Digital analysis of ulnar trochlear notch sclerosis in Labrador retrievers

OBJECTIVES: To compare ulnar trochlear notch bone radiopacity in Labrador retrievers with and without fragmented medial coronoid process using quantitative analysis of film density on digitised radiographs. METHODS: Mediolateral view elbow radiographs from Labrador retrievers (n=34) aged between six and 18 months were obtained and digitised. Images from dogs with an arthroscopic diagnosis of fragmentation of the medial coronoid process (n=17) were compared with that of a control population (n=17), and this data subject to statistical analysis. RESULTS: A statistically significant relationship between the presence of increased trochlear notch radiopacity and a fragmented medial coronoid process was identified. Fractional analysis of this area shows the region of greatest difference in radiopacity between normal and fragmented medial coronoid process cohorts to be in the trochlear region of the medial coronoid process of the ulna. A decrease in radiopacity values in the dysplastic group versus the normal cohort was observed for the region of the proximo-caudal ulnar trochlear notch. CLINICAL SIGNIFICANCE: An increase in ulnar trochlear notch radiopacity is a finding associated with fragmentation of the medial coronoid process in Labrador retrievers.     

Reliability of radiological assessment of ulnar trochlear notch sclerosis in dysplastic canine elbows

Objectives : The objectives of this study were to quantify the sensitivity and specificity of visual assessment of radiographs of the canine elbow in detecting ulnar trochlear notch sclerosis, to establish interobserver and intra‐observer variation for the presence and grade of sclerosis and to quantify the effect of radiographic exposure on observer grading. Methods : Mediolateral elbow radiographs were obtained from Labrador retrievers (n=34) aged between six and 18 months. Radiographs from dogs with an arthroscopic diagnosis of fragmented medial coronoid process (n=17) and those from a control population (n=17) were subjected to observer grading for the presence or absence of and the grade of ulnar trochlear notch sclerosis. Interobserver and intra‐observer variation and observer sensitivity and specificity were calculated. Digital data from the ulnar trochlear notch were correlated with mean observer grade to quantify the effect of radiographic exposure on observer grade. Results : Interobserver agreement was “fair” (kappa=0·251 to 0·369) and intra‐observer agreement was “moderate” to “substantial” (kappa=0·462 to 0·667). The sensitivity of observer assessment was 72 per cent with a specificity of 22 per cent. Mean observer grade was not significantly correlated with the degree of radiographic exposure (P=0·70). Clinical Significance : Ulnar trochlear notch sclerosis is a phenomenon associated with fragmented medial coronoid process. However, interobserver agreement in grading this feature is only fair, being identified by observers with moderate sensitivity but with relatively poor specificity. This low specificity may predispose to overdiagnosis in clinical cases. Intra‐observer agreement is moderate to substantial, suggesting that individuals can reliably quantify this radiological feature on multiple occasions. The ability of observers to assess the degree of sclerotic change is not significantly affected by radiographic exposure.     

Demonstration of the articular cartilage of the canine ulnar trochlear notch using high-field magnetic resonance imaging

The articular cartilage covering the ulnar trochlear notch (UTN) of both elbow joints from 25 adult canine cadavers was demonstrated by the use of high-field magnetic resonance imaging (MRI) with a fat-suppressed, three-dimensional, spoiled gradient echo sequence. The dogs used for this study were divided into five groups: giant, large, mid-sized, small, and chondrodystrophic breeds. The distribution of articular cartilage of the UTN was assessed on MR images. The joints were then opened, and the distribution of the articular cartilage of the UTN was verified. In 29/50 joints, there was good agreement between gross findings of the distribution of the articular cartilage of the UTN and MRI interpretation. Reasons for the poor results in small and chondrodystrophic breeds were decreased thickness of the articular cartilage, small size of the articular surface and of its structural features, and the frequent inability to visualize the joint space.     

Comparison of the trotting gaits of Labrador Retrievers and Greyhounds

OBJECTIVE: To compare the trotting gaits of Labrador Retrievers and Greyhounds to determine whether differences in locomotion are attributable to differences in their manner of moving or to body size and shape differences between these 2 breeds. ANIMALS: 8 healthy 5-month-old Greyhounds and 5 healthy Labrador Retrievers between 6 and 18 months old. PROCEDURE: A series of 4 force platforms was used to record independent ground reaction forces on the forelimbs and hind limbs during trotting. Values of stride parameters were compared between breeds before and after normalization for size differences. Standard values of absolute and normalized stride period and stride length were determined from linear regressions of these parameters on relative (normalized) velocity. Forces were normalized to body weight and compared at the same relative velocity. RESULTS: Greyhounds used fewer, longer strides than the Labrador Retrievers to travel at the same absolute speed. After normalization for body size differences, most measurable differences between breeds were eliminated. Subtle differences that did persist related to proportion of the stride that the forefoot was in contact with the ground, timing of initial hind foot contact relative to initial forefoot contact, and distribution of vertical force between the forelimbs and hind limbs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that apparent differences in the trotting gait between Labrador Retrievers and Greyhounds are mainly attributable to differences in size, and that dogs of these 2 breeds move in a dynamically similar manner at the trot.     

Comparison of trochlear block recession and trochlear wedge recession for canine patellar luxation using a cadaver model

OBJECTIVE: To compare trochlear block recession (TBR) to trochlear wedge recession (TWR) with regards to patellar depth (percentage of patellar volume under the trochlear ridges), patellar articular contact, percentage of recessed trochlear surface area, and resistance to patellar luxation. STUDY DESIGN: In vitro computed tomography (CT) and biomechanical evaluation using a cadaver model. SAMPLE POPULATION: Twelve normal, large-breed canine cadavers. METHODS: Bilateral pelvic limb specimens with intact stifle joints were mounted on a positioning device. The femoral trochlear ridges were reduced to provide a standard shallow trochlea. TBR or TWR was performed to a standard depth randomly on paired specimens. CT and biomechanical evaluations were performed pre- and postoperatively in both an extended (148 degrees ) and flexed (113 degrees ) stifle position. CT images were digitized and measurements made using an image-analysis software program. Biomechanical testing consisted of applying 40 degrees of internal tibial rotation and documenting patellar luxation. RESULTS: The change in trochlear depth (depth of recession) was not significantly different between groups. In the extended stifle position (patella in the proximal trochlea), patellar depth and patellar articular contact with the recessed trochlea were significantly greater after TBR compared with TWR. The percentage of recessed trochlear surface area was significantly greater after TBR compared with TWR. In the extended position, a smaller percentage of the patellae luxated within 40 degrees of internal tibial rotation after TBR compared with TWR. CONCLUSIONS: TBR increases proximal patellar depth, increases patellar articular contact with the recessed proximal trochlea, recesses a larger percentage of trochlear surface area, and results in a greater resistance to patellar luxation in an extended position as compared with TWR. CLINICAL RELEVANCE: TBR may help limit the development of stifle DJD in dogs treated for canine patellar luxation.     

Abnormalities of the volar and plantar sesamoid bones in Rottweilers

The fore and hind feet of 50 unselected Rottweilers were examined clinically and radiographically for abnormalities of their volar and plantar sesamoid bones. Lesions were found in 22 (44 per cent), invariably affecting the No. 2 and/or No. 7 sesamoids. The majority occurred in the forelimb. Clinical signs were detected in only five dogs and local analgesia in these cases indicated that the sesamoid changes were not the cause of the presenting lameness. Radiographically the defect varied from small radiodense foci separated from an otherwise normal sesamoid, to gross distortion of the bone into a number of calcified bodies. In none of these dogs was the sesamoid abnormality demonstrated to cause lameness and it was not necessary, therefore, to treat the condition surgically. It is postulated that these lesions result from disordered ossification with subsequent degenerative changes.     

Characterization of the Biological Behavior of Appendicular Osteosarcoma in Rottweilers with a Comparison to Other Breeds

Introduction:  The clinical impression of many oncologists is that Rottweilers with appendicular osteosarcoma (OSA) have an unfavorable prognosis despite standard therapy (amputation and chemotherapy). The purpose of this study was to compare clinical characteristics, biological behavior and outcome of OSA in Rottweilers to that of other breeds.
Methods:  107 OSA cases were studied: 56 clinical cases (17 Rottweilers) and 54 necropsy submissions (13 Rottweilers) of OSA (3 cases overlapping). Information regarding signalment, prognostic factors, treatment and outcome was obtained from medical records and follow‐up with owners. Data were analyzed by chi‐square test, t‐test, and log rank test.
Preliminary Results:  Compared to other breeds Rottweilers were more likely to have femur (23% vs. 16%) and ulna (15% vs. 3%) and less likely to have tibia (8% vs. 27%) as their primary tumor location (p = 0.04). In the necropsy group, Rottweilers had a younger age at death (6.4 vs. 10 years, p = 0.0002) and a greater body weight at diagnosis (49 vs. 37 kg, p = 0.002). No statistical differences in the age at diagnosis or survival time were noted in Rottweilers vs. other breeds. Metastasis to lymph nodes (31% vs. 10%, p = 0.08) and lungs (64% vs. 49%, p = 0.24) was more frequent in Rottweilers. There was no difference in chemotherapy drugs given; however, Rottweilers were 20 times more likely to receive NSAIDs (p = 0.0004).
Conclusion:  Greater body weight with a predilection for certain tumor locations may contribute to OSA development in Rottweilers. A younger age at death may suggest a more aggressive phenotype.     

Fractures of the Calcaneus in Racing Greyhounds

Fifty-one calcaneus fractures associated with (41) or without (10) central tarsal bone (Tc) fractures in racing greyhounds were evaluated and categorized. All calcaneal fractures with no Tc fractures had a plantar proximal intertarsal subluxation. No subluxations were found in dogs with both calcaneal and central tarsal fractures. The calcaneal fractures were treated either with coaptation splints or surgical repair. Surgical techniques included a Steinmann pin with a figure eight tension band device or screw or plate fixation as primary techniques supplemented by Kirschner wires and cerclage wires. In all calcaneal fractures associated with plantar proximal intertarsal subluxation, an arthrodesis of the calcaneoquartal joint was performed. All 22 surgically repaired fractures in dogs available for physical and radiographic reexamination had healed within 1 to 6 months. Eight dogs with fractures of the calcaneus associated with fractures of Tc returned to a racing career. None of the dogs with plantar proximal intertarsal subluxation raced again. Based on the orientation of the fracture lines and on dissection of two tarsi with calcaneal fractures, a hypothesis on the pathogenesis of calcaneal fractures in racing greyhounds was formulated.     

Clinical pathology of Greyhounds and other sighthounds

Owing to the development of Greyhounds as racing sighthounds, these dogs have acquired unique physiologic adaptations that distinguish them from other breeds. Reference intervals for many analytes in retired racing Greyhounds (RRGs) differ from those of other breeds; most of the hematologic differences have also been described in other sighthounds. In this review, we provide a survey of the literature on clinical pathology of Greyhounds and other sighthounds and results of laboratory testing, including analysis of CBCs, biochemical profiles, coagulation tests, and blood gases, in RRGs at The Ohio State University. Major clinicopathologic differences in this breed include higher RBC mass, creatinine concentration, glomerular filtration rate, activities of hepatic enzymes, and concentration of cardiac troponin, as well as lower WBC, neutrophil, and platelet counts, thromboelastographic values, and concentrations of serum haptoglobin, total globulins, and T4.     

Ipsilateral vascularised ulnar transposition autograft for limb-sparing surgery of the distal radius in 2 dogs with osteosarcoma

Canine osteosarcoma is the most commonly diagnosed primary bone tumour in the dog, affecting mainly large and giant breed dogs with the predilection site being the metaphysis of long bones, specifically the distal radius, proximal humerus, distal femur and proximal tibia and fibula. Treatment options are either palliative or curative intent therapy, the latter limb amputation or limb-sparing surgery together with chemotherapy. This article describes the use of an ipsilateral vascularised ulnar transposition autograft as well as chemotherapy in 2 dogs with osteosarcoma of the distal radius. Both dogs showed minimal complications with the technique and both survived over 381 days following the surgery. Complications seen were loosening of the screws and osteomyelitis. The procedure was well tolerated with excellent limb use. This technique is indicated for use in cases with small tumour size that have not broken through the bone cortex.     

Calcification of the intervertebral discs and curvature of the radius and ulna: a radiographic survey of Finnish miniature dachshunds

The vertebral column of 124 randomly selected miniature dachshunds, representing 4.5% of the population registered by the Finnish Kennel Club during the years 1988 to 1996, were radiographed. The front legs were also radiographed in order to evaluate the curvature of the radius and ulna. Calcified discs were found in 75.9% of the longhaired miniature dachshunds and in 86.7% of the wirehaired ones. The occurrence of signs associated with IDD was 16.5% in longhaired and 15.6% in wirehaired miniature dachshunds. The occurrence of signs of IDD in dogs with calcified discs was 20.0% and 17.9% in longhaired and wirehaired miniature dachshunds, respectively. In dogs without calcifications only one dog showed signs of IDD. The curvature of the radius and the ulna did not differ between the dogs with signs of IDD and the healthy ones, or between the dogs with and without intervertebral calcifications. Our results indicate that radiographic eradication based on the presence of intervertebral calcifications is not suitable for breeding purposes for the Finnish miniature dachshund population because the percentage of dogs without calcifications is small.     

Anatomical and Radiological Studies of the Iliopubic Cartilage in Adult Greyhounds

The iliopubic cartilages of 70 greyhounds (30 males and 40 females) were studied in animals ranging in age from 18 months to 4 years. A combination of anatomic dissection and radiographie techniques was used to characterize the incidence of ossification or mineralization. An increase incidence of radiodense areas was demonstrated in female animals, but it was not statistically significant. The probable functional role of the iliopubic cartilage is discussed.     

Estimates of genetic parameters for hip and elbow dysplasia in Finnish Rottweilers

Data from 2,764 Rottweiler dogs born from 1987 to 1996 were analyzed with a Restricted Maximum Likelihood procedure using a mixed linear animal model to obtain variance component estimates for hip and elbow dysplasia. The data included 2,764 hip dysplasia and 2,278 elbow dysplasia records. Hip joints were scored as normal (0), borderline (1), slight (2), moderate (3), and severe (4, 4.5, and 5) hip dysplasia. Elbow joints were graded normal or borderline (0), slight (1), moderate (2), and severe (3) elbow dysplasia. The mean for the hip scores was 1.07 and for the elbow scores .60. Environmental effects influencing hip dysplasia were age, birth year, birth year x season interaction, and experience of the veterinarian responsible for x-raying the dog. For elbow dysplasia, statistically significant effects were age, birth year, sex of the dog, and panelist responsible for each screening. Estimates of heritability for hip and elbow dysplasia were .58 +/- .04 and .31 +/- .04, respectively, with a genetic correlation of .37 +/- .08 between the traits. Genetic improvement of almost one genetic standard deviation was observed in both traits during the 10 yr covered by the data.     

Induction of Anesthesia with Diazepam-Ketamine and Midazolam-Ketamine in Greyhounds

Anesthesia was induced in 14 greyhounds with a mixture of diazepam or midazolam (0.28 mg/kg) and ketamine (5.5 mg/kg), and maintained with halothane. There were no significant differences in weight, age, or duration of anesthesia between the treatment groups. Time to intubation with diazepam-ketamine (4.07 +/- 1.43 min) was significantly longer than with midazolam-ketamine (2.73 +/- 0.84 min). Heart rate, respiratory rate, PaCO2, and arterial pH did not vary significantly during anesthesia in either treatment group. Arterial blood pressures, PaO2, halothane vaporizer setting, and body temperature changed significantly from baseline values in both treatment groups during anesthesia. Times to sternal recumbency and times to standing were not significantly different. These data suggest that both diazepam-ketamine and midazolam-ketamine are useful anesthetic combinations in greyhounds. In combination with ketamine, midazolam offers little advantage over diazepam.     

Comparison of tibial plateau angle between clinically normal Greyhounds and Labrador Retrievers with and without rupture of the cranial cruciate ligament

OBJECTIVE: To compare tibial plateau angle (TPA) between Greyhounds without damage to the cranial cruciate ligaments and Labrador Retrievers with and without damage to the cranial cruciate ligaments. DESIGN: Clinical study. ANIMALS: 87 client-owned dogs and 15 research colony Greyhounds. PROCEDURE: Standing position, horizontal-beam radiography was performed on Greyhounds and unaffected Labrador Retrievers to determine standing TPA. Lateral radiography of the stifle joint was performed on all dogs to determine traditional TPA. Age and body weight were recorded for unaffected and affected Labrador Retrievers. RESULTS: Greyhounds had mean standing TPA of 1.56 degrees and mean traditional TPA of 22.50 degrees. Unaffected Labrador Retrievers had mean standing TPA of 3.52 degrees and traditional TPA of 27.97 degrees. Affected Labrador Retrievers had mean traditional TPA of 25.55 degrees. No significant difference was found in mean standing TPA between Greyhounds and unaffected Labrador Retrievers. Standing TPAs in Greyhounds and unaffected Labrador Retrievers were not significantly different from a plane drawn parallel to the ground. Significant differences in traditional TPAs were detected among all 3 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Greyhounds had mean traditional TPA of 22.50 degrees; similar angles should be considered normal for dogs. Although affected Labrador Retrievers had mean traditional TPA that was significantly greater than that of Greyhounds, the steepest TPA was found in unaffected Labrador Retrievers. Because Greyhounds and unaffected Labrador Retrievers had similar standing TPAs, we conclude that although TPA may be associated with damage to the cruciate ligaments, many dogs with a steep TPA do not develop cruciate ligament disease.     

Stress Fractures of the Acetabulum in 26 Racing Greyhounds

Acetabular fractures in 26 racing Greyhounds were reviewed. All fractures occurred during racing or training and were unrelated to any external trauma. All fractures had similar configurations, were minimally displaced, and involved only the acetabulum. Affected dogs were young (16-36 months). Fractures occurred unilaterally (22 dogs) and bilaterally (4 dogs). There was no sex predilection, and both right and left sides were equally represented. Bilateral fractures were associated with retraining between the occurrence of the first and second fractures. Radiographically, a fracture line was consistently visible in the caudal third of the acetabulum. Fractures in gross specimens resembled an inverted "Y." Results of histologic evaluation of two fractured acetabula showed changes characteristic of a nonunion fracture. Microfractures were evident in the grossly normal acetabulum opposite the fractured side. Evidence obtained from this study suggests a common pathogenesis of the fractures related to tremendous repetitive stresses produced during running. Greyhounds with unilateral acetabular fractures may provide a reproducible model for future studies of stress fractures in animals and humans because of the high incidence of bilateral fractures that develop during retraining. Surgical repair of the acetabular stress fracture was more successful than conservative management in returning the dogs to competitive racing.     

Distribution of power across the hind limb joints in Labrador Retrievers and Greyhounds

OBJECTIVE: To quantify angular excursions; net joint moments; and powers across the stifle, tarsal, and metatarsophalangeal (MTP) joints in Labrador Retrievers and Greyhounds and investigate differences in joint mechanics between these 2 breeds of dogs. ANIMALS: 12 clinically normal dogs (6 Greyhounds and 6 Labrador Retrievers) with no history of hind limb lameness. PROCEDURE: Small retroreflective markers were applied to the skin over the pelvic limb joints, and a 4-camera kinematic system captured data at 200 Hz in tandem with force platform data while the dogs trotted on a runway. Breed-specific morphometric data were combined with kinematic and force data in an inverse-dynamics solution for stance-phase net joint moments and powers at the stifle, tarsal, and MTP joints. RESULTS: There were gross differences in kinematic patterns between Greyhounds and Labradors. At the stifle and tarsal joints, moment and power patterns were similar in shape, but amplitudes were larger for the Greyhounds. The MTP joint was a net absorber of energy, and this was greater in the Greyhounds. Greyhounds had a positive phase across the stifle, tarsal, and MTP joints at the end of stance for an active push-off, whereas for the Labrador Retrievers, the only positive phase was across the tarsus, and this was small, compared with values for the Greyhounds. CONCLUSIONS AND CLINICAL RELEVANCE: Gross differences in pelvic limb mechanics are evident between Greyhounds and Labrador Retrievers. Joint kinetics in specific dogs should be compared against breed-specific patterns.