score – PIS, and Pain Severity Score - PSS), Liverpool Osteoarthritis in Dogs (LOAD), Canine Orthopedic Index (COI, divided in four dimensions: function, gait, stiffness and quality of life - QOL) and the Hudson Visual Analogue Scale (HVAS). Seven different time points were considered: T0 (before treatment), T1 (after 15 days), T2, T3, T4, T5 and T6 (after 1, 2, 3, 4 and 5 months respectively). Results from each evaluation moment were compared with T0 with a Paired Samples T-Test, and a p < 0.05 was set.

Results

Significant differences were observed at T1 (p < 0.01 for HVAS, PSS, COI, Gait and QOL; p = 0.01 for PIS; p = 0.02 for Function; and p < 0.05 for Stiffness), T2 (p < 0.01 for PSS, PIS and Gait; p = 0.01 for COI; p = 0.02 for HVAS, Function and QOL; and p = 0.04 for Stiffness), T3 (p < 0.01 for HVAS, PSS, PIS, Function and Gait; p = 0.01 for COI; and p = 0.02 for QOL), T4 (p < 0.01 for PSS; p = 0.03 for PIS and Gait), T5 (p < 0.01 for COI, Function and Gait; p = 0.03 for PSS, PIS and Stiffness), T6 (p < 0.01 for PSS, Function and Gait; p = 0.04 for PIS; p < 0.05 for COI) and T7 (p < 0.01 for PSS, Function and Gait; p = 0.01 for COI; and p < 0.05 for PIS).

Conclusions

Autologous platelet therapy was used without apparent harm in the subjects. A single administration produced significant improvements, which lasted several months, and therefore warrants further study.

Correlation of Artemin and GFRα3 With Osteoarthritis Pain: Early Evidence From Naturally Occurring Osteoarthritis-Associated Chronic Pain in Dogs

Arthritis, including osteoarthritis (OA) and other musculoskeletal-associated pain, is a worldwide problem, however, effective drug options are limited. Several receptors, neurotransmitters, and endogenous mediators have been identified in rodent models, but the relevance of these molecules in disease-associated pain is not always clear. Artemin, a neurotrophic factor, and its receptor, glial-derived neurotrophic factor (GDNF) family receptor alpha-3 (GFRα3), have been identified as involved in pain in rodents. Their role in OA-associated pain is unknown. To explore a possible association, we analyzed tissue from naturally occurring OA in dogs to characterize the correlation with chronic pain. We used behavioral assessment, objective measures of limb use, and molecular tools to identify whether artemin and GFRα3 might be associated with OA pain. Our results using banked tissue from well-phenotyped dogs indicates that artemin/GFRα3 may play an important, and hitherto unrecognized, role in chronic OA-associated pain. Elevated serum levels of artemin from osteoarthritic humans compared to healthy individuals suggest translational relevance. Our data provide compelling evidence that the artemin/GFRα3 signaling pathway may be important in OA pain in both non-humans and humans and may ultimately lead to novel therapeutics.

Early Neonatal Pain-A Review of Clinical and Experimental Implications on Painful Conditions Later in Life

Modern health care has brought our society innumerable benefits but has also introduced the experience of pain very early in life. For example, it is now routine care for newborns to receive various injections or have blood drawn within 24 h of life. For infants who are sick or premature, the pain experiences inherent in the required medical care are frequent and often severe, with neonates requiring intensive care admission encountering approximately fourteen painful procedures daily in the hospital. Given that much of the world has seen a steady increase in preterm births for the last several decades, an ever-growing number of babies experience multiple painful events before even leaving the hospital. These noxious events occur during a critical period of neurodevelopment when the nervous system is very vulnerable due to immaturity and neuroplasticity. Here, we provide a narrative review of the literature pertaining to the idea that early life pain has significant long-term effects on neurosensory, cognition, behavior, pain processing, and health outcomes that persist into childhood and even adulthood. We refer to clinical and pre-clinical studies investigating how early life pain impacts acute pain later in life, focusing on animal model correlates that have been used to better understand this relationship. Current knowledge around the proposed underlying mechanisms responsible for the long-lasting consequences of neonatal pain, its neurobiological and behavioral effects, and its influence on later pain states are discussed. We conclude by highlighting that another important consequence of early life pain may be the impact it has on later chronic pain states-an area of research that has received little attention.

Pet Dogs with Subclinical Acute Radiodermatitis Experience Widespread Somatosensory Sensitization

Radiation-induced dermatitis (RID) is a common and painful complication of radiotherapy. When severe, radiation-associated pain (RAP) can reduce the efficacy of radiotherapy by limiting the radiation dose given, and/or necessitating breaks in treatment. Current RAP mitigation strategies are of limited efficacy. Our long-term goal is to develop a comparative oncology model, in which novel analgesic interventions for RAP can be evaluated. The aim of this study was to validate quantitative end points indicative of RAP in pet dogs with subclinical and low-grade RID. Extremity soft tissue sarcomas were treated with post-operative irradiation (54 Gy in 18 fractions). Visual toxicity scores, questionnaire-based pain instruments and objective algometry [mechanical quantitative sensory testing (mQST)], were evaluated regularly. Breed-matched control populations were also evaluated to address the effect of potential confounders. Skin biopsies from within the irradiated field were collected at baseline and after 24 Gy irradiation, for analysis of pain-related genes using the nanoString nCounter platform. Relative to control populations, mechanical thresholds decreased in irradiated test subjects as the total radiation dose increased, with the most pronounced effect at the irradiated site. This was accompanied by increased mRNA expression of GFRα3, TNFα, TRPV2 and TRPV4. In a separate set of dogs with moderate-to-severe RID, serum concentrations of artemin (the ligand for GFRα3) were elevated relative to controls (P = 0.015). Progressive reduction in mechanical thresholds, both locally and remotely, indicates widespread somatosensory sensitization during radiation treatment. mQST in pet dogs undergoing radiation treatment represents an innovative tool for preclinical evaluation of novel analgesics.

Functional linear modeling of activity data shows analgesic-mediated improved sleep in dogs with spontaneous osteoarthritis pain

In humans, pain due to osteoarthritis has been demonstrated to be associated with insomnia and sleep disturbances that affect perception of pain, productivity, and quality of life. Dogs, which develop spontaneous osteoarthritis and represent an increasingly used model for human osteoarthritis, would be expected to show similar sleep disturbances. Further, these sleep disturbances should be mitigated by analgesic therapy. Previous efforts to quantify sleep in osteoarthritic dogs using accelerometry have not demonstrated a beneficial effect of analgesic therapy; this is despite owner-reported improvements in dogs' sleep quality. However, analytic techniques for time-series accelerometry data have advanced with the development of functional linear modeling. Our aim was to apply functional linear modeling to accelerometry data from osteoarthritic dogs participating in a cross-over non-steroidal anti-inflammatory (meloxicam) drug trial. Significant differences in activity patterns were seen dogs receiving drug (meloxicam) vs. placebo, suggestive of improved nighttime resting (sleep) and increased daytime activity. These results align with owner-reported outcome assessments of sleep quality and further support dogs as an important translational model with benefits for both veterinary and human health.

Spinal Reactive Oxygen Species and Oxidative Damage Mediate Chronic Pain in Lame Dairy Cows

Simple Summary

Chronic inflammatory diseases could impact central nervous system homeostasis, being oxidative damage of the dorsal horn, a relevant mechanism mediating central sensitization. Chronic inflammatory lameness in dairy cows is a painful condition that affects animal welfare, affecting dairy production worldwide. This study reveals increased levels of reactive oxygen species, malondialdehyde, and carbonyl groups, indicating lipid and protein damage in the spinal cord of cows with chronic lameness. Moreover, antioxidant system activity was similar between lame and non-lame cows which suggests that antioxidant dysregulation was not the cause of oxidative damage, as has been proposed previously. Based on the fact that nociceptive pathways are strongly conserved between species, there is no reason to neglect that chronic pain in cows promotes Central Nervous System (CNS) alterations, such as oxidative damage. Moreover, lame cows develop central sensitization, as allodynia and hyperalgesia are centrally and not peripherally mediated. Our results support the current assumption that chronic pain is a central nervous system disease and lameness in dairy cows is far beyond an inflammation of the hoof.

Abstract

Lameness in dairy cows is a worldwide prevalent disease with a negative impact on animal welfare and herd economy. Oxidative damage and antioxidant system dysfunction are common features of many CNS diseases, including chronic pain. The aim of this study was to evaluate the levels of reactive oxygen species (ROS) and oxidative damage markers in the spinal cord of dairy cows with chronic inflammatory lameness. Locomotion score was performed in order to select cows with chronic lameness. Dorsal horn spinal cord samples were obtained post mortem from lumbar segments (L2–L5), and ROS, malondialdehyde (MDA), and carbonyl groups were measured along with the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and total antioxidant response (TAR). Lame cows had increased levels of ROS, MDA, and carbonyl groups, while no differences were observed between lame and non-lame cows in SOD, GPx, CAT, and TAR activity. We conclude that painful chronic inflammatory lameness in dairy cows is associated with an increase in ROS, MDA, and carbonyl groups. Nonetheless, an association between ROS generation and dysfunction of the antioxidant system, as previously proposed, could not be established.

Active immunisation targeting nerve growth factor attenuates chronic pain behaviour in murine osteoarthritis

OBJECTIVES

Nerve growth factor (NGF) has emerged as a key driver of pain in osteoarthritis (OA) and antibodies to NGF are potent analgesics in human disease. Here, we validate a novel vaccine strategy to generate anti-NGF antibodies for reversal of pain behaviour in a surgical model of OA.

METHODS

Virus-like particles were derived from the cucumber mosaic virus (CuMV) and coupled to expressed recombinant NGF to create the vaccine. 10-week-old male mice underwent partial meniscectomy to induce OA or sham-surgery. Spontaneous pain behaviour was measured by Linton incapacitance and OA severity was quantified using OARSI histological scoring. Mice (experimental and a sentinel cohort) were inoculated with CuMVtt^NGF (Vax) or CuMVtt^ctrl (Mock) either before surgery or once pain was established. Efficacy of anti-NGF from the plasma of sentinel vaccinated mice was measured in vitro using a neurite outgrowth assay in PC12 cells.

RESULTS

Anti-NGF titres were readily detectable in the vaccinated but not mock vaccinated mice. Regular boosting with fresh vaccine was required to maintain anti-NGF titres as measured in the sentinel cohort. Both prophylactic and therapeutic vaccination demonstrated a reversal of pain behaviour by incapacitance testing, and a meta-analysis of the two studies showing analgesia at peak anti-NGF titres was highly statistically significant. Serum anti-NGF was able to inhibit neurite outgrowth equivalent to around 150 ug/mL of recombinant monoclonal antibody.

CONCLUSIONS

This study demonstrates therapeutic efficacy of a novel NGF vaccine strategy that reversibly alleviates spontaneous pain behaviour in surgically induced murine OA.

Long-term pain relief in canine osteoarthritis by a single intra-articular injection of resiniferatoxin, a potent TRPV1 agonist

The translational potential of analgesic approaches emerging from basic research can be augmented by client-owned dog trials. We report on a peripheral interventional approach that uses intra-articular injection of the ultrapotent TRPV1 agonist resiniferatoxin (RTX) to produce a selective long-term chemoinactivation of nociceptive primary afferent nerve endings for pain control in naturally occurring canine osteoarthritis. A single injection of 10 µg of RTX, produced suppression of pain, improvement in gait, weight bearing, and improvement in the dog's activities of daily living lasting 4 months or longer. Two to 3 years after the injection, there are no alterations to suggest that removal of inflammatory pain caused accelerated joint degeneration (Charcot joint) in any of the dogs. To amplify the effective use of canine subjects in translational analgesia research, we report a high-quality canine dorsal root ganglion transcriptome. Some targets for analgesia are highly conserved both in protein sequence and level of expression within a target tissue while others diverge substantially from the human. This knowledge is especially important for development of analgesics aimed at peripheral molecular targets and provides a template for informed translational research. The peripheral site of action, long duration of analgesia, apparent safety, and retention of coordination, all resulting from a single dose suggest that intra-articular RTX may be an effective intervention for osteoarthritis pain with few or no side effects and lead to an improved quality of life.

Characterization of gene expression in naturally occurring feline degenerative joint disease-associated pain

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Nervous system tissue from cats with painful degenerative joint disease (DJD) was analyzed.

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Gene expression was determined to investigate the neurobiological signature of DJD pain.

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There was decreased NGF and increased CX3CL1 expression in the spinal cord in DJD-affected cats compared to healthy controls.

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There was increased expression of ATF3 and CX3CL1 in dorsal root ganglia, in DJD-affected cats compared to healthy controls.

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Such studies have the potential to inform about relevant targets for the control of chronic feline pain.

Degenerative joint disease (DJD) associated-pain is a clinically relevant and common condition affecting domesticated cats and other species including humans. Identification of the neurobiological signature of pain is well developed in rodent pain models, however such information is lacking from animals or humans with naturally occurring painful conditions. In this study, identification of housekeeping genes (HKG) for neuronal tissue and expression levels of genes considered associated with chronic pain in rodent models were explored in cats with naturally occurring osteoarthritic pain. Fourteen adult cats were evaluated — seven without clinical signs of osteoarthritic pain, and seven with hind limb radiographic DJD and pain. Expression of an investigator-selected set of pain signaling genes (including ASIC3, ATF3, COX2, CX3CL1, NAV1.7, NAV1.8, NAV1.9, NGF, NK1R, TNFα, TRKA) in lumbar spinal cord dorsal horn and lumbar dorsal root ganglia tissues from clinically healthy cats and cats with DJD were studied using quantitative RT-PCR (qPCR).

HKG identified as the most stable across all tissue samples were many of the ribosomal protein genes, such as RPL30 and RPS19. qPCR results showed ATF3 and CX3CL1 up-regulated in DJD-affected dorsal root ganglia compared to clinically healthy controls. In spinal cord, CX3CL1 was up-regulated and NGF was down-regulated when DJD-affected samples were compared to healthy samples. Further work is needed to understand the neurobiology of pain in naturally occurring disease and what rodent models are predictive of these changes in more heterogeneous populations such as domestic cats.

The chondrodystrophic dog: A clinically relevant intermediate-sized animal model for the study of intervertebral disc-associated spinal pain

Low back pain (LBP) is the leading cause of disability worldwide, with an estimated 80% of the American population suffering from a painful back condition at some point during their lives. The most common cause of LBP is intervertebral disc (IVD) degeneration (IVDD), a condition that can be difficult to treat, either surgically or medically, with current available therapies. Thus, understanding the pathological mechanisms of IVDD and developing novel treatments are critical for improving outcome and quality of life in people living with LBP. While experimental animal models provide valuable mechanistic insight, each model has limitations that complicate translation to the clinical setting. This review focuses on the chondrodystrophic canine clinical model of IVDD as a promising model to assess IVD‐associated spinal pain and translational therapeutic strategies for LBP. The canine IVD, while smaller in size than human, goat, ovine, and bovine IVDs, is larger than most other small animal IVDD models and undergoes maturational changes similar to those of the human IVD. Furthermore, both dogs and humans develop painful IVDD as a spontaneous process, resulting in similar characteristic pathologies and clinical signs. Future exploration of the canine model as a model of IVD‐associated spinal pain and biological treatments using the canine clinical model will further demonstrate its translational capabilities with the added ethical benefit of treating an existing veterinary patient population with IVDD.