Synovitis in dogs with stable stifle joints and incipient cranial cruciate ligament rupture: a cross-sectional study

Cross-species analysis of genetic architecture and polygenic risk scores for non-contact ACL rupture in dogs and humans

Non-contact anterior cruciate ligament (ACL) rupture is a common serious orthopaedic disease in humans and dogs. Familial risk has been recognized in both species but interactions between genetic effects and environmental risk are not understood. We investigated ACL rupture heritability, genetic architecture, selection pressure, sharing of risk genes and biological pathways, and polygenic risk score (PRS) prediction of disease risk. In both species, ACL rupture has moderate heritability, is likely under negative selection, and has a highly polygenic architecture where thousands of variant effects act together to influence disease risk. In dogs, we found hotspots of regional heritability. We also confirmed sharing of multiple risk genes. Our findings challenge the dogma that non-contact ACL rupture is predominantly due to a single overload injury event. Our results also suggest that accurate PRS prediction of ACL rupture risk is an achievable goal in both species, enabling identification of individuals for personalized medical care.

Comparison of Cranial Cruciate Ligament Rupture Incidence among Parous and Nulliparous Rottweiler Bitches: Evidence from a Lifetime Cohort Study Supporting a Paradigm of Pregnancy-Associated Protection against Subsequent Non-Reproductive Disease Outcomes

Emerging evidence in women supports the notion that pregnancy may reset disease resistance, thereby providing protection against subsequent adverse health outcomes, but this hypothesis has not been adequately explored in domestic dogs. Cranial cruciate ligament (CCL) rupture is a degenerative orthopedic disease that frequently affects pet dogs, and its risk has been associated with disruption of the reproductive hormone axis. Our research team is conducting a lifetime cohort study of purebred Rottweilers in North America that have lived 30% longer than breed-average. Detailed medical and reproductive histories of 33 nulliparous and 32 parous Rottweilers were generated from questionnaires and review of medical records. Interviews with owners of bitches in the nulliparous group served to limit selection bias, confirming that in no instance was the reason for nulliparity based upon the owner's suspicion that a bitch had a heightened risk for CCL rupture. The risk of CCL rupture associated with parity and other exposure variables was estimated using multivariate logistic regression. Overall, CCL rupture was diagnosed in 17 of 65 (26%) bitches. Median age at first litter and CCL rupture were 3.6 and 6.5 years, respectively. Compared to nulliparous, parous bitches had a significant 94% reduction in CCL rupture risk adjusted for duration of ovary exposure, overweight body condition, dietary pattern, habitual physical activity, and work/sport activity [ORadjusted (95% CI) = 0.06 (0.01-0.46); (p = 0.006)]. The observed parity-associated CCL rupture risk reduction remained robust in sensitivity analysis excluding six nulliparous bitches for which decision not to breed was based on diagnosis of hip or elbow dysplasia, conditions which may be genetically linked to CCL rupture [ORadjusted (95% CI) = 0.08 (0.01-0.58); (p = 0.01)]. This work sets the stage for replication studies in other canine populations that should begin to explore the mechanistic basis for parity-associated CCL rupture risk reduction and to pursue other non-reproductive health outcomes in bitches whose incidence or severity may be parity-sensitive.

Outcome in 12 Dogs with Chronic Radiographic Cranial Tibial Subluxation after Tibial Plateau Leveling Osteotomy (2019-2021)

Objective

The objective of this study was to examine outcomes in dogs with cruciate ligament rupture (CR) that had chronic radiographic cranial tibial subluxation at the time of osteotomy healing after tibial plateau leveling osteotomy (TPLO). Study Design. Retrospective case analysis of 12 dogs with prospective follow-up. Four of the 12 dogs were prospectively studied 12-24 months after surgery to assess long-term radiographic and clinical outcomes.

Results

Three of the 4 dogs showed improvement in radiographic cranial tibial subluxation at long-term follow-up. In the other dog, minimally improved cranial tibial subluxation was associated with severe lameness. At long-term follow-up, gait analysis in 3 dogs with improved subluxation showed the symmetry of weight-bearing within 10% for peak vertical force, and no clinically lameness. Preoperative tibial plateau angle (TPA) and radiographic osteoarthritis in dogs with prospective follow-up and all dogs treated with TPLO surgery in the study period were not significantly different.

Conclusion

Dogs with chronic radiographic cranial tibial subluxation are acceptable candidates for TPLO. Radiographic improvement in stifle reduction may take more than 10 weeks. The dog with long-term persistent subluxation also had a higher TPA over time, suggestive of ineffective surgical correction with TPLO and treatment failure.

Identification of genetic variants associated with anterior cruciate ligament rupture and AKC standard coat color in the Labrador Retriever

Canine anterior cruciate ligament (ACL) rupture is a common complex disease. Prevalence of ACL rupture is breed dependent. In an epidemiological study, yellow coat color was associated with increased risk of ACL rupture in the Labrador Retriever. ACL rupture risk variants may be linked to coat color through genetic selection or through linkage with coat color genes. To investigate these associations, Labrador Retrievers were phenotyped as ACL rupture case or controls and for coat color and were single nucleotide polymorphism (SNP) genotyped. After filtering, ~ 697 K SNPs were analyzed using GEMMA and mvBIMBAM for multivariate association. Functional annotation clustering analysis with DAVID was performed on candidate genes. A large 8 Mb region on chromosome 5 that included ACSF3, as well as 32 additional SNPs, met genome-wide significance at P < 6.07E-7 or Log10(BF) = 3.0 for GEMMA and mvBIMBAM, respectively. On chromosome 23, SNPs were located within or near PCCB and MSL2. On chromosome 30, a SNP was located within IGDCC3. SNPs associated with coat color were also located within ADAM9, FAM109B, SULT1C4, RTDR1, BCR, and RGS7. DZIP1L was associated with ACL rupture. Several significant SNPs on chromosomes 2, 3, 7, 24, and 26 were located within uncharacterized regions or long non-coding RNA sequences. This study validates associations with the previous ACL rupture candidate genes ACSF3 and DZIP1L and identifies novel candidate genes. These variants could act as targets for treatment or as factors in disease prediction modeling. The study highlighted the importance of regulatory SNPs in the disease, as several significant SNPs were located within non-coding regions.

Correlates of estimated lifetime cruciate ligament survival inform potential rupture risk reduction strategies: findings from the Exceptional Aging in Rottweilers Study

Cranial cruciate ligament (CCL) rupture is one of the most commonly diagnosed orthopedic conditions of pet dogs, making estimated lifetime cruciate ligament survival an attractive endpoint for studies attempting to define clinical and genetic correlates of rupture risk reduction. Early life experiences contribute significantly to the origins of adult health outcomes, yet our current understanding of modifiable susceptibility factors that drive the high frequency of CCL rupture remains limited. We reasoned that combining lifetime medical history with standardized late-life assessment of lifetime cruciate ligament survival and detailed phenotyping of each dog for selected risk variables would provide a sensitive approach to identify factors that would differentiate between lifelong avoidance versus susceptibility to ligament rupture. Here, we report results of Kaplan-Meier analysis of estimated lifetime cruciate ligament survival and Cox proportional hazards modeling to assess risk variables in a lifetime cohort study of 123 purebred Rottweilers, a breed at high risk for veterinarian-diagnosed CCL rupture. We show that gonad removal during the 24-month developmental period is adversely associated with three measures of susceptibility-increased incidence of CCL rupture, multiplicity (bilateral rupture), and accelerated time to initial CCL failure. Our analysis reveals two other phenotypes-short adult height and the production of offspring (in females)-are associated with significant CCL rupture risk reduction. Together, the results provide clues to an early endocrine influence on lifetime cruciate ligament survival. Further, we identify two distinct clinical syndromes of CCL failure, providing a disease subtyping framework to advance future progress in genetic epidemiology, pathogenesis, and prediction. By conducting an evaluation of estimated lifetime CCL survival in dogs, we show that cruciate ligament survival may be jeopardized by gonad removal during the developmental period. Avoidance of such early environmental adversity may represent an actionable method for the control of canine CCL disease in certain breeds.

Comparison of Two Preoperative Radiographic Methods for Assessing Tibial Tuberosity Advancement to Achieve a Postoperative Patella Tendon Angle of 90° in Dogs

Previous studies have suggested that the preoperative methods used to plan tibial tuberosity advancement in dogs may result in under-advancement. Therefore, this cadaveric study compared the effectiveness of the common tangent method and the tibial-anatomy-based method for achieving a target patellar tendon angle (PTA) of 90° after the modified Maquet procedure. Twenty stifle joints of mesomorphic dogs were randomly assigned to the two measurement methods. Radiographs taken in the mediolateral projection were used to measure tibial tuberosity advancement, and the wedge size was selected accordingly. For each surgical procedure, a custom-made three-dimensional wedge matched to an OrthoFoam wedge was used as a spacer. Postoperative radiographs were used to measure the PTA and to evaluate the position of the wedge. The measured advancement was not significantly different between the two methods. For 60% of the cases, the advancement measured using the common tangent method was <5.3 mm and the wedge size was increased to match that of commercially available wedges. Consequently, there was a significant difference between the measurements and wedges selected between the two procedures. The postoperative PTA did not differ significantly between the two methods and was 90° ± 5° in 80% of the stifles. The position of the wedge relative to the osteotomy was not significantly different between the methods. In conclusion, the advancement determined using the tibial-anatomy-based method was generally consistent with the size of commercially available wedges, and the method yielded a mean postoperative PTA of 90°.

Degree of osteophyte formation seen on radiographs provides useful prognostic information for dogs with cruciate ligament disease

BACKGROUND

Concurrent osteoarthritis is generally present in the stifle joints of dogs with cranial cruciate ligament disease (CCLD), but it is not known if the degree of osteoarthritis-related changes affects the prognosis. Development of osteophytes is a key radiographic feature of osteoarthritis. The aim of this study was to evaluate the association between the degree of osteophyte formation seen on radiographs and CCLD-related euthanasia in dogs with CCLD.

METHODS

A retrospective cohort study including 226 dogs treated for CCLD at two university animal hospitals was performed. Clinical and follow-up information was retrieved, and stifle radiographs taken during the 31 days before treatment for the CCLD were graded for osteophyte formation by three veterinary radiologists. A multivariable Cox proportional hazards model was applied to assess the association between the degree of osteophyte formation and CCLD-related euthanasia.

RESULTS

An association between the degree of osteophyte formation and CCLD-related euthanasia was found, with increased osteophyte formation associated with an increased hazard of CCLD-related euthanasia (hazard ratio 1.06, 95% confidence interval 1.01-1.11, p = 0.01).

LIMITATIONS

No clinical assessment of the outcome was performed.

CONCLUSION

The findings suggest that evaluation of stifle radiographs for osteophyte formation could provide useful prognostic information for dogs with CCLD.

Etiopathogenesis of Canine Cruciate Ligament Disease: A Scoping Review

The spontaneous rupture of the cranial cruciate ligament in dogs remains a pathoetiologic puzzle. Despite much progress in research over the past years, the systemic and local mechanisms leading to ligament degeneration and structural failure remain largely obscure. This scoping review focuses on pathogenesis and aims at summarizing and interpreting today's knowledge on causes of canine cruciate ligament rupture, i.e., the multifactorial mechanisms leading to degenerative stifle joint disease with collagen matrix degeneration and structural failures. Thus, the initial view of traumatic ligament rupture, fostered by "wear and tear", has clearly been replaced by a new concept of systemic processes linked to progressive degenerative joint disease and ligament failure; thus, the term "cranial cruciate ligament disease" has been coined and is generally accepted. In addition, cruciate ligament rupture in people shares some similarities with the lesion in dogs; therefore, the review also includes comparative studies. The methods used were based on the PRISMA-ScR model (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews).

Arthroscopic Treatment of Chronic Cruciate Ligament Rupture in the Dog without Stifle Stabilization: 13 Cases (2001-2020)

Objective

The objective was to study clinical outcomes in dogs with chronic cruciate ligament rupture (CR) treated with palliative arthroscopy as the sole surgical treatment.

Methods

Thirteen client-owned dogs with CR underwent physical examination, stifle radiography, and arthroscopy with resection of damaged meniscal tissue. Records were evaluated, and orthopaedic examination, radiographs, and arthroscopy images were assessed. Long-term clinical outcome was also assessed by use of an owner questionnaire.

Results

Thirteen dogs that underwent arthroscopy at the UW Veterinary Care between 2001 and 2020 were included. Long-term follow-up was available for 7 of 13 dogs. Lameness was static to improved in all dogs in which arthroscopy was performed. Subsequent stifle stabilization was performed after arthroscopy in only 1 of 7 dogs with follow-up data.

Conclusion

Palliative arthroscopy and resection of damaged meniscal tissue in combination with medical management of osteoarthritis can be considered in dogs with chronic CR and cranial tibial subluxation with little passive laxity during examination. Revision surgery with TPLO is uncommon after arthroscopy based on this study.

Across-breed genetic investigation of canine hip dysplasia, elbow dysplasia, and anterior cruciate ligament rupture using whole-genome sequencing

Here, we report the use of genome-wide association study (GWAS) for the analysis of canine whole-genome sequencing (WGS) repository data using breed phenotypes. Single-nucleotide polymorphisms (SNPs) were called from WGS data from 648 dogs that included 119 breeds from the Dog10K Genomes Project. Next, we assigned breed phenotypes for hip dysplasia (Orthopedic Foundation for Animals (OFA) HD, n = 230 dogs from 27 breeds; hospital HD, n = 279 dogs from 38 breeds), elbow dysplasia (ED, n = 230 dogs from 27 breeds), and anterior cruciate ligament rupture (ACL rupture, n = 279 dogs from 38 breeds), the three most important canine spontaneous complex orthopedic diseases. Substantial morbidity is common with these diseases. Previous within- and between-breed GWAS for HD, ED, and ACL rupture using array SNPs have identified disease-associated loci. Individual disease phenotypes are lacking in repository data. There is a critical knowledge gap regarding the optimal approach to undertake categorical GWAS without individual phenotypes. We considered four GWAS approaches: a classical linear mixed model, a haplotype-based model, a binary case-control model, and a weighted least squares model using SNP average allelic frequency. We found that categorical GWAS was able to validate HD candidate loci. Additionally, we discovered novel candidate loci and genes for all three diseases, including FBX025, IL1A, IL1B, COL27A1, SPRED2 (HD), UGDH, FAF1 (ED), TGIF2 (ED & ACL rupture), and IL22, IL26, CSMD1, LDHA, and TNS1 (ACL rupture). Therefore, categorical GWAS of ancestral dog populations may contribute to the understanding of any disease for which breed epidemiological risk data are available, including diseases for which GWAS has not been performed and candidate loci remain elusive.

Canine ACL rupture: a spontaneous large animal model of human ACL rupture

Background

Anterior cruciate ligament (ACL) rupture in humans is a common condition associated with knee pain, joint instability, and secondary osteoarthritis (OA). Surgical treatment with an intraarticular graft provides reasonable outcomes at mid and long-term follow-up. Non-modifiable and modifiable factors influence risk of ACL rupture. The etiology, mechanobiology, causal biomechanics, and causal molecular pathways are not fully understood. The dog model has shared features of ACL rupture that make it a valuable spontaneous preclinical animal model. In this article, we review shared and contrasting features of ACL rupture in the two species and present information supporting spontaneous canine ACL rupture as a potentially useful preclinical model of human ACL rupture with a very large subject population.

Results

ACL rupture is more common in dogs than in humans and is diagnosed and treated using similar approaches to that of human patients. Development of OA occurs in both species, but progression is more rapid in the dog, and is often present at diagnosis. Use of client-owned dogs for ACL research could reveal impactful molecular pathways, underlying causal genetic variants, biomechanical effects of specific treatments, and opportunities to discover new treatment and prevention targets. Knowledge of the genetic contribution to ACL rupture is more advanced in dogs than in humans. In dogs, ACL rupture has a polygenetic architecture with moderate heritability. Heritability of human ACL rupture has not been estimated.

Conclusion

This article highlights areas of One Health research that are particularly relevant to future studies using the spontaneous canine ACL rupture model that could fill gaps in current knowledge.

Safety and Clinical Response Following a Repeat Intraarticular Injection of Tin-117m (117mSn) Colloid in Dogs with Elbow Osteoarthritis

Objective

To determine if a repeat intraarticular (IA) injection of a tin-117m colloid radiosynoviorthesis (RSO) agent can be safely given in the same joint 12 months after an initial injection for treatment of canine elbow osteoarthritis (OA), and to evaluate the pain reduction effect of the repeat injection.

Methods and Materials

Nine client owned dogs with grade 1 or 2 elbow OA were given an IA injection of tin-117m colloid in both elbows, one of which had been treated ≤12 months earlier with the same RSO device. Treatment safety was evaluated by joint fluid analysis at baseline (BL) and at 180 days after treatment, and by urinalysis, CBC, and serum chemistry analysis of diagnostic samples obtained at BL and 180 days. Radiographs, computed tomography, and MRI scans were obtained at BL and 180 days to determine if disease progression differed in elbows given one versus two injections. Clinical response to treatment was assessed subjectively by dog owner responses to the Canine Brief Pain Inventory (CBPI) survey at BL, 90 and 180 days, and objectively by investigator-conducted force plate (FP) analysis of dogs at BL, 90, and 180 days.

Results

All post-treatment urinalysis, CBC and clinical chemistry results were within normal ranges. Joint fluid analysis showed a significant (P=0.0411) reduction in the percentage of monocytes at 180 days, consistent with the tin-117m colloid mode of action of apoptosis of pro-inflammatory macrophages at the injection site. There was no significant difference in OA progression in elbows given one or two injections. The treatment success rate was 55.5% (5/9) on day 90 as determined either by CBPI responses or FP analysis, and 66.6% (6/9) on day 180 as determined by FP analysis.

Conclusion

The tin-117m colloid can be safely given as a repeat injection 12 months after an initial injection, and can potentially provide a durable therapeutic response in dogs with elbow OA.

Biologically Enhanced Genome-Wide Association Study Provides Further Evidence for Candidate Loci and Discovers Novel Loci That Influence Risk of Anterior Cruciate Ligament Rupture in a Dog Model

Anterior cruciate ligament (ACL) rupture is a common condition that disproportionately affects young people, 50% of whom will develop knee osteoarthritis (OA) within 10 years of rupture. ACL rupture exhibits both hereditary and environmental risk factors, but the genetic basis of the disease remains unexplained. Spontaneous ACL rupture in the dog has a similar disease presentation and progression, making it a valuable genomic model for ACL rupture. We leveraged the dog model with Bayesian mixture model (BMM) analysis (BayesRC) to identify novel and relevant genetic variants associated with ACL rupture. We performed RNA sequencing of ACL and synovial tissue and assigned single nucleotide polymorphisms (SNPs) within differentially expressed genes to biological prior classes. SNPs with the largest effects were on chromosomes 3, 5, 7, 9, and 24. Selection signature analysis identified several regions under selection in ACL rupture cases compared to controls. These selection signatures overlapped with genome-wide associations with ACL rupture as well as morphological traits. Notable findings include differentially expressed ACSF3 with MC1R (coat color) and an association on chromosome 7 that overlaps the boundaries of SMAD2 (weight and body size). Smaller effect associations were within or near genes associated with regulation of the actin cytoskeleton and the extracellular matrix, including several collagen genes. The results of the current analysis are consistent with previous work published by our laboratory and others, and also highlight new genes in biological pathways that have not previously been associated with ACL rupture. The genetic associations identified in this study mirror those found in human beings, which lays the groundwork for development of disease-modifying therapies for both species.

Analysis of copy number variation in dogs implicates genomic structural variation in the development of anterior cruciate ligament rupture

Anterior cruciate ligament (ACL) rupture is an important condition of the human knee. Second ruptures are common and societal costs are substantial. Canine cranial cruciate ligament (CCL) rupture closely models the human disease. CCL rupture is common in the Labrador Retriever (5.79% prevalence), ~100-fold more prevalent than in humans. Labrador Retriever CCL rupture is a polygenic complex disease, based on genome-wide association study (GWAS) of single nucleotide polymorphism (SNP) markers. Dissection of genetic variation in complex traits can be enhanced by studying structural variation, including copy number variants (CNVs). Dogs are an ideal model for CNV research because of reduced genetic variability within breeds and extensive phenotypic diversity across breeds. We studied the genetic etiology of CCL rupture by association analysis of CNV regions (CNVRs) using 110 case and 164 control Labrador Retrievers. CNVs were called from SNPs using three different programs (PennCNV, CNVPartition, and QuantiSNP). After quality control, CNV calls were combined to create CNVRs using ParseCNV and an association analysis was performed. We found no strong effect CNVRs but found 46 small effect (max(T) permutation P<0.05) CCL rupture associated CNVRs in 22 autosomes; 25 were deletions and 21 were duplications. Of the 46 CCL rupture associated CNVRs, we identified 39 unique regions. Thirty four were identified by a single calling algorithm, 3 were identified by two calling algorithms, and 2 were identified by all three algorithms. For 42 of the associated CNVRs, frequency in the population was <10% while 4 occurred at a frequency in the population ranging from 10–25%. Average CNVR length was 198,872bp and CNVRs covered 0.11 to 0.15% of the genome. All CNVRs were associated with case status. CNVRs did not overlap previous canine CCL rupture risk loci identified by GWAS. Associated CNVRs contained 152 annotated genes; 12 CNVRs did not have genes mapped to CanFam3.1. Using pathway analysis, a cluster of 19 homeobox domain transcript regulator genes was associated with CCL rupture (P = 6.6E-13). This gene cluster influences cranial-caudal body pattern formation during embryonic limb development. Clustered genes were found in 3 CNVRs on chromosome 14 (HoxA), 28 (NKX6-2), and 36 (HoxD). When analysis was limited to deletion CNVRs, the association was strengthened (P = 8.7E-16). This study suggests a component of the polygenic risk of CCL rupture in Labrador Retrievers is associated with small effect CNVs and may include aspects of stifle morphology regulated by homeobox domain transcript regulator genes.

Evaluation of serum MMP-2 and MMP-3, synovial fluid IL-8, MCP-1, and KC concentrations as biomarkers of stifle osteoarthritis associated with naturally occurring cranial cruciate ligament rupture in dogs

The purpose of this study was to evaluate matrix metalloproteinases (MMP) -2 and MMP-3 in serum, and keratinocyte-derived chemoattractant (KC), interleukin 8 (IL-8) and monocyte chemoattractant 1 (MCP-1) in synovial fluid (SF) as stifle osteoarthritis (OA) biomarkers in dogs. Dogs with naturally occurring cranial cruciate ligament (CrCL) rupture (OA group) and healthy controls were recruited. Stifles with CrCL deficiency were surgically stabilized. Serum, SF, and synovial biopsy samples were collected from the OA group preoperatively, whereas samples were collected once from control dogs. A blinded veterinary pathologist graded synovial biopsies. Serum and SF analyses were performed using xMAP technology. General linear regression was used for statistical comparisons of serum biomarkers, and mixed linear regression for SF biomarkers and temporal concentration changes. The overall discriminative ability was quantified using area under curve (AUC). Spearman's correlation coefficient was used to assess correlations between synovial histology grades and the biomarkers. Samples from 62 dogs in the OA group and 50 controls were included. The MMP-2 and MMP-3 concentrations between the OA and control groups were not significantly different, and both with an AUC indicating a poor discriminative ability. All three SF biomarker concentrations were significantly different between the OA group and controls (P <0.05). The MCP-1 was the only biomarker showing an acceptable discriminative performance with an AUC of 0.91 (95% confidence interval: 0.83-0.98). The sum of the inflammatory infiltrate score was significantly correlated with all three SF biomarkers (P <0.01). Summed synovial stroma, and all scores combined were significantly correlated with IL-8 and MCP-1 concentrations (P <0.003), and the summed synoviocyte scores were significantly correlated with MCP-1 concentrations (P <0.001). Correlations between MCP-1 concentrations and synovial histopathologic grading and its discriminative ability suggest its potential as a synovitis biomarker in canine stifle OA associated with CrCL rupture.

Chronic lymphoplasmacytic villonodular proliferative synovitis in a 10-year-old Jack Russell Terrier dog

We describe a case of chronic lymphoplasmacytic villonodular synovitis (CLPVNS) associated with cranial cruciate ligament (CCL) disease in a 10-year-old spayed Jack Russell Terrier bitch. The bitch was presented to a veterinary clinic with severe, non-weight bearing, acute left hindlimb lameness. The bitch had previously been treated surgically for stifle CCL disease of the same joint, using the lateral fabellar suture (LFS) technique. Since the treatment, the patient had a history of intermittent left hindlimb non-weight bearing lameness that was manageable with nonsteroidal anti-inflammatory drugs (NSAIDs). Palpation and manipulation of the affected stifle elicited severe pain. There were no other clinical or orthopaedic abnormalities. Orthogonal radiographs of the affected stifle revealed moderate degenerative joint disease and osteolytic lesions on the lateral aspect of the lateral femoral condyle and the head of the fibula. A fluid aspirate from this joint was negative for bacterial growth on culture. Cytology results were suspicious for CLPVNS. Exploratory arthrotomy, synovectomy, debridement and lavage of the affected joint were performed. Bone and synovial membrane biopsy samples of the joint were obtained and submitted to a laboratory for a histopathological confirmatory diagnosis. CLPVNS was tentatively diagnosed by cytology, and confirmed by histopathology of biopsy samples. This case report highlights the importance of checking for CLPVNS in dogs with lameness associated with CCL disease, as reports show it to be underreported or misdiagnosed.

A case report of traumatic osteoarthritis associated with LARS artificial ligament use in anterior cruciate ligament reconstruction

Background

A ligament advanced reinforcement system (LARS) artificial ligament has been proposed for use in anterior cruciate ligament (ACL) reconstruction, and many reports have shown its success in ACL reconstruction. However, there are great concerns about the potential risk of complications, which might prevent its extensive use. Late failure may occur due to serious complications.

Case presentation

We report a rare case of serious osteoarthritis that occurred 2 years postoperatively in a 51-year-old man who underwent reconstruction with an LARS artificial ligament. In X-rays, the tibial tunnel was placed too posteriorly. MRI showed that the tibial tunnel was enlarged, and there was a large effusion in the knee joint. The LARS device was rough and worn. Histologically, a large number of fibroblasts and a few multinucleated giant cells infiltrated the graft fibres.

Conclusion

Our findings remind surgeons that an LARS device should be with great caution in ACL reconstruction.

Arthroscopic Articular Cartilage Scores of the Canine Stifle Joint with Naturally Occurring Cranial Cruciate Ligament Disease

OBJECTIVE

 This study aimed to evaluate frequency, location and severity of cartilage pathology in dogs with naturally occurring cranial cruciate ligament (CCL) disease.

STUDY DESIGN

 Stifle arthroscopic video recordings (n = 120) were reviewed. A modified Outerbridge classification system (MOCS) (0-4) was used to score cartilage at 10 locations in the femorotibial (medial and lateral femoral condyles and tibial plateaus) and patellofemoral compartments (proximal, middle and distal locations of the patella and femoral trochlear groove) of the stifle joint. Synovial pathology was scored and the presence of a medial meniscal tear was recorded. A Kruskal-Wallis test was used to evaluate association of location and synovitis with cartilage score; and presence of meniscal tear with cartilage and synovitis scores. Bonferroni correction was utilized and p < 0.05 was considered significant.

RESULTS

 Cartilage pathology and synovitis were identified in all joints. Overall cartilage severity scores were low (median MOCS 1). The median MOCS of the proximal trochlear groove (2) was significantly higher than all other locations evaluated. Higher synovitis scores were significantly associated with higher cartilage severity scores and a medial meniscal tear had no association with cartilage severity scores or synovitis.

CONCLUSION

 Arthroscopic articular cartilage lesions are common in dogs with CCL disease at the time of surgical intervention, although the severity of cartilage damage is mild. The proximal trochlear groove of the femur had the most severe cartilage score in the stifle joint.

Contribution of Habitual Activity to Cruciate Ligament Rupture in Labrador Retrievers

OBJECTIVE

 The aim of this study was to describe the contribution of signalment and habitual activity in the development of cruciate ligament rupture (CR) in Labrador Retrievers.

STUDY DESIGN

 Four hundred and twelve client-owned purebred Labrador Retrievers were recruited. Dogs were assigned either as affected with CR or as controls based on signalment, physical examination and radiographic evidence of disease. Clients were asked to complete a questionnaire related to signalment, concurrent disease and a questionnaire pertaining to their dog's activity before development of CR or general activity during the dog's most active years.

RESULTS

 Habitual activity was not significantly different between dogs affected with CR and controls. There was no significant difference in neuter status or body weight between CR affected dogs and controls. Labrador Retrievers with a yellow coat, and Labradors that did not maintain an optimal body weight in the opinion of their veterinarian were at increased risk of developing CR.

CONCLUSIONS

 Habitual activity level is not a risk factor for development of CR in Labrador Retrievers. Our study did not show neuter status, sex or body weight to be risk factors for CR. However, coat colour and not sustaining optimal body condition are significant risk factors for CR.

Spontaneous dog osteoarthritis - a One Medicine vision

Osteoarthritis (OA) is a global disease that, despite extensive research, has limited treatment options. Pet dogs share both an environment and lifestyle attributes with their owners, and a growing awareness is developing in the public and among researchers that One Medicine, the mutual co-study of animals and humans, could be beneficial for both humans and dogs. To that end, this Review highlights research opportunities afforded by studying dogs with spontaneous OA, with a view to sharing this active area of veterinary research with new audiences. Similarities and differences between dog and human OA are examined, and the proposition is made that suitably aligned studies of spontaneous OA in dogs and humans, in particular hip and knee OA, could highlight new avenues of discovery. Developing cross-species collaborations will provide a wealth of research material and knowledge that is relevant to human OA and that cannot currently be obtained from rodent models or experimentally induced dog models of OA. Ultimately, this Review aims to raise awareness of spontaneous dog OA and to stimulate discussion regarding its exploration under the One Medicine initiative to improve the health and well-being of both species.

Osteoarthritis occurs spontaneously in pet dogs, which often share environmental and lifestyle risk-factors with their owners. This Review aims to stimulate cooperation between medical and veterinary research under the One Medicine initiative to improve the welfare of dogs and humans.

Dogs have many analogous spontaneous diseases that result in end-stage osteoarthritis (OA).

Inbreeding and the predisposition of certain dog breeds for OA enable easier identification of candidate genetic associations than in outbred humans.

Dog OA subtypes offer a potential stratification rationale for aetiological differences and alignment to analogous human OA phenotypes.

The relatively compressed time course of spontaneous dog OA offers longitudinal research opportunities.

Collaboration with veterinary researchers can provide tissue samples from early-stage OA and opportunities to evaluate new therapeutics in a spontaneous disease model.

Awareness of the limitations and benefits of using clinical veterinary patients in research is important.

Tibial Plateau Leveling Osteotomy for Cranial Cruciate Ligament Rupture in Canines: Patient Selection and Reported Outcomes

Cranial cruciate ligament (CCL) rupture is one of the most common causes of pelvic limb lameness in dogs. In a CCL deficient stifle, joint lameness develops from cranial tibial translation in relation to the distal femoral condyles. The tibial plateau leveling osteotomy (TPLO) is a well-described surgical procedure that neutralizes tibiofemoral shear force by altering the tibial plateau via a proximal tibial osteotomy, and subsequently restores normal limb function. Current literature for the TPLO was reviewed and used to describe the optimal patient selection and to report clinical outcome with the TPLO in comparison to other surgical options for CCL rupture. The clinical outcomes reported to date, particularly those utilizing objective outcome data, support the TPLO as being able to consistently return dogs to normal limb function with a low risk for long-term morbidity. The TPLO procedure was found to be widely applicable to dogs ranging from small breed to large and giant breed, and does not appear to have some of the limitations that exist with alternative surgical options. This review concludes that the TPLO is an excellent treatment option for any dog with CCL rupture due to the excellent long-term outcome and high rate of owner satisfaction previously reported. Despite these conclusions, it is important to remember that treatment selection for CCL rupture remains dependent on multiple considerations including patient factors, surgeon experience, and costs.

Correlation between orthopaedic and radiographic examination findings and arthroscopic ligament fibre damage in dogs with cruciate ligament rupture

OBJECTIVE

The objective is to study the correlations between physical examination and stifle radiography findings and severity of arthroscopic cranial cruciate ligament (CrCL) fibre damage in dogs with cruciate rupture (CR).

DESIGN

Design Prospective clinical study.

METHODS

Twenty-nine client-owned dogs with CR underwent physical examination, stifle radiography and arthroscopy, and the findings were recorded. Initial examination was repeated after sedation and after general anaesthesia. The Spearman rank correlations of examination variables with diagnostic imaging were examined.

RESULTS

Overall, cranial tibial translation assessed by the tibial compression test in extension showed correlation with arthroscopic CrCL fibre damage (P < 0.05). Correlations between severity of cranial drawer laxity and arthroscopic CrCL fibre damage were not significant. Under general anaesthesia, stifle laxity tests were positively correlated with lameness severity grade (S_R  ≥ 0.41, P < 0.05). Meniscal damage was correlated with pain on the internal rotation of the tibia (S_R = 0.42, P < 0.05) and severity of radiographic osteophytosis (S_R = 0.53, P = 0.01).

CONCLUSION

Detection and estimation of severity of cranial tibial translation enable the diagnosis of CR and also the inference of the severity of CrCL fibre rupture, particularly with the tibial compression test in extension. Severity of joint laxity is best assessed under general anaesthesia. Such knowledge should reduce the risk of misdiagnosis and may enhance early diagnosis and treatment of dogs with CR over time.

Extended long-term radiographic and functional comparison of tibial plateau leveling osteotomy vs tibial tuberosity advancement for cranial cruciate ligament rupture in the dog

OBJECTIVE

To report extended long-term outcomes of dogs with cranial cruciate ligament rupture treated by tibial plateau leveling osteotomy (TPLO) or tibial tuberosity advancement (TTA).

STUDY DESIGN

Retrospective clinical cohort study.

ANIMALS

Client-owned dogs with ≥3 years follow-up (118 dogs, 166 stifles).

METHODS

Records from June 2012 to May 2015 were reviewed. Follow-up examination and radiography were performed in dogs meeting the inclusion criteria. Measures of outcomes included a radiographic osteoarthritis score (preoperative, 8 weeks postoperative, and ≥3 years postoperative), the Canine Brief Pain Inventory, and the Canine Orthopedic Index.

RESULTS

Ninety-four dogs treated with TPLO (133 stifles) and 24 dogs treated with TTA (33 stifles) met the inclusion criteria. All dogs underwent meniscal release or partial medial meniscectomy. Osteoarthritis score progressed more after TTA (P = .003) and in dogs with bilateral surgery (P = .022). Long-term outcomes that were better after TPLO compared with TTA included average pain in the last 7 days (P = .007), interference with walking (P = .010), morning stiffness (P = .004), jumping (P = .003) and climbing (P = .040), limping during mild activities (P = .001), and overall quality of life (P = .045).

CONCLUSION

Osteoarthritis progressed more after TTA and in dogs with bilateral stifle surgery. Dogs treated with TPLO subjectively seemed to have less pain and fewer mobility issues.

CLINICAL SIGNIFICANCE

Tibial plateau leveling osteotomy provides a better long-term radiographic and functional outcome than TTA.

Proinflammatory polarization of stifle synovial macrophages in dogs with cruciate ligament rupture

OBJECTIVE

To determine polarization of synovial macrophages during development of cruciate ligament rupture (CR) and determine whether differences in synovial macrophage polarization in CR, osteoarthritis (OA), and healthy joints exist.

STUDY DESIGN

Prospective case-controlled study.

ANIMALS

Client-owned dogs with unstable stifles with CR (n = 22), paired stable contralateral stifles with partial CR (pCR; n = 7), joints with OA not related to CR (n = 6), and clinically normal (Normal; n = 7) joints.

METHODS

Synovial fluid samples were collected. Smears were made for differential cytology counts and estimated total nucleated cell counts. Cytospin preparations were made, and immunocytochemical staining was performed with the pan-macrophage marker CD68, M1 macrophage markers inducible nitric oxide synthase (iNOS) and chemokine (C-C motif) receptor 7 (CCR7), and M2 macrophage markers arginase 1 and CD163. Positively stained cells were counted.

RESULTS

Numbers of lymphocytes were increased in the CR group compared with the OA and Normal groups (P < .05). Numbers of CD68⁺ , CCR7⁺ , and iNOS⁺ cells in the CR and OA groups were increased compared with the Normal group (P < .05). Globally, the ratio of positively stained M1 polarized CD68⁺ cells to M2 polarized CD68⁺ cells was highest for the OA group (2.49), followed by the pCR (2.1), CR (1.63), and Normal (0.7) groups.

CONCLUSION

Polarization of synovial macrophages toward an M1 proinflammatory phenotype is an early event in the development of canine CR.

CLINICAL SIGNIFICANCE

M1 polarization in pCR stifles provides evidence of a possible role for macrophages in progressive development of cruciate ligament fiber damage. Lymphocytes may play a role in the synovitis found in CR joints. Our findings provide evidence that these cells are therapeutic targets.

High-frequency ultrasound, computed tomography and computed tomography arthrography of the cranial cruciate ligament, menisci and cranial meniscotibial ligaments in 10 radiographically normal canine cadaver stifles

BACKGROUND

Bilateral non-traumatic cranial cruciate disease is frequently seen in originally unilateral cruciate pathology. Untreated cranial cruciate ligament disease and concurrent meniscal lesions cause progressive osteoarthritis and pain of the stifle joint. Early presurgical diagnosis is important, but remains difficult. The purpose of this ex vivo study was (1) to describe the ultrasonographic appearance of the canine cranial cruciate ligament (CrCrL), menisci and meniscal ligaments using a high-frequency linear transducer, (2) to determine the length of the CrCrL seen on ultrasonography (US) and (3) to describe and compare the appearance of the CrCrL, menisci and meniscal ligaments on US, computed tomography (CT) and computed tomography arthrography (CTA).

RESULTS

US and CT examinations were performed on 10 radiographically normal cadaveric stifles of adult dogs weighing more than 15 kg, followed by macroscopic and histologic evaluations. The CrCrL had a parallel hyperechoic fibrillar pattern at the insertion on the tibia and a hypoechoic structure more proximally in all stifles. This pattern was visible over 35% (median) of the total length of the ligament, with 50% (median) of the total length CrCrL that could be outlined. All medial menisci and 8 out of 10 of the lateral menisci showed hypoechoic lines within their bodies oriented obliquely to the direction of the ultrasound beam. Fifteen of the 20 cranial meniscotibial ligaments were detected, showing a hyperechoic fibrillar pattern. Normal macro- and microscopic appearance was observed in all menisci, with the radial bundles of collagen fibers at the level of and with similar orientation as the intrameniscal hypoechoic lines on US. The CrCrL, menisci and meniscal ligaments were of intermediate density on CT, but marked improvement of the border detection was obtained using CTA. Contrast within the CrCrL was observed in 4/10 stifles using CT and confirmed in 3/4 stifles on histology. One of these ligaments had a partial tear (5-10%) on macroscopic evaluation. None of the menisci showed any abnormalities on CTA.

CONCLUSIONS

Normal canine menisci are heterogeneous on high-frequency US and a fibrillar pattern may be observed in the cranial meniscotibial ligaments and the distal portion of the CrCrL. Linear areas of contrast may be detected within the cranial cruciate ligament of radiographically normal stifles.

Multivariate genome-wide association analysis identifies novel and relevant variants associated with anterior cruciate ligament rupture risk in the dog model

Background

Anterior cruciate ligament rupture (ACLR) is a debilitating and potentially life-changing condition in humans, as there is a high prevalence of early-onset osteoarthritis after injury. Identification of high-risk individuals before they become patients is important, as post-treatment lifetime burden of ACLR in the USA ranges from $7.6 to $17.7 billion annually. ACLR is a complex disease with multiple risk factors including genetic predisposition. Naturally occurring ACLR in the dog is an excellent model for human ACLR, as risk factors and disease characteristics in humans and dogs are similar. In a univariate genome-wide association study (GWAS) of 237 Labrador Retrievers, we identified 99 ACLR candidate loci. It is likely that additional variants remain to be identified. Joint analysis of multiple correlated phenotypes is an underutilized technique that increases statistical power, even when only one phenotype is associated with the trait. Proximal tibial morphology has been shown to affect ACLR risk in both humans and dogs. In the present study, tibial plateau angle (TPA) and relative tibial tuberosity width (rTTW) were measured on bilateral radiographs from purebred Labrador Retrievers that were recruited to our initial GWAS. We performed a multivariate genome wide association analysis of ACLR status, TPA, and rTTW.

Results

Our analysis identified 3 loci with moderate evidence of association that were not previously associated with ACLR. A locus on Chr1 associated with both ACLR and rTTW is located within ROR2, a gene important for cartilage and bone development. A locus on Chr4 associated with both ACLR and TPA resides within DOCK2, a gene that has been shown to promote immune cell migration and invasion in synovitis, an important predictor of ACLR. A third locus on Chr23 associated with only ACLR is located near a long non-coding RNA (lncRNA). LncRNA’s are important for regulation of gene transcription and translation.

Conclusions

These results did not overlap with our previous GWAS, which is reflective of the different methods used, and supports the need for further work. The results of the present study are highly relevant to ACLR pathogenesis, and identify potential drug targets for medical treatment.

Electronic supplementary material

The online version of this article (10.1186/s12863-018-0626-7) contains supplementary material, which is available to authorized users.

Use of a platelet-rich plasma-collagen scaffold as a bioenhanced repair treatment for management of partial cruciate ligament rupture in dogs

Dogs are commonly affected with cruciate ligament rupture (CR) and associated osteoarthritis (OA), and frequently develop a second contralateral CR. Platelet rich plasma (PRP) is a component of whole blood that contains numerous growth factors, which in combination with a collagen scaffold may act to promote bioenhanced primary repair of ligament. This study tested the hypothesis that treatment of partial stable CR stifles with an intra-articular collagen scaffold and PRP would decrease the disease progression, synovitis and risk of complete CR over a 12-month study period. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. All dogs were treated with tibial plateau leveling osteotomy (TPLO) on the unstable stifle and a single intra-articular application of PRP-collagen in the stable partial CR stifle. Dogs were evaluated at the time of diagnosis, and at 10-weeks and 12-months after treatment. We evaluated correlation between both development of complete CR and time to complete CR with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla magnetic resonance (MR) imaging, and bilateral stifle arthroscopy. Additionally, histologic evaluation of synovial biopsies, C-reactive protein (CRP) concentrations in serum and synovial fluid, and synovial total nucleated cell count, were determined. Results indicated that a single application of PRP-collagen in partial CR stifles of client owned dogs is not an effective disease-modifying therapy for the prevention of progression to complete CR. Radiographic effusion, arthroscopic evaluation of cranial cruciate ligament (CrCL) damage, and MR assessment of ligament fiber tearing in partial CR stifles correlated with progression to complete CR over the 12-month follow-up period. We determined that the best predictive model for development of complete CR in PRP-collagen treated partial CR stifles included variables from multiple diagnostic modalities.

Effect of a single intra-articular injection of bupivacaine on synovial fluid prostaglandin E2 concentrations in normal canine stifles

Objective

To identify if synovial fluid prostaglandin E₂ increases in response to a single intra-articular dose of bupivacaine in the normal canine stifle.

Results

There were no significant differences in synovial fluid prostaglandin E₂ (PGE₂) concentrations between treatment groups or over time within bupivacaine or saline groups. Samples requiring ≥ 3 arthrocentesis attempts had significantly higher PGE₂ concentrations compared to samples requiring 1 or 2 attempts. Following correction for number of arthrocentesis attempts, PGE₂ concentrations were significantly higher than baseline at 24 and 48 h in the bupivacaine group; however there were no significant differences between the bupivacaine and saline groups. In normal dogs, a single bupivacaine injection did not cause significant synovial inflammation, as measured by PGE₂ concentrations, compared to saline controls. Future research should minimize aspiration attempts and include evaluation of the synovial response to bupivacaine in clinical cases with joint disease.

Posturography and dynamic pedobarography in lame dogs with elbow dysplasia and cranial cruciate ligament rupture

BACKGROUND

The usefulness of studying posture and its modifications due to locomotor deficiencies of multiple origins has been widely proven in humans. To assess its suitability in the canine species, static posturography and dynamic pedobarography were performed on lame dogs affected with unilateral elbow dysplasia and cranial cruciate ligament rupture by using a pressure platform. With this objective, statokinesiograms and stabilograms, the percentage of pressure distribution between limbs, paw area, mean pressure, and peak pressure, were obtained from lame and sound dogs. These data were compared with Peak Vertical Force values originated from a force platform in the same recording sessions.

RESULTS

Significant differences were found in the parameters mentioned above between sound and lame dogs and limbs.

CONCLUSIONS

Posturography and pedobarography are useful and reliable for the monitoring of fore and hindlimb lameness in dogs, providing a new set of parameters for lameness detection.

Femorotibial kinematics in dogs with cranial cruciate ligament insufficiency: a three-dimensional in-vivo fluoroscopic analysis during walking

BACKGROUND

Cranial cruciate ligament (CrCL) insufficiency is a degenerative condition that is a common cause of pelvic limb lameness and osteoarthritis in dogs. Surgical therapies developed to treat dogs with naturally occurring CrCL insufficiency aim to address the resultant instability, but the in-vivo alterations in stifle kinematics associated with CrCL insufficiency have not been accurately defined. The objective of this study was to quantify the 3-dimensional femorotibial joint kinematics of dogs with naturally occurring cranial cruciate ligament (CrCL) insufficiency during ambulation. Eighteen client-owned dogs (20-40 kg) with natural unilateral complete CrCL rupture were included. Computed tomographic scans were used to create digital 3-dimensional models of the femur and tibia bilaterally for each dog. Lateral fluoroscopic images were obtained during treadmill walking and 3 complete gait cycles were analyzed. Stifle flexion/extension angle, craniocaudal translation, and internal/external rotation were calculated throughout the gait cycle using a previously described 3D-to-2D image registration process. Results were compared between the pre-operative CrCL-deficient and 6-month post-operative contralateral stifles (control).

RESULTS

CrCL-deficient stifles were maintained in greater flexion throughout the gait cycle. Cranial tibial subluxation was evident in CrCL-deficient stifles at all time points throughout the gait cycle [9.7 mm at mid-stance (P < 0.0001); 2.1 mm at mid-swing (P < 0.0017)], and the magnitude of cranial tibial subluxation was greater at mid-stance phase than at mid-swing phase (P < 0.0001). Greater internal tibial rotation was present in CrCL-deficient stifles during stance phase (P < 0.0022) but no difference in axial rotation was evident during swing phase.

CONCLUSIONS

Naturally occurring CrCL rupture causes profound craniocaudal translational and axial rotational instability, which is most pronounced during the stance phase of gait. Surgical stabilization techniques should aim to resolve both craniocaudal subluxation and axial rotational instability.

MMP-2 as an early synovial biomarker for cranial cruciate ligament disease in dogs

Objectives: To measure the activity of matrix metalloproteinases (MMP)-2 and -9 in synovial fluid from the stifle joints of dogs with cranial cruciate ligament (CrCL) rupture and to compare that to values from contralateral stifle joints and dogs with clinically normal stifle joints. Additionally, the C-reactive protein (CRP) levels were also measured.

Methods: Fourteen large breed dogs with unilateral CrCL rupture and 11 large breed normal dogs were included in this prospective clinical study. Synovial fluid was collected from CrCL-ruptured stifle joints, contralateral clinically normal stifle joints of the same dogs, and stifle joints of normal dogs. Serum was also collected. Synovial fluid activities of MMP-2 and MMP-9 and serum CRP level were measured.

Results: The MMP-2 activity in synovial fluid was significantly higher in CrCL-ruptured joints compared to contralateral joints and to stifles from normal dogs. There was no significant difference in activity of MMP-2 in contralateral joints of CrCL-ruptured dogs compared to normal dogs. Both serum CRP level and MMP-9 activity did not differ significantly between the studied conditions.

Clinical significance: It was confirmed that MMP-2 activity is significantly related to CrCL rupture, but there was a failure to demonstrate any significant increase in the contralateral joints compared to the stifle joints of normal dogs. The MMP-2 involvement in progressing CrCL disease still has to be defined.

Incidence of complications associated with tibial tuberosity advancement in Boxer dogs

Objective: To retrospectively review and describe the incidence of complications associated with tibial tuberosity advancement (TTA) surgical procedures in a group of Boxer dogs (n = 36 stifles) and compare the data with a non-Boxer control population (n = 271 stifles).

Methods: Retrospective analysis of medical records to identify all dogs that underwent TTA surgery due to cranial cruciate ligament disease. These records were categorized into two groups: Boxer dogs and non-Boxer dogs (controls – all other breeds).

Results: Of the 307 stifles included, 69 complications were reported in 58 joints. The complication rate differed significantly for Boxer dogs (16/36 stifles) and non-Boxer dogs (42/271 stifles), corresponding to an odds ratio of 5.8 (confidence interval: 1.96–17.02; p-value <0.001). Boxer dogs were more likely to undergo revision surgery and to develop multiple complications. The incidence of tibial tuberosity fractures requiring surgical repair (2/36 versus 1/271) and incisional infections requiring antibiotic treatment (three in each group) was significantly higher in the Boxer group.

Clinical significance: Boxer dogs had more major and multiple complications after TTA surgery than the control non-Boxer group; these complications included higher rates of revision surgery, tibial tuberosity fractures requiring stabilization, and infection related complications. The pertinence and value of breed-specific recommendations for cranial cruciate ligament disease appears to be a subject worthy of further investigation.

Accuracy of 3 Tesla magnetic resonance imaging using detection of fiber loss and a visual analog scale for diagnosing partial and complete cranial cruciate ligament ruptures in dogs

Canine cranial cruciate ligament rupture is often bilateral and asymmetrical, ranging from partial to complete rupture. The purpose of our diagnostic accuracy study was to assess the accuracy of 3 Tesla magnetic resonance imaging (MRI) detection of fiber loss and use of a visual analog scale in the diagnosis of complete versus partial cranial cruciate ligament rupture in 28 clinical dogs with unilateral complete rupture and contralateral partial rupture. Three Tesla MRI was performed on 56 stifles using sagittal sequences (T2-weighted fast spin echo with fat saturation, proton density fast spin echo, and T2-weighted 3D fast spin echo CUBE). Two MRI observers assessed the cranial cruciate ligament for fiber loss and completed a visual analog scale. The MRI data were compared to arthroscopy and clinical status. Accuracy classifying partial or complete rupture was assessed using receiver operating characteristic analysis. Compared to arthroscopy, for complete cranial cruciate ligament rupture, sensitivity, specificity, and accuracy of MRI detection of fiber loss were 0.78, 0.50-0.60, and 0.68-0.71, respectively, and, for partial tears, specificity was 1.00. An MRI visual analog scale score ≥79 was indicative of complete cranial cruciate ligament rupture (sensitivity 0.72-0.94 and specificity 0.71-0.84). Using a visual analog scale cut-point ≥79, observers achieved good accuracy discriminating clinical status of partial or complete cranial cruciate ligament rupture (area under the curve 0.87-0.93). MRI evaluation for fiber loss and use of a visual analog scale are specific in stifles with clinically stable partial cranial cruciate ligament rupture. In stifles with clinically unstable complete cranial cruciate ligament rupture, both MRI tests are sensitive though not specific compared to arthroscopy. As a diagnostic imaging method, MRI may help guide treatment in patients with cranial cruciate ligament damage, particularly for stable partial rupture.

Combining a joint health supplement with tibial plateau leveling osteotomy in dogs with cranial cruciate ligament rupture. An exploratory controlled trial

Canine cranial cruciate ligament rupture (CrCLR) is a very common pathology. Surgical stabilization is the first choice treatment, although it does not fully eliminate the increased risk of osteoarthritis. This preliminary study was carried out to explore whether a newly formulated joint health supplement would benefit metabolic, clinical and radiographic changes in dogs with CrCLR surgically treated with tibial plateau leveling osteotomy (TPLO). Besides chondroitin sulfate and glucosamine hydrochloride, the studied supplement contained anti-inflammatory and antioxidant ingredients, the main ones being N-palmitoyl-D-glucosamine (Glupamid®) and quercetin. It was thus intended to target not only chondrodegenerative components of osteoarthritis, but also post-injury inflammatory response and oxidative stress of joint tissues. Thirteen dogs underwent TPLO and were randomly allocated to treatment (n = 6) and control groups (n = 7), the former receiving the joint supplement for 90 days. Lameness and radiographic osteoarthritis changes were scored before (i.e., baseline) and at 30 and 90 days post-surgery. Synovial fluid samples were collected from injured stifles at the same time points. Levels of representative metabolites were measured by proton nuclear magnetic resonance spectroscopy in a blinded fashion. In the metabolomic analysis, special attention was paid to lactate, due to its emerging recognition as a key marker of inflammation. In the last time period (from the 30th to the 90th day), lameness improved by a factor of 2.3 compared to control dogs. No significant difference was observed in the radiographic osteoarthritis score between groups. In the first postoperative month, lactate and creatine levels significantly dropped in treated compared to control dogs. Compared to surgery alone, combining the joint supplement with TPLO resulted in a trend to a better clinical outcome in the later time interval but did not influence osteoarthritis radiographic progression. A significantly better rebalance of joint microenvironment in the early time interval (baseline - 30 days) was shown by metabolomic analysis, thus suggesting that the study supplement could limit ongoing inflammatory responses.

Prior joint disease is associated with increased risk of periarticular histiocytic sarcoma in dogs

Periarticular histiocytic sarcoma (PAHS) is the most common synovial tumour in dogs and is characterized by aggressive local disease with a high rate of distant metastasis. Previously, an association between PAHS and prior joint disease has been demonstrated in the Bernese Mountain Dog breed and suggested in the Rottweiler. We hypothesized that this association would be present in other breeds and investigated this via a retrospective, case-controlled analysis. Cases were dogs diagnosed with PAHS of the stifle or elbow. Controls were age, breed and sex-matched dogs without a diagnosis of histiocytic sarcoma. Diagnosis of prior joint disease was determined based on review of medical records and direct veterinarian and owner communications. Data were evaluated using logistic regression, 2-sampled t tests, and chi-squared analysis. Our study population consisted of 28 cases and 46 controls, including Flat-Coated, Golden and Labrador Retrievers, Rottweilers, English Bulldogs, Shih Tzus, Australian Shepherds, Staffordshire Terriers and mixed breed dogs. Dogs with PAHS were more likely to have prior joint disease in the tumour-affected joint compared with the control population (odds ratio [OR] = 13.42, P < .0001, 95% confidence interval [CI] = 4.33-48.63). A total of 88.2% of dogs with stifle PAHS had prior joint disease in their tumour-affected joint, most commonly cranial cruciate ligament rupture. This study confirms that the previously noted association between prior joint disease and PAHS in Bernese Mountain Dogs also applies to other breeds. Additional studies are needed to further investigate for a causal relationship.

Radiographic and magnetic resonance imaging predicts severity of cruciate ligament fiber damage and synovitis in dogs with cranial cruciate ligament rupture

Cruciate ligament rupture (CR) and associated osteoarthritis (OA) is a common condition in dogs. Dogs frequently develop a second contralateral CR. This study tested the hypothesis that the degree of stifle synovitis and cranial cruciate ligament (CrCL) matrix damage in dogs with CR is correlated with non-invasive diagnostic tests, including magnetic resonance (MR) imaging. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. We evaluated correlation of stifle synovitis and CrCL fiber damage with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla MR imaging, and bilateral stifle arthroscopy. Histologic grading and immunohistochemical staining for CD3⁺ T lymphocytes, TRAP⁺ activated macrophages and Factor VIII⁺ blood vessels in bilateral stifle synovial biopsies were also performed. Serum and synovial fluid concentrations of C-reactive protein (CRP) and carboxy-terminal telopeptide of type I collagen (ICTP), and synovial total nucleated cell count were determined. Synovitis was increased in complete CR stifles relative to partial CR stifles (P<0.0001), although total nucleated cell count in synovial fluid was increased in partial CR stifles (P<0.01). In partial CR stifles, we found that 3D Fast Spin Echo Cube CrCL signal intensity was correlated with histologic synovitis (S_R = 0.50, P<0.01) and that radiographic OA was correlated with CrCL fiber damage assessed arthroscopically (S_R = 0.61, P<0.001). Taken together, results of this study show that clinical diagnostic tests predict severity of stifle synovitis and cruciate ligament matrix damage in stable partial CR stifles. These data support use of client-owned dogs with unilateral complete CR and contralateral partial CR as a clinical trial model for investigation of disease-modifying therapy for partial CR.

Genome-wide association analysis in dogs implicates 99 loci as risk variants for anterior cruciate ligament rupture

Anterior cruciate ligament (ACL) rupture is a common condition that can be devastating and life changing, particularly in young adults. A non-contact mechanism is typical. Second ACL ruptures through rupture of the contralateral ACL or rupture of a graft repair is also common. Risk of rupture is increased in females. ACL rupture is also common in dogs. Disease prevalence exceeds 5% in several dog breeds, ~100 fold higher than human beings. We provide insight into the genetic etiology of ACL rupture by genome-wide association study (GWAS) in a high-risk breed using 98 case and 139 control Labrador Retrievers. We identified 129 single nucleotide polymorphisms (SNPs) within 99 risk loci. Associated loci (P<5E-04) explained approximately half of phenotypic variance in the ACL rupture trait. Two of these loci were located in uncharacterized or non-coding regions of the genome. A chromosome 24 locus containing nine genes with diverse functions met genome-wide significance (P = 3.63E-0.6). GWAS pathways were enriched for c-type lectins, a gene set that includes aggrecan, a gene set encoding antimicrobial proteins, and a gene set encoding membrane transport proteins with a variety of physiological functions. Genotypic risk estimated for each dog based on the risk contributed by each GWAS locus showed clear separation of ACL rupture cases and controls. Power analysis of the GWAS data set estimated that ~172 loci explain the genetic contribution to ACL rupture in the Labrador Retriever. Heritability was estimated at 0.48. We conclude ACL rupture is a moderately heritable highly polygenic complex trait. Our results implicate c-type lectin pathways in ACL homeostasis.

Clinical features and pathological joint changes in dogs with erosive immune-mediated polyarthritis: 13 cases (2004-2012)

OBJECTIVE To evaluate the clinical features and pathological joint changes in dogs with erosive immune-mediated polyarthritis (IMPA). DESIGN Retrospective case series. ANIMALS 13 dogs with erosive IMPA and 66 dogs with nonerosive IMPA. PROCEDURES The medical record database of a veterinary teaching hospital was reviewed to identify dogs with IMPA that were examined between October 2004 and December 2012. For each IMPA-affected dog, information extracted from the medical record included signalment, diagnostic test results, radiographic findings, and treatments administered. Dogs were classified as having erosive IMPA if review of radiographs revealed the presence of bone lysis in multiple joints, and descriptive data were generated for those dogs. All available direct smears of synovial fluid samples underwent cytologic evaluation. The synovial fluid total nucleated cell count and WBC differential count were estimated and compared between dogs with erosive IMPA and dogs with nonerosive IMPA. RESULTS 13 of 79 (16%) dogs had erosive IMPA. Dogs with erosive IMPA had a mean ± SD age of 7.1 ± 2.4 years and body weight of 8.3 ± 3.4 kg (18.3 ± 7.5 lb). All 13 dogs had erosive lesions in their carpal joints. The estimated median synovial fluid lymphocyte count for dogs with erosive IMPA was significantly greater than that for dogs with nonerosive IMPA. All dogs received immunosuppressive therapy with leflunomide (n = 9), prednisone (3), or prednisone-azathioprine (1). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated erosive IMPA most commonly affected the carpal joints of middle-aged small-breed dogs. Further genetic analyses and analysis of lymphocyte-subsets are warranted for dogs with erosive IMPA.

Autologous Bone Marrow-Derived Mesenchymal Stem Cells Modulate Molecular Markers of Inflammation in Dogs with Cruciate Ligament Rupture

Mid-substance rupture of the canine cranial cruciate ligament rupture (CR) and associated stifle osteoarthritis (OA) is an important veterinary health problem. CR causes stifle joint instability and contralateral CR often develops. The dog is an important model for human anterior cruciate ligament (ACL) rupture, where rupture of graft repair or the contralateral ACL is also common. This suggests that both genetic and environmental factors may increase ligament rupture risk. We investigated use of bone marrow-derived mesenchymal stem cells (BM-MSCs) to reduce systemic and stifle joint inflammatory responses in dogs with CR. Twelve dogs with unilateral CR and contralateral stable partial CR were enrolled prospectively. BM-MSCs were collected during surgical treatment of the unstable CR stifle and culture-expanded. BM-MSCs were subsequently injected at a dose of 2x10⁶ BM-MSCs/kg intravenously and 5x10⁶ BM-MSCs by intra-articular injection of the partial CR stifle. Blood (entry, 4 and 8 weeks) and stifle synovial fluid (entry and 8 weeks) were obtained after BM-MSC injection. No adverse events after BM-MSC treatment were detected. Circulating CD8⁺ T lymphocytes were lower after BM-MSC injection. Serum C-reactive protein (CRP) was decreased at 4 weeks and serum CXCL8 was increased at 8 weeks. Synovial CRP in the complete CR stifle was decreased at 8 weeks. Synovial IFNγ was also lower in both stifles after BM-MSC injection. Synovial/serum CRP ratio at diagnosis in the partial CR stifle was significantly correlated with development of a second CR. Systemic and intra-articular injection of autologous BM-MSCs in dogs with partial CR suppresses systemic and stifle joint inflammation, including CRP concentrations. Intra-articular injection of autologous BM-MSCs had profound effects on the correlation and conditional dependencies of cytokines using causal networks. Such treatment effects could ameliorate risk of a second CR by modifying the stifle joint inflammatory response associated with cranial cruciate ligament matrix degeneration or damage.

3D FSE Cube and VIPR-aTR 3.0 Tesla magnetic resonance imaging predicts canine cranial cruciate ligament structural properties

Estimation of cranial cruciate ligament (CrCL) structural properties in client-owned dogs with incipient cruciate rupture would be advantageous. The objective of this study was to determine whether magnetic resonance imaging (MRI) measurement of normal CrCL volume in an ex-vivo canine model predicts structural properties. Stifles from eight dogs underwent 3.0 Tesla 3D MRI. CrCL volume and normalized median grayscale values were determined using 3D Fast Spin Echo (FSE) Cube and Vastly under-sampled Isotropic PRojection (VIPR)-alternative repetition time (aTR) sequences. Stifles were then mechanically tested. After joint laxity testing, CrCL structural properties were determined, including displacement at yield, yield load, load to failure, and stiffness. Yield load and load to failure (R(2)=0.56, P <0.01) were correlated with CrCL volume determined by VIPR-aTR. Yield load was also correlated with CrCL volume determined by 3D FSE Cube (R(2)=0.32, P <0.05). Structural properties were not related to median grayscale values. Joint laxity and CrCL stiffness were not related to MRI parameters, but displacement at yield load was related to CrCL volume for both sequences during testing (R(2)>0.57, P <0.005). In conclusion, 3D MRI offers a predictive method for estimating canine CrCL structural properties. 3D MRI may be useful for monitoring CrCL properties in clinical trials.

Effect of doxycycline on contralateral canine cranial cruciate ligament rupture. A prospective randomized clinical trial in 69 dogs

OBJECTIVE

To evaluate whether doxycycline administered to dogs with unilateral cranial cruciate ligament rupture (Uni-CCLR) would decrease the risk of contralateral-CCLR (Co-CCLR). To evaluate predictors for Co-CCLR survival. To evaluate if a predisposition of Labrador Retrievers to Co-CCLR exists when compared to other breeds.

METHODS

In this prospective randomized controlled clinical trial, 69 client-owned dogs with Uni-CCLR were randomly assigned to a doxycycline (group-D: 7.5 mg/kg PO BID x 6 weeks) or non-doxycycline (group-ND: negative control). Medical and imaging data, time from Uni- to Co-CCLR and to follow-up were recorded. Statistics included chi-squared test, logistic regression, Kaplan-Meier survival analysis, log rank test, survival curves, and frailty model (p <0.05).

RESULTS

This study included 32 dogs in group-D, and 37 dogs in group-ND. Median follow-up was 54.5 and 61 months, respectively. Contralateral CCLR occurred in 53.1% and 48.6% at medians of 20 and 11 months, respectively. Doxycycline did not significantly decrease the risk of Co-CCLR (p = 0.83). This risk was decreased by 14.2% with each year of age but increased with each increasing kilogram of body weight and each increasing degree of tibial plateau angle by 5.4% and 9.7%, respectively. Labrador Retrievers were not significantly predisposed (p = 0.37).

CLINICAL SIGNIFICANCE

At the dose regimen investigated doxycycline does not decrease the risk for Co-CCLR.

Fibrochondrogenic potential of synoviocytes from osteoarthritic and normal joints cultured as tensioned bioscaffolds for meniscal tissue engineering in dogs

Meniscal tears are a common cause of stifle lameness in dogs. Use of autologous synoviocytes from the affected stifle is an attractive cell source for tissue engineering replacement fibrocartilage. However, the diseased state of these cells may impede in vitro fibrocartilage formation. Synoviocytes from 12 osteoarthritic (“oaTSB”) and 6 normal joints (“nTSB”) were cultured as tensioned bioscaffolds and compared for their ability to synthesize fibrocartilage sheets. Gene expression of collagens type I and II were higher and expression of interleukin-6 was lower in oaTSB versus nTSB. Compared with nTSB, oaTSB had more glycosaminoglycan and alpha smooth muscle staining and less collagen I and II staining on histologic analysis, whereas collagen and glycosaminoglycan quantities were similar. In conclusion, osteoarthritic joint—origin synoviocytes can produce extracellular matrix components of meniscal fibrocartilage at similar levels to normal joint—origin synoviocytes, which makes them a potential cell source for canine meniscal tissue engineering.

Radiographic risk factors for contralateral rupture in dogs with unilateral cranial cruciate ligament rupture

Background

Complete cranial cruciate ligament rupture (CR) is a common cause of pelvic limb lameness in dogs. Dogs with unilateral CR often develop contralateral CR over time. Although radiographic signs of contralateral stifle joint osteoarthritis (OA) influence risk of subsequent contralateral CR, this risk has not been studied in detail.

Methodology/Principal Findings

We conducted a retrospective longitudinal cohort study of client-owned dogs with unilateral CR to determine how severity of radiographic stifle synovial effusion and osteophytosis influence risk of contralateral CR over time. Detailed survival analysis was performed for a cohort of 85 dogs after case filtering of an initial sample population of 513 dogs. This population was stratified based on radiographic severity of synovial effusion (graded on a scale of 0, 1, and 2) and severity of osteophytosis (graded on a scale of 0, 1, 2, and 3) of both index and contralateral stifle joints using a reproducible scoring method. Severity of osteophytosis in the index and contralateral stifles was significantly correlated. Rupture of the contralateral cranial cruciate ligament was significantly influenced by radiographic OA in both the index and contralateral stifles at diagnosis. Odds ratio for development of contralateral CR in dogs with severe contralateral radiographic stifle effusion was 13.4 at one year after diagnosis and 11.4 at two years. Odds ratio for development of contralateral CR in dogs with severe contralateral osteophytosis was 9.9 at one year after diagnosis. These odds ratios were associated with decreased time to contralateral CR. Breed, age, body weight, gender, and tibial plateau angle did not significantly influence time to contralateral CR.

Conclusion

Subsequent contralateral CR is significantly influenced by severity of radiographic stifle effusion and osteophytosis in the contralateral stifle, suggesting that synovitis and arthritic joint degeneration are significant factors in the disease mechanism underlying the arthropathy.

Evaluation of the radiographic infrapatellar fat pad sign of the contralateral stifle joint as a risk factor for subsequent contralateral cranial cruciate ligament rupture in dogs with unilateral rupture: 96 cases (2006-2007)

OBJECTIVE

To determine prevalence of the contralateral radiographic infrapatellar fat pad sign and contralateral radiographic degenerative sign (degenerative changes) and evaluate both signs as risk factors for subsequent contralateral cranial cruciate ligament (CrCL) rupture in dogs with unilateral CrCL rupture.

DESIGN

Retrospective cohort study.

ANIMALS

96 dogs with unilateral CrCL rupture and 22 dogs with bilateral CrCL rupture.

PROCEDURES

Dogs with unilateral CrCL rupture were classified as having normal (n = 84) or abnormal (12) contralateral stifle joints on the basis of joint palpation. Associations between potential predictive variables and rates of subsequent contralateral CrCL rupture were evaluated.

RESULTS

Of the 84 dogs with unilateral CrCL rupture in which the contralateral stifle joint was palpably normal, 29 (34.5%) had a contralateral fat pad sign and 31 (36.9%) had a degenerative sign. All dogs with unilateral CrCL rupture in which the contralateral stifle joint was palpably abnormal had a contralateral fat pad sign and degenerative sign. The contralateral fat pad sign was the most important risk factor for subsequent rupture of the contralateral CrCL. For dogs with unilateral CrCL rupture and palpably normal contralateral stifle joint with and without a contralateral fat pad sign, median time to subsequent rupture was 421 and 1,688 days, respectively, and the 3-year probability of subsequent rupture was 85.3% and 24.9%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Bilateral stifle joint radiography should be performed for all dogs with CrCL rupture. Bilateral stifle joint arthroscopy should be considered for dogs with a contralateral fat pad sign.

Arthroscopic assessment of stifle synovitis in dogs with cranial cruciate ligament rupture

Cranial cruciate ligament rupture (CR) is a degenerative condition in dogs that typically has a non-contact mechanism. Subsequent contralateral rupture often develops in dogs with unilateral CR. Synovitis severity is an important factor that promotes ligament degradation. Consequently, we wished to evaluate the utility of arthroscopy for assessment of stifle synovitis in dogs with CR. Herein, we report results of a prospective study of 27 dogs with unilateral CR and bilateral radiographic osteoarthritis. Arthroscopic images and synovial biopsies from the lateral and medial joint pouches were obtained bilaterally and graded for synovial hypertrophy, vascularity, and synovitis. Synovial tartrate-resistant acid phosphatase-positive (TRAP+) macrophages, CD3(+) T lymphocytes, Factor VIII+ blood vessels, and synovial intima thickness were quantified histologically and related to arthroscopic observations. Risk of subsequent contralateral CR was examined using survival analysis. We found that arthroscopic scores were increased in the index stifle, compared with the contralateral stifle (p<0.05). Numbers of CD3+ T lymphocytes (SR = 0.50, p<0.05) and TRAP+ cells in joint pouches (SR = 0.59, p<0.01) were correlated between joint pairs. Arthroscopic grading of vascularity and synovitis was correlated with number density of Factor VIII+ vessels (SR>0.34, p<0.05). Arthroscopic grading of villus hypertrophy correlated with numbers of CD3(+) T lymphocytes (SR = 0.34, p<0.05). Synovial intima thickness was correlated with arthroscopic hypertrophy, vascularity, and synovitis (SR>0.31, p<0.05). Strong intra-observer and moderate inter-observer agreement for arthroscopic scoring was found. Dog age and arthroscopic vascularity significantly influenced risk of contralateral CR over time. We conclude that arthroscopic grading of synovitis is a precise tool that correlates with histologic synovitis. Arthroscopy is useful for assessment of stifle synovitis in client-owned dogs, and could be used in longitudinal clinical trials to monitor synovial responses to disease-modifying therapy.