Comparison of the distraction index and Norberg angle with radiographic grading of canine hip dysplasia.

The Orthopedic Foundation for Animals (OFA) radiographic grading system stands as a well-established benchmark for categorizing hip dysplasia in canines. Although more objective techniques to quantify early hip laxity in young dogs, such as the Norberg angle (NA) and distraction index (DI), have been documented, there is a scarcity of published studies that directly compare these radiographic measures. The primary objectives of this prospective, analytical study were to assess and compare the NA and DI measures with OFA grades within a cohort of dogs. Thirty dogs (57 hip joints) were evaluated, with a mean age of 5.4 ± 2.9 years and a mean body weight of 34.3 ± 7.1 kg. The discriminative power of hip dysplasia for DI and NA used OFA as a reference were compared by multivariate discriminant analysis test. Using the DI (≤0.3) 12 joints were classified as normal, using NA (≥105°) 24 joints and using OFA (≤3) 29. When comparing the discriminant power of NA with OFA resulting similar (P = .8324) with correct classifications of 81% using cross validation, however, the discriminant power of dysplasia of the DI resulted significantly greater (P = .0034) than OFA with correct classifications of only 59% using cross-validation, consequently it was possible determined that of 29 patients with OFA ≤ 3, 20 had DI > 0.3. These findings demonstrated that phenotypic healthy dogs according to OFA grading can present passive hip joint laxity, as demonstrated by radiographic evaluation with distraction. Furthermore, DI can contribute to the screening of CHD when evaluated in conjunction with OFA grading.

Mechanical osteoarthritis of the hip in a one medicine concept: a narrative review.

Human and veterinary medicine have historically presented many medical areas of potential synergy and convergence. Mechanical osteoarthritis (MOA) is characterized by a gradual complex imbalance between cartilage production, loss, and derangement. Any joint instability that results in an abnormal overload of the joint surface can trigger MOA. As MOA has a prevailing mechanical aetiology, treatment effectiveness can only be accomplished if altered joint mechanics and mechanosensitive pathways are normalized and restored. Otherwise, the inflammatory cascade of osteoarthritis will be initiated, and the changes may become irreversible. The management of the disease using non-steroidal anti-inflammatory drugs, analgesics, physical therapy, diet changes, or nutraceuticals is conservative and less effective. MOA is a determinant factor for the development of hip dysplasia in both humans and dogs. Hip dysplasia is a hereditary disease with a high incidence and, therefore, of great clinical importance due to the associated discomfort and significant functional limitations. Furthermore, on account of analogous human and canine hip dysplasia disease and under the One Medicine concept, unifying veterinary and human research could improve the well-being and health of both species, increasing the acknowledgement of shared diseases. Great success has been accomplished in humans regarding preventive conservative management of hip dysplasia and following One Medicine concept, similar measures would benefit dogs. Moreover, animal models have long been used to better understand the different diseases' mechanisms. Current research in animal models was addressed and the role of rabbit models in pathophysiologic studies and of the dog as a spontaneous animal model were highlighted, denoting the inexistence of rabbit functional models to investigate therapeutic approaches in hip MOA.

Patellar development after patella instability and early reduction in growing rabbits.

BACKGROUND: Patella-shaped disorder has been considered as a predisposing factor for patella instability. But the influence of early patella reduction for patellar development remains unclear. This study aimed to evaluate whether early operation in patella instability could improve patella morphology in growing rabbits. METHODS: Fifty rabbits (1-month-old) were included in the study. The control group underwent no surgical procedures. The two experimental groups (reduction group and non-reduced group), underwent medial soft tissue restraint release surgery. The reduction group, rabbits underwent the medial soft tissue sutura surgery in order to stabilize the patella 2 months after release surgery. The non-reduced group, rabbits did not undergo suture surgery. Computed Tomography (CT) scans analysis in two experimental endpoints (2, 5 months after release surgery) were selected to evaluate the transverse diameter, thickness, Wiberg index and Wiberg angle. Gross observation was conducted to assess morphological changes of the patella. RESULTS: CT scans showed significant difference in the mean transverse diameter, Wiberg angle between the two experimental groups and the control group 2 months after release surgery. 5 months after release surgery, the indices of patella were found no statistically difference in the reduction group versus the control group. However, the transverse diameter, Wiberg angle in the non-reduced group were significantly differences than that in the reduction group (P < 0.05). Gross observation showed a flattened articular surface of the patella in the non-reduced group. CONCLUSIONS: The results indicated that patella instability may lead to patella-shaped disorder, showing a flattened morphology. Early patella reduction can improve the patella morphology in growing rabbits.

Comparison of two postoperative complication grading systems after treatment of stifle and shoulder instability in 68 dogs.

OBJECTIVE: (1) To adapt and apply the Clavien-Dindo (aCD) postoperative complication grading system to dogs experiencing complications following a single orthopedic procedure. (2) To compare the reliability of the Clavien-Dindo system to the Cook complication grading system. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Sixty-eight client-owned dogs. METHODS: Scenarios derived from complications following TightRope stabilization of the stifle and shoulder were graded by four ACVS-boarded surgeons using two systems; the Cook 3-point scale and the aCD 5-point scale. Because the aCD system distinguishes complications from outcomes ("sequelae" or "failure to cure"), two data sets were created: one with (n = 76) and without (n = 67) inclusion of "sequelae" and "failure to cure" cases. Interobserver reliability was evaluated using intraclass correlation coefficient (ICC) calculations. RESULTS: Seventy-six scenarios from 68 records were evaluated. The ICC of the aCD system was 0.620 consistent with moderate reliability. The reliability of the Cook system was good, with an ICC of 0.848. Exclusion of cases with "sequelae" or "failure to cure" resulted in excellent reliability of the aCD system (ICC = 0.975) and good reliability of the Cook systems (ICC = 0.857). CONCLUSION: The aCD grading system was less reliable than the Cook system when evaluating all cases but more reliable when evaluating cases of complications excluding "sequelae" and "failures to cure". CLINICAL SIGNIFICANCE: The Cook grading system is reliably good in grading postoperative complications in dogs. The aCD system can also be used to assess postoperative complications with excellent reliability but is less reliable when distinguishing complications from other postoperative outcomes.

Pilot study of the ultrasonographic examination of the intact and transected medial glenohumeral ligament in dogs.

Medial glenohumeral ligament injury is commonly reported during medial shoulder joint instability in dogs. Arthroscopy is considered the gold standard procedure, but it is invasive and requires distension of the joint. Ultrasonographic examination of the medial glenohumeral ligament has been studied as a possible, less invasive alternative to arthroscopy however it has not been considered a useful method of assessment due to the interference of the probe with the pectoral muscles. The aims of this prospective analytical randomized pilot study were to develop a standardized ultrasound protocol for visualizing the canine medial glenohumeral ligament and to compare goniometry and ultrasound findings in cadaver dogs with versus without transection of the medial glenohumeral ligament. Nine adult Beagle cadavers (18 shoulders) were used. The first six shoulders were used in a preliminary study to describe an ultrasound technique to identify the medial glenohumeral ligament. Arthroscopy was performed on the remaining 12 shoulders, with six randomly selected medial glenohumeral ligaments from these shoulders, transected during the procedure. Ultrasound examination was performed after each arthroscopic procedure by an ultrasonographer blinded to the patient group. Four medial glenohumeral ligaments (67%) were correctly identified during the preliminary study. Ultrasonographic examination failed to diagnose the transection of all six medial glenohumeral ligaments in the second part of the study. No difference was observed in the ligament thickness between the dogs with and without a transected medial glenohumeral ligament. Dogs with a transected medial glenohumeral ligament had a wider articular space compared to dogs without a transected ligament (P < 0.001), and an articular space wider than 8.2 mm was discriminatory of a transected medial glenohumeral ligament in all the shoulders. In conclusion, the medial glenohumeral ligament could be identified with a medial ultrasonographic approach of the shoulder and a wider articular space can be a sign of a medial shoulder joint instability. Further studies are needed to confirm these preliminary findings in living dogs, with and without shoulder instability.

Comparison of cross-sectional area and fat infiltration of suboccipital muscles between normal dogs and dogs with atlantoaxial instability.

BACKGROUND: Atlantoaxial instability (AAI) is primarily a congenital neurological disorder affecting young toy-breed dogs. So far, most studies have focused on bones and ligaments related to AAI, and there are no studies on the suboccipital muscles (SOMs) that occupy a large area from the occipital bone to C2 in dogs. This study evaluated the cross-sectional area (CSA) and fat infiltration of the SOMs using magnetic resonance imaging (MRI), specifically, T1-weighted images, in normal dogs (≤ 5 kg) and AAI dogs. The relationship between the severity of the neurological symptoms of AAI (group A and group B) and the values from MRI was also assessed. RESULTS: AAI dogs had significantly smaller CSA (P = 0.029) and greater fat infiltration (P = 0.044) of the SOMs compared to normal dogs. AAI dogs with mild neurological symptoms for a long period (group A) had greater fat infiltration than AAI dogs with severe neurological symptoms (group B) (P = 0.035). CONCLUSIONS: The muscle changes are most likely due to spinal cord compression resulting from instability; however, the possibility that chronic changes of the muscle may play an additional role in maintaining stability in this region cannot be excluded. This study provides fundamental quantitative information of the SOMs in normal and AAI dogs.

Determination of cutoff values on computed tomography and magnetic resonance images for the diagnosis of atlantoaxial instability in small-breed dogs.

OBJECTIVE: To determine cutoff values for the diagnosis of atlantoaxial instability (AAI) based on cross-sectional imaging in small-breed dogs. STUDY DESIGN: Retrospective multicenter study. SAMPLE POPULATION: Client-owned dogs (n = 123) and 28 cadavers. METHODS: Dogs were assigned to three groups: a control group, a "potentially unstable" group, and an AAI-affected group, according to imaging findings and clinical signs. The ventral compression index (VCI), cranial translation ratio (CTR), C1-C2 overlap, C1-C2 angle, atlantoaxial distance, basion-dens interval, dens-to-axis length ratio (DALR), power ratio, and clivus canal angles were measured on CT or T2-weighted magnetic resonance (MR) images. Receiver operating characteristic (ROC) analysis was performed to define cutoff values in flexed (≥25°) and extended (<25°) head positions. RESULTS: Cutoff values for the VCI of ≥0.16 in extended and ≥0.2 in flexed head positions were diagnostic for AAI (sensitivity of 100% and 100%, specificity of 94.54% and 96.67%, respectively). Cutoff values for the other measurements were defined with a lower sensitivity (75%-96%) and specificity (70%-97%). A combination of the measurements did not increase the sensitivity and specificity compared with the VCI as single measurement. CONCLUSION: Cutoff values for several imaging measurements were established with good sensitivity and specificity. The VCI, defined as the ratio between the ventral and dorsal atlantodental interval, had the highest sensitivity and specificity in both head positions. CLINICAL SIGNIFICANCE: The use of defined cutoff values allows an objective diagnosis of AAI in small-breed dogs. The decision for surgical intervention, however, should remain based on a combination of clinical and imaging findings.

Reconstruction of the cranial cruciate ligament using a semitendinosus autograft in a lapine model.

OBJECTIVE: To clarify and improve a cranial cruciate ligament (CrCL) deficient stifle stabilization technique using a semitendinosus tendon (ST) autograft fixed with an interference fit screw (IFS) in a closed-joint trauma lapine osteoarthritis (OA) model. STUDY DESIGN: Experimental OA model. ANIMALS: Forty-one Flemish Giant rabbits. METHODS: Following arthrotomy of traumatized lapine stifles, the ST insertion on the tibial plateau was exposed and the ST was transected near its origin. The graft was passed through tibial and femoral tunnels, manually tensioned and then secured in place with a custom IFS and periosteal sutures. Drawer was manually assessed during and immediately after surgery intraoperatively. Upon euthanasia, joint laxity was measured at 2, 10, or 22 weeks postoperatively and compared to that of the contralateral, intact stifles and stifles with a surgically transected CrCL. RESULTS: Minimal postoperative drawer was present in 34% of the rabbits and potentially correlated with meniscal injury and subsequent meniscectomy. CrCL reconstruction significantly reduced joint laxity to a level (3.6 ± 1.6 mm) similar to that (2.7 ± 0.8 mm) in contralateral intact stifles. CONCLUSION: Surgical replacement of a traumatically injured CrCL using a ST autograft fixed with an IFS replicated a common human surgical technique and effectively restored joint stability in the short, medium, and long terms of the study. CLINICAL SIGNIFICANCE: The study provides researchers a useful, clinically relevant, post-traumatic CrCL deficient rabbit model for the study of OA and investigations of interventions to mitigate or prevent long-term joint degeneration.

Dorsal Atlantoaxial Ligament Hypertrophy as a Cause for Clinical Signs in Dogs with Dens Abnormalities.

The objective of this study is to suggest clinical and subclinical atlantoaxial (AA) instability as a cause for dorsal AA ligament hypertrophy responsible for clinical signs in dogs with dens abnormalities. Clinical information from five dogs with malformed dens and dorsal spinal cord compression at the AA junction was collected. All dogs had neck pain, associated with tetraparesis in three cases. Radiological examination revealed hypoplastic dens in two dogs and a defect in its ossification in the other three. Stress views were able to demonstrate obvious AA instability only in two cases, but it was suspected in the other owing to response to surgical fixation of the joint and the presence of a dorsal compressive band, which was considered an enlarged dorsal AA ligament. Surgical and histopathological examination of compressive tissue confirmed hypertrophy of the ligament. Long-term prognosis in the four operated cases, either by dorsal decompression and ventral fixation or by ventral fixation alone, was excellent. A malformed dens can cause subclinical instability, unnoted in dynamic studies. As instability may lead to hypertrophy of joint ligaments, soft tissue changes (specifically dorsal AA ligament hypertrophy) points out this instability and the need for joint fixation if surgical management is required.

Comparison of classic and needle arthroscopy to diagnose canine medial shoulder instability: 31 cases.

This retrospective study compared surgery time, anesthesia time, and costs recorded with classic arthroscopy or needle arthroscopy when diagnosing canine medial shoulder instability. Signalment, examination findings, diagnostics, anesthesia time, surgery time, treatment, invoices, and complications were reported. All cases (classic arthroscopy, 14 cases; needle arthroscopy, 17 cases) were diagnosed with medial shoulder instability. Anesthesia times, surgery times, and invoices were statistically compared for classic and needle arthroscopy (P < 0.05). No significant differences were reported for surgery time (P = 0.13) but existed for anesthesia time (35 minutes shorter with needle arthroscopy; P < 0.0001) and invoice (38% lower with needle arthroscopy; P < 0.0001). No complications were recorded by the time of last direct follow-up, which was at a mean of 12.4 weeks after surgery. Needle arthroscopy offers an alternative, safe technique to reliably diagnose canine medial shoulder instability. Shorter anesthesia times and lower costs to the client may be advantages of needle over classic arthroscopy.

Comparaison de l'arthroscopie classique à l'arthroscopie l'aiguille pour diagnostiquer l'instabilité médiale de l'épaule chez le chien : 31 cas. Cette étude rétrospective a comparé le temps de chirurgie et d'anesthésie ainsi que les coûts engendrés entre une arthroscopie classique et une arthroscopie à l'aiguille lors du diagnostic de l'instabilité médiale de l'épaule chez le chien. Sont rapportés dans cette étude, les commémoratifs, les résultats de l'examen clinique, les diagnostics, le temps d'anesthésie, le temps de chirurgie, le traitement, les coûts et les complications. Le temps d'anesthésie et de chirurgie ainsi que leur coût ont été comparés pour les deux techniques arthroscopie classique et arthroscopie à l'aiguille (P < 0,05) pour tous les cas diagnostiqués avec une instabilité médiale de l'épaule (classique = 14; aiguille = 17). Aucune différence significative n'a été mise en évidence pour la durée de la chirurgie (P = 0,13) à contrario de la durée de l'anesthésie, plus courte (35 min de moins avec la technique à l'aiguille; P < 0,0001) et moins coûteuse (38 % plus économique avec la technique à l'aiguille; P < 0,0001). Aucune complication n'a été enregistrée lors de la dernière consultation de contrôle post-opératoire qui avait lieu en moyenne 12,4 semaines après la chirurgie. Pour diagnostiquer une instabilité médiale de l'épaule, la technique à l'aiguille offre une alternative sûre, avec comme avantages, des durées d'anesthésie plus courtes et des coûts inférieurs pour le client, par rapport à la technique classique.(Traduit par les auteurs).

Flexed radiographic angles for determination of atlantoaxial instability in dogs.

OBJECTIVE: To determine a flexed position for radiographic diagnosis of atlantoaxial instability (AAI) and to identify radiographic measurement cutoffs to differentiate affected dogs from neurologically healthy toy breeds. STUDY DESIGN: Retrospective case series and prospective case controls. ANIMALS: Thirty-nine client-owned toy breed dogs in which AAI had been diagnosed and 20 neurologically healthy client-owned toy breed dogs. METHODS: Medical records from three institutions were retrospectively reviewed to identify dogs affected with AAI. Flexed lateral images were reviewed, and measurements were obtained by using anatomic landmarks. Radiography was performed with control dogs to obtain the same measurements. RESULTS: Flexed lateral radiographs of thirty dogs affected with AAI were found to be positioned at a mean of 51° flexion. When flexed lateral radiographs were evaluated with a cutoff value for atlas to axis angle (AAA) >10°, evaluation of all breeds represented revealed a 90% sensitivity and 90% specificity. When this cutoff was evaluated in Yorkshire terriers, Chihuahuas, and mixes of these breeds, the sensitivity was 92%, and the specificity was 92%. When the control sample was positioned at 51° ± 10°, only two of the dogs were within the AAA cutoff value of >10°. There was no difference between the measurements obtained by using the flexed lateral view (mean = 50.9°) and the exaggerated flexed lateral view (mean = 38.9°) in the control sample. CONCLUSION: This study established objective measurements for the positioning and diagnosis of AAI on flexed lateral radiographs in toy breed dogs. CLINICAL SIGNIFICANCE: Atlantoaxial instability can be objectively diagnosed in sedated or anesthetized toy breed dogs when applying 51° flexion to cervical radiographs.

A novel patient-specific drill guide template for stabilization of thoracolumbar vertebrae of dogs: cadaveric study and clinical cases.

OBJECTIVE: To evaluate the accuracy and safety of a novel patient-specific drill guide template for stabilizing the thoracolumbar vertebrae of dogs. STUDY DESIGN: Cadaveric experimental study and prospective case series. SAMPLE POPULATION: Cadaveric canine thoracolumbar vertebral specimens (n = 3) and clinical cases of thoracolumbar spinal instability (n = 4). METHODS: Computed tomography data of the thoracolumbar spines were obtained before surgery, and images were imported into imaging software. Optimum screw trajectories were selected for each vertebra, and drill guide templates were designed and fabricated with a 3-dimensional printing system. Drill guide templates were applied to cadaveric spine and clinical cases. Computed tomography imaging was performed after surgery, and planned and postoperative trajectories were compared to estimate the accuracy and safety of the drill guide templates. RESULTS: Twenty-two drill holes were made in cadaveric spinal specimens. All drill holes were completely located in the bone. The overall mean screw deviation was 0.88 ± 0.36 mm. In clinical cases, 29 screws were placed in thoracolumbar vertebrae. Most (89.6%) of these screws were placed without evidence of vertebral canal invasion. One (3.5%) screw perforated the bone structure. The overall mean screw deviation was 1.16 ± 0.56 mm. CONCLUSION: Drill guide templates were useful for accurate intraoperative screw navigation in thoracolumbar fixation in small dogs. CLINICAL SIGNIFICANCE: The use of drill guide templates can be considered as an aid to safety and accuracy of screw placement in canine thoracolumbar instabilities.

Ligament Laxity in Nonerosive Immune-Mediated Polyarthritis in Dogs: Five Cases (2009-2017).

Ligament laxity is a known complication of erosive immune-mediated polyarthritis (IMPA) in dogs. The purpose of this study was to describe the occurrence and clinical features of carpal or tarsal ligament laxity in cases of nonerosive IMPA in dogs for the first time. Five client-owned dogs with a diagnosis of nonerosive IMPA and carpal or tarsal ligament laxity in which the influence of corticosteroids was excluded were identified. Medical records were reviewed, and data including signalment, investigative findings, and treatment regimen (e.g., surgical management) was extracted. Primary care practices were contacted to obtain follow-up, and the data was descriptively analyzed. The affected joints were either carpi and tarsi (n = 3) or carpi only (n = 2). In three cases, surgical arthrodesis was performed. Three dogs were euthanized (1 mo, 12 mo, and 5 yr) as a result of the severity of clinical signs and poor control. In the four dogs surviving >6 mo, multiple episodes of relapse were recorded, and multimodal immunosuppression was needed. The prognosis for the dogs described was poor, with none achieving control of the disease without ongoing immunosuppressive therapy. Damage to soft-tissue periarticular structures may be related to prolonged clinical disease or a more severe presentation. Jaccoud's arthropathy in humans with systemic lupus erythematosus may represent a homologous presentation.

Ulnar ostectomy decreases the stability of canine cadaver carpi as assessed with stress radiography.

Distal ulnar ostectomy may be performed palliatively in patients with distal ulnar osteosarcoma. Concurrent arthrodesis of the carpus has been proposed to counteract joint instability following transection of carpal ligaments associated with removal of the distal ulna. The objective of this prospective one group pretest, posttest study was to assess stability of the carpus following distal ulnar ostectomy using pre- and postoperative stress radiographic views in a group of canine cadaver limbs. Seven thoracic limbs from six canine cadavers weighing more than 20 kg were obtained. Lateral and dorsopalmar, extended lateral, medial stress, and lateral stress radiographs were made before and after distal ulnar ostectomy. Presurgical canine cadaver carpal angle measurements were as follows (mean ± standard deviation): extension 205.9° ± 5.4; medial stress 25.1° ± 5.7; and lateral stress 13.3° ± 5.2°. Cadaver limb joint angles exceeded those previously reported in live dogs. A significant increase in carpal angle was noted following ulnar ostectomy. The mean increases in carpal angle were as follows: (mean ± standard deviation (95% confidence interval)): extension 6.2° ± 4.9 (2.6-9.8) (P = 0.007); medial stress 3.2° ± 3.0 (1.0-5.5) (P = 0.015); lateral stress 6.2° ± 5.2 (2.4-10.1) (P = 0.010). Findings from this cadaver study support the use of supplementary stabilization for clinical patients undergoing distal ulnar ostectomy. Future studies are needed in clinical patients to evaluate changes in limb positioning and gait associated with distal ulnar ostectomy.

Ex vivo preliminary investigation of radiographic quantitative assessment of cranial tibial displacement at varying degrees of canine stifle flexion with or without an intact cranial cruciate ligament.

BACKGROUND: The presence of cranial tibial subluxation can aid in the detection of joint instability as a result of CrCL injury. Detection of cranial tibial subluxation has been described using the tibial compression test (TCT) and cranial drawer test (CDT); however, diagnosis of CrCL insufficiency by assessing cranial subluxation motion of the tibia is subjective and difficult to quantify accurately. The aim of this study was to investigate a measurement technique to assess the degree of cranial tibial displacement relative to the femoral condyles on mediolateral projection stifle radiographs at varying degrees of stifle flexion (90°, 110°, and 135°) in CrCL intact, partially, and completely transected conditions. Radiographic measurements included: CrCL length and intercondylar distance (ICD), defined as the distance between the tibial mechanical axis (TMA) and the femoral condylar axis (FCA). The influence of CrCL status, stifle flexion angle, and measurement type on measured distance was evaluated. The relationship between CrCL length and ICD measurement was also assessed. RESULTS: Complete transection of the CrCL resulted in significant cranial tibial displacement. Stifle flexion angle affected ICD, but not CrCL length. Normalized measured CrCL length and ICD were significantly different; however, no differences existed between the change in distance detected by CrCL length and ICD measurements as CrCL transection status changed. Correlation coefficients detected a significant positive correlation between measured CrCL and ICD. CONCLUSION: The ICD measurement technique was able to quantify tibial displacement at various stifle flexion angles in the intact and completely transected CrCL conditions. The ICD measurement was more affected by stifle flexion angle than was the CrCL length.

Biomechanical evaluation of 6 transarticular tibiotarsal immobilization methods in canine cadaveric limbs.

OBJECTIVE: To determine the effects of 6 types of transarticular immobilization techniques on tibiotarsal joint angles during stimulated weight bearing. STUDY DESIGN: Canine ex vivo biomechanical study. SAMPLE POPULATION: Canine cadaveric pelvic limbs (n = 15). METHODS: A validation study was conducted to determine tibiotarsal flexion before and after transection of the superficial digital flexor tendon in 5 canine cadaveric limbs without tibiotarsal joint immobilization. Six transarticular tibiotarsal immobilization techniques were tested sequentially in 10 canine cadaveric pelvic limbs. The tibiotarsal joint angles were measured from lateral projection radiographs before and during axial loading of 200 N. Mixed linear models were applied to determine the effects of the immobilization techniques on change in tibiotarsal joint angle under loading. RESULTS: There was no change of tibiotarsal joint angle between extended digits and flexed digits under both unloaded and loaded conditions. Change in tibiotarsal joint angles did not differ among any of the immobilization techniques tested here (mean change 1.36°, range 0-5). The main contributor to variance in angle explained by the final model was associated with the random effect for limb. CONCLUSION: Changes in tibiotarsal joint angles during single static loading in canine cadaveric limbs for the 6 immobilization techniques were minimal. CLINICAL SIGNIFICANCE: The 6 techniques appear equally effective at limiting tibiotarsal joint flexion during single axial loading of 200 N. Cyclic mechanical testing of these techniques is recommended to support our findings and validate their clinical application.

Feasibility and safety of arthroscopic medial glenohumeral ligament and subscapularis tendon repair with knotless anchors: A cadaveric study in dogs.

OBJECTIVE: To test the feasibility and safety of an arthroscopic imbrication of the medial glenohumeral ligament (MGHL) and the subscapularis tendon with knotless anchors in dogs. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Ten limbs. METHODS: Cranial and caudal arms of the MGHL were imbricated with a 2.9- or a 2.4-mm knotless anchor. A horizontal mattress suture secured with a 3.5-mm knotless anchor was used to imbricate the subscapularis tendon. Computed tomography measurements included (1) the bone stock around the anchors, (2) the angle between the anchor and the joint surface (insertion angle), and (3) the angle formed by lines tangent to the cortices of the bones (safety angle). Limbs were dissected to assess the position of anchors. Safety and insertion angles and bone stock were compared among anchors with a Kruskal-Wallis test (P < .05). RESULTS: Surgical repairs were achieved in all limbs, with only 2 of 30 anchors incorrectly placed, both in the glenoid. The safety angle of the humeral anchor (HA; median, 89°) was greater than that of the cranial glenoid anchor (CrGA; P = .0017) and the caudal glenoid anchor (CdGA; P < .001). The insertion angle of the HA (median, 68°) was also greater than that of the other anchors (P < .001 and P = .001). The insertion angle of the CrGA (median, 26°) was greater (P = .0191) than that of the CdGA (median, 7°). All anchors were inserted at the MGHL and subscapularis footprint. CONCLUSION: Arthroscopic imbrication of MGHL and subscapularis tendon was feasible. HA were safer to place than glenoid anchors. CLINICAL SIGNIFICANCE: The results of this feasibility study justify further evaluation of the indications and outcomes of this technique in dogs with shoulder instability.

Second-look arthroscopic findings after CORA-based leveling osteotomy.

OBJECTIVE: To describe the arthroscopic appearance of intra-articular structures mid-term (9 months) and long-term (>12 months) after CORA-based leveling osteotomy (CBLO). STUDY DESIGN: Case series. ANIMALS: Dogs (n = 41) with second-look arthroscopy of the stifle after CBLO for treatment of a cranial cruciate ligament (CCL) deficiency. Both stifles were re-evaluated (stifles n = 42) in 1 dog. METHODS: Medical records of dogs that had second-look arthroscopy after CBLO were reviewed. Arthroscopic images of the femoral condyles were independently reviewed. The surgical report documented the integrity of menisci and articular cartilage of the tibial plateaus. RESULTS: The population included 7 stifles with stable partial CCL tears, 35 stifles with complete CCL tears (n = 28), or incompetent partial CCL tears (n = 7). Median time to second look arthroscopy was 16 months (9-24 months) for stable partial tears. The CCL remained intact in 6 stifles. The Outerbridge score of the articular cartilage of the femoral condyles was as 0 (6) or 1 (1). The articular cartilage of the tibial plateaus appeared normal in all stifles. Median time to second look arthroscopy of stifles with complete tears was 12 months (range, 9-34 months). The caudal cruciate ligament was normal or mildly fibrillated. The appearance of the articular cartilage of the femoral condyles was scored as 0 or near normal (grade 1-2) in all dogs. The articular cartilage of the tibial plateaus appeared normal, except in 1 dog with grade 4 lesion. CONCLUSION: CBLO results in minimal to no change in articular cartilage in at a median time of 14 months after surgery. Postoperative clinical lameness is often attributed to late onset meniscal pathology.

Provisional heritability estimates of four distraction index traits in a breeding population of German Shepherd dogs.

AIM To obtain provisional estimates of the heritability (h2 ) of passive laxity of the coxofemoral joints of a breeding colony of German Shepherd dogs, measured using the PennHIP distraction index (DI). METHODS Records were obtained of the PennHIP DI of right and left hips of 195 German Shepherd dogs (377 DI records) from the dog breeding colony of the New Zealand Police Dog Breeding Centre between 2003 and 2016, as well as pedigree records of 884 animals over four generations. Estimates of h2 and variance components for the log transformed DI data were obtained using restricted maximum likelihood procedures with a single trait sire model. Four DI traits for each dog were analysed: left hip, right hip, mean and worse-hip DI. The model included the fixed effects of sex and year of birth, with the age at scoring as a covariable, the random sire effect and residual error for each observation. RESULTS The h2 of the DI of the left hip (0.81, SE 0.40) was higher than the h2 of the DI of the right hip (0.35, SE 0.36). The h2 for the worse-hip DI (0.15, SE 0.28) in each dog was lower than the h2 of the individual hip DI, or the h2 for the mean of the two hips (0.53, SE 0.36) in each dog. The low number of generations prevented a meaningful analysis of the genetic trend. CONCLUSIONS AND CLINICAL RELEVANCE The h2 estimates for the left, right and mean DI traits were moderate to high, whereas the h2 estimates for the worse-hip DI (as used by the PennHIP programme for ranking of dogs) was low, but all estimates had large SE due to the small sample size. This provisional estimate of the h2 of four distraction index traits suggests that the mean DI could be useful as a selection tool against canine hip dysplasia in German Shepherd dogs, whereas the worse-hip DI may be less effective. Heritability estimates from a population with a greater number of DI measures is needed to validate this finding given the large SE in our study.

Radiographic indices for the diagnosis of atlantoaxial instability in toy breed dogs [corrected].

Toy breed dogs are overrepresented for atlantoaxial instability. Radiography is a standard diagnostic test, however published toy breed-specific radiographic measurements are lacking and diagnosis remains largely subjective. Aims of this retrospective, diagnostic accuracy study were to describe normal values and determine whether some quantitative radiographic criteria strongly support a diagnosis of atlantoaxial instability specific to toy breed dogs. Neutral lateral and ventrodorsal radiographs of 102 toy breed dogs (92 control, 10 affected) were reviewed. The median C1-C2 overlap (the distance of overlap between the C2 spinous process and the dorsal arch of C1) was +4.65 mm in control dogs and -5.00 mm in atlantoaxial instability cases. A C1-C2 overlap ≤ +1.55 mm was the most sensitive (100%) and specific (94.5%) radiographic measurement in the diagnosis of atlantoaxial instability. Three relative measurements were performed: the ventral atlantodental interval to dorsal atlantodental interval ratio, the dens/C2 ratio, and the C1-C2 angle. These three relative measurements had good specificity (94.5, 86.9, and 98.9%, respectively), lower sensitivity (80.0, 66.7, and 60.0%, respectively), and were not influenced by body weight (P > 0.05). Absolute measurements (including absolute dens length and atlantoaxial distance) were significantly correlated with body weight (P < 0.05) diminishing their utility in the diagnosis of atlantoaxial instability. Decreased C1-C2 overlap strongly supports atlantoaxial instability. The ventral atlantodental interval/dorsal atlantodental interval ratio, dens/C2 ratio, and C1-C2 angle may provide further support but may be normal in individual cases.