Lumbar paraspinal muscle transverse area and symmetry in dogs with and without degenerative lumbosacral stenosis.

OBJECTIVES: To investigate whether dogs with degenerative lumbosacral stenosis have decreased lumbar paraspinal muscle transverse area and symmetry compared with control dogs. MATERIALS AND METHODS: Retrospective cross-sectional study comparing muscles in transverse T2-weighted magnetic resonance images for nine dogs with and nine dogs without degenerative -lumbosacral stenosis. Mean transverse area was measured for the lumbar multifidus and sacrocaudalis dorsalis lateralis muscles bilaterally and the L7 vertebral body at the level of the caudal endplate. Transverse areas of both muscle groups relative to L7 and asymmetry indices were compared between study populations using independent t tests. RESULTS: Mean muscle-to-L7 transverse area ratios were significantly smaller in the degenerative lumbosacral stenosis group compared with those in the control group in both lumbar multifidus (0·84 ±0·26 versus 1·09 ±0·25; P=0·027) and sacrocaudalis dorsalis lateralis (0·5 ±0·15 versus 0·68 ±0·12; P=0·005) muscles. Mean asymmetry indices were higher for both muscles in the group with degenerative lumbosacral stenosis than in the control group, but highly variable and the difference was not statistically significant. CLINICAL SIGNIFICANCE: These findings suggest that dogs with degenerative lumbosacral stenosis have decreased lumbar paraspinal muscle mass that may be a cause or consequence of the -syndrome. Understanding altered paraspinal muscle characteristics may improve understanding of the -pathophysiology and management options for degenerative lumbosacral stenosis.

Kinetic and kinematic evaluation of compensatory movements of the head, pelvis and thoracolumbar spine associated with asymmetric weight bearing of the pelvic limbs in trotting dogs.

OBJECTIVES: To determine ground reaction forces, head and pelvis vertical motion (HVM and PVM, respectively), and thoraco-lumbar lateral angular motion (LAM) of the spine using kinematic gait analysis in dogs with mild asymmetric weight-bearing of the pelvic limbs while trotting. METHODS: Twenty-seven hound-type dogs were fitted with reflective markers placed on the sagittal crest of the skull, the ischiatic tuberosity, and thoracolumbar spine of dogs to track motion while trotting. Kinetic and kinematic data were used to characterize asymmetry between the left and right pelvic limbs, and to describe HVM, PVM and thoraco-lumbar LAM. Maximum and minimum position and total motion values were determined for each measured variable. RESULTS: Dogs with asymmetric weight bearing of the pelvic limbs had greater PVM on the side with a greater peak vertical force (PVF), and greater thoraco-lumbar LAM toward the side with a lower PVF while trotting. No differences in mean HVM were detected, and there were no significant correlations between the magnitude of HVM, PVM and thoraco-lumbar LAM and the degree of asymmetric weight bearing. CLINICAL SIGNIFICANCE: Dogs with subtle asymmetric weight bearing of a pelvic limb had patterns of body motion that may be useful in identifying subtle lameness in dogs; greater PVM on the side with greater weight bearing and greater thoraco-lumbar LAM toward the side with less weight bearing while trotting. Description of these compensatory movements is valuable when evaluating dogs with subtle weight bearing asymmetry in the pelvic limbs and may improve the sensitivity of lameness detection during subjective clinical lameness examination.

Exercises in canine physical rehabilitation: range of motion of the forelimb during stair and ramp ascent.

OBJECTIVES: To evaluate overall joint range of motion of the forelimb in healthy dogs ascending stairs compared with incline slope walking. METHODS: Normal canine forelimb kinematics (range of motion, flexion and extension) were compared during ascent of stairs or a ramp, and compared to unimpeded trotting on a flat surface. Eight adult dogs with no evidence of orthopaedic or neurological lameness were assessed using a 2-dimensional kinematic system as they walked up a custom built ramp and stairs. RESULTS: In healthy dogs, ramp and stair ascent consistently had greater range of motion compared to trotting on a flat surface, and ramp ascent had significantly greater range of motion compared to stair ascent (P<0·05). Shoulder flexion and extension, elbow extension and carpal flexion were all significantly greater while ascending the ramp compared to stairs. Shoulder extension on the flat was significantly greater than while ascending stairs. CLINICAL SIGNIFICANCE: When planning physical rehabilitation exercises following injury to the forelimb, stair and ramp ascent may be considered, as both augment range of motion of joints. Ramp ascent provides the greatest increase in range of motion of forelimb joints.

The use of cyclosporine-A in dogs with chronic osteoarthritis: a pilot study.

OBJECTIVE: To evaluate the efficacy of cyclosporine-A in dogs with radiographic and physical evidence of chronic stifle osteoarthritis. MATERIALS AND METHODS: Ten hound-type dogs with osteoarthritis induced by surgical transection of a cranial cruciate ligament followed by immediate stabilization of the stifle four years prior to study start were randomized to two groups. Cyclosporine-A was administered orally once daily at 5 mg/kg to one group for one month while the other group served as control. After a two week wash-out period during which the animals were not treated, and the degree of lameness was allowed to return to baseline, the treatments were switched so that the second group received treatment with cyclosporine-A and the first group served as control. Ground reaction forces were measured using a force platform in all animals at day zero and then every two weeks until the end of the study. RESULTS: Cyclosporine-A did not alter the degree of lameness based on assessment of ground reaction forces. CONCLUSIONS: At a dose of 5 mg/kg/day for 28 days, cyclosporine-A was not effective in decreasing lameness of dogs with chronic osteoarthritis induced by surgical transection of the cranial cruciate ligament.

Kinematics of stair ascent in healthy dogs.

OBJECTIVE: The purpose of the study was to evaluate the kinematic characteristics of pelvic limb joints in orthopaedically normal dogs during stair ascent. DESIGN: Prospective study. PROCEDURE: Eight hound-type dogs were fitted with reflective spheres at palpable landmarks, including the tuber ischium, greater trochanter, cranial dorsal iliac spine, lateral epicondyle of the femur, lateral malleolus, and the base of the fifth metatarsal bone. Each dog was walked up a set of custom made stairs consisting of four steps and then trotted across a level test space. Data were recorded for the right and left pelvic limbs during ascent. Maximum and minimum joint angles and total joint motion were calculated for all joints and evaluated statistically. RESULTS: Pelvic limb joints had a greater total joint excursion during stair ascent. There was greater extension of the coxofemoral and tibiotarsal joints during ascent, whereas the stifle joint had less extension. Maximum flexion of the stifle and tarsal joints was significantly greater in stair ascent. There was not any significant difference between the right and left limbs. CONCLUSIONS: All joints of the pelvic limb undergo a greater joint motion to ascend stairs.

Kinematic analysis of the pelvic limbs of healthy dogs during stair and decline slope walking.

OBJECTIVES: To evaluate range of motion (ROM) of the pelvic limb in healthy dogs descending stairs compared with decline slope walking. METHODS: Reflective spheres were placed on the skin over the joints of the right pelvic limb of seven adult, hound-type dogs with no clinical signs of orthopaedic or neurologic disease. Five trials of stair and ramp descent of each dog were recorded using four 60 Hz digital infrared cameras. Two-dimensional kinematic data were collected as dogs walked down stairs and on a continuous decline of equivalent slope. Maximum and minimum joint angles and ROM were calculated for the coxofemoral, femorotibial and tibiotarsal joints. RESULTS: Stair descent resulted in significantly greater femorotibial flexion and tibiotarsal flexion and extension compared with continuous slope descent. Significantly greater ROM was achieved in the coxofemoral, femorotibial and tibiotarsal joints during stair descent. CLINICAL SIGNIFICANCE: Compared with a continuous slope, stair descent achieves greater ROM in the pelvic limbs of dogs. Stair descent may be a useful therapeutic exercise to improve ROM in dogs with musculoskeletal disease of the pelvic limb, and ramp descent may be easier for dogs with limited motion of pelvic limb joints.

Effects of 3.3-MHz ultrasound on caudal thigh muscle temperature in dogs.

OBJECTIVE: To examine the tissue-temperature changes that occur at various depths during 3.3-MHz ultrasound (US) treatments of the caudal thigh muscles in dogs. STUDY DESIGN: A prospective, randomized, experimental study. ANIMALS: Ten mixed-breed research dogs. METHODS: Two US treatments, one at an intensity of 1.0 W/cm(2) and one at 1.5 W/cm2, were administered to the caudal thigh region of 10 adult male and female hound-type dogs weighing 20.5 to 25.0 kg. Needle thermistors were inserted in the caudal thigh muscles below the skin surface at depths of 1.0, 2.0, and 3.0 cm, directly under the US treatment area. Both intensities of US treatment were performed on each dog over a 10-cm2 area for 10 minutes using a sound head with an effective radiating area of 5 cm2. Treatments were administered in random order. Tissue temperature was measured before, during, and after US treatment until tissue temperature returned to baseline. RESULTS: At the completion of the 10-minute US treatment, the temperature rise at an intensity of 1.0 W/cm2 was 3.0 degrees C at the 1.0-cm depth, 2.3 degrees C at 2.0-cm depth, and 1.6 degrees C at 3.0-cm depth. At an intensity of 1.5 W/cm2, temperatures rose 4.6 degrees C at the 1.0-cm depth, 3.6 degrees C at 2.0-cm depth, and 2.4 degrees C at 3.0-cm depth. Tissue temperatures returned to baseline within 10 minutes or sooner after treatment in all dogs. CONCLUSIONS: This study demonstrates that significant heating occurs in the superficial thigh muscle of dogs during 3.3-MHz US. CLINICAL RELEVANCE: 3.3-MHz US can be used to increase superficial tissue temperature in dogs, although the amount of time that tissue temperature remains elevated is relatively short.

Bone- and non-bone-derived growth factors and effects on bone healing.

In the future, it may be possible to manipulate the fracture site with exogenous growth factors to allow successful union of the bone ends without additional surgery. The complex interaction of growth factors, the timing of their appearance and disappearance at the wound site, and the concentrations necessary to achieve specific effects must be studied more thoroughly. For growth factors to find widespread clinical use, there must be evidence that healing is enhanced. It may be difficult to enhance the healing of fresh fractures in normal animals, and it may also be difficult to demonstrate the healing of nonunion fractures. Because of the great variability in fractures of clinical patients, studies designed to determine the effect of growth factors on bone healing must be carefully designed with appropriate attention given to randomizing patients based on the risk of delayed healing and other patient characteristics.

Radiographic, densitometric, and biomechanical effects of recombinant canine somatotropin in an unstable ostectomy gap model of bone healing in dogs.

OBJECTIVE: To determine the effect of recombinant canine somatotropin (STH) on radiographic, densitometric, and biomechanical aspects of bone healing using an unstable ostectomy gap model. STUDY DESIGN: After an ostectomy of the midshaft radius, bone healing was evaluated over an 8-week period in control dogs (n = 4) and dogs receiving recombinant canine STH (n = 4). ANIMALS OR SAMPLE POPULATION: Eight sexually intact female Beagle dogs, 4 to 5 years old. METHODS: Bone healing was evaluated by qualitative and quantitative evaluation of serial radiographs every 2 weeks. Terminal dual-energy x-ray absorptiometry and three-point bending biomechanical testing were also performed. RESULTS: Dogs receiving STH had more advanced radiographic healing of ostectomy sites. Bone area, bone mineral content, and bone density were two to five times greater at the ostectomy sites of treated dogs. Ultimate load at failure and stiffness were three and five times greater in dogs receiving STH. CONCLUSIONS: Using the ostectomy gap model, recombinant canine STH enhanced the radiographic, densitometric, and biomechanical aspects of bone healing in dogs. CLINICAL RELEVANCE: Dogs at risk for delayed healing of fractures may benefit from treatment with recombinant canine STH.

Determination of proximal femoral epiphyseal depth for repair of physeal fractures in immature dogs.

OBJECTIVE: To determine the depth that implants may be safely placed for repair of proximal femoral physeal fractures. STUDY DESIGN: Relationships were determined between the depth of the proximal femoral epiphysis (PFE) and the contralateral PFE, and the PFE and pubic bone width. ANIMALS OR SAMPLE POPULATION: 20 immature dog cadavers. METHODS: Actual PFE depths were determined at the center of the physeal surface and at four other eccentric points. The contralateral intact PFE depth and the width of the cranial aspect of the public bone were measured from radiographs. RESULTS: Mean ratios of actual central PFE depth to radiographically measured (1) contralateral PFE depth and (2) pubic bone width were 1.04:1, and 1.09:1, and ratios of actual eccentric PFE depths were 0.89:1 and 0.93:1. Body weight was not useful in estimating depth of the PFE. CONCLUSIONS: For the central epiphysis, pins may safely be placed a distance equal to 75% to 80% of the contralateral intact PFE depth or pubic bone width, measured from a ventrodorsal radiograph, with minimal risk of penetration through the articular surface. Pins placed eccentrically may be safely driven a depth equal to 65% of the radiographically measured contralateral intact PFE depth or pubic bone width. CLINICAL RELEVANCE: Estimating the safe depth of implant placement into the PFE avoids penetration of the articular surface.

Determination of safe depth of pin penetration for repair of distal femoral physeal fractures in immature dogs: a comparison of normograde and retrograde pin placement.

OBJECTIVE: The purpose of this study was to determine the depth that implants may be safely placed into the distal femoral epiphysis (DFE) for the repair of distal femoral physeal fractures. STUDY DESIGN: The depth of the DFE was related to the radiographic thickness of the patella in this experimental study. ANIMALS OR SAMPLE POPULATION: Twenty immature canine cadavers. METHODS: Patella thicknesses were measured from lateral radiographs. Actual DFE depths were determined for pins driven in normograde fashion and for pins driven retrograde from the central depression between the metaphyseal pegs and from the cranial pegs. The association of DFE depth and patella thickness was evaluated using linear regression analysis. Using 95% confidence intervals, rules for estimating the safe depth of implant placement into the DFE were determined. RESULTS: DFE depth had significant correlation with patella thickness for pins placed in retrograde fashion from the central depression between the metaphyseal pegs (r2 = .83) and from the cranial pegs (r2 = .82) and for pins placed in normograde fashion (r2 = .65). CONCLUSIONS: Based on 95% confidence intervals, pins placed in retrograde fashion from the central depression between the metaphyseal pegs may be safely driven into the DFE a distance equal to 140% of patella thickness. Pins placed from the cranial metaphyseal pegs may be driven to a depth equal to 80% of patella thickness, and pins placed in normograde fashion may be driven to a depth equal to 30% of patella thickness. CLINICAL RELEVANCE: Measurement of patella thickness assists the surgeon in determining the approximate depth that pins may be driven into the DFE without penetrating the articular surface of the stifle joint.

Scapular fractures in dogs: epidemiology, classification, and concurrent injuries in 105 cases (1988-1994).

A retrospective study of canine scapular fractures diagnosed and treated from 1988 through 1994 at four veterinary teaching hospitals was performed. Dogs (n = 105) with 109 scapular fractures were included. Most scapular fractures occurred in young (i.e., less than four years of age), male, medium- to large-breed (i.e., greater than 10 kg) dogs as the result of vehicular trauma. Concurrent injuries (primarily thoracic trauma) occurred in approximately 70% of cases. In-house follow-up evaluations were considered adequate in only 17% of the cases. A classification system that includes biomechanical principles for categorization is described to avoid discrepancies between various traditional classification systems.

Pericardiectomy in dogs: 22 cases (1978-1994).

OBJECTIVE: To determine long-term outcome of dogs with neoplastic and nonneoplastic pericardial disease that undergo pericardiectomy. DESIGN: Retrospective study. ANIMALS: 22 dogs. PROCEDURE: Dogs that underwent pericardiectomy and in which the diagnosis had been confirmed histologically were included. Data collected from each record included signalment, history, clinical signs, results of diagnostic evaluations, operative management, postoperative complications, histologic diagnosis, and outcome. Dogs were grouped on the basis of underlying cause of pericardial disease (neoplastic vs nonneoplastic), and survival times were determined by means of Kaplan-Meier analyses. RESULTS: 9 dogs had neoplastic pericardial disease (chemodectoma, 4; hemangiosarcoma, 2; malignant mesothelioma, 2; lymphoblastic lymphoma, 1). Thirteen dogs had nonneoplastic pericardial disease (benign idiopathic pericarditis, 10; lymphocytic plasmacytic pericarditis, 2; osseous metaplasia of unknown cause, 1). Thoracic radiography and echocardiography were the most specific methods for diagnosis of pericardial effusion. Pleural effusion was the most common postoperative complication (8/22 dogs). Prevalence of postoperative complications was not associated with underlying cause of pericardial disease, surgical approach, or surgical procedure (subtotal vs total pericardiectomy). Median survival time of dogs with neoplastic disease (52 days) was significantly shorter than median survival time of dogs with nonneoplastic disease (792 days). Dogs that developed pleural effusion > 30 days after pericardiectomy had a poor prognosis for survival. CLINICAL IMPLICATIONS: Radiography and echocardiography are useful for diagnosis of pericardial effusion in dogs. Dogs with neoplastic pericardial disease have a significantly shorter survival time than do dogs with nonneoplastic pericardial disease.

The role of exercise and physical modalities in the treatment of osteoarthritis.

Physical rehabilitation is a valuable and often underutilized part of the overall management of small animals with OA. A team consisting of the veterinarian, physical therapist, veterinary technician, and owner is vital to determine and carry out an appropriate therapeutic regimen. To maintain enthusiasm for the program, measurements should be regularly obtained to document progress. In addition, controlled studies should be performed to determine the degree of improvement that may be expected with physical rehabilitation programs.

Metabolic and histologic effects of recombinant canine somatotropin on bone healing in dogs, using an unstable ostectomy gap model.

OBJECTIVE: To investigate the effect of recombinant canine somatotropin (STH) on the metabolic and histologic aspects of bone healing in dogs, using an unstable ostectomy gap model. ANIMALS: 8 mature dogs. PROCEDURE: A 3-mm ostectomy of the mid portion of the radius was performed in all dogs. Implants designed to release STH at a rate of 4 mg/d were placed SC in 4 dogs (treated group [STHG]), and another 4 dogs received no implants (control group [CG]). Serum concentrations of STH, insulin-like growth factor I, and osteocalcin were determined before surgery, and weekly for 8 weeks. Scintigraphic evaluation of the ostectomy sites was performed before surgery, and at weeks 2, 4, 6, and 8 after surgery. Histologic evaluation ofthe ostectomy sites was performed at the conclusion of the study at week 8. RESULTS: Significant (P < 0.05) increases in serum STH, insulin-like growth factor I, and osteocalcin concentrations were observed in dogs of the STHG during the 8-week study period. Scintigraphic activity of the ostectomy sites was increased in dogs of both groups, but dogs of the STHG had significantly (P < 0.05) greater activity, compared with dogs of the CG. Coalescence of nuclear activity across the ostectomy site was observed in dogs of the STHG, whereas dogs of the CG maintained 2 distinct areas of metabolic activity. Histologically, dogs of the STHG had bridging calluses with areas of endochondral ossification and ongoing osteogenic activity, whereas dogs of the CG had nonossified fibrocartilage typical of nonunion fractures. CONCLUSION: Using the ostectomy gap model, recombinant canine STH enhanced the metabolic and histologic aspects of bone healing in dogs.

Comparison of coagulation test results for blood samples obtained by means of direct venipuncture and through a jugular vein catheter in clinically normal dogs.

OBJECTIVE: To determine whether coagulation test results for blood samples obtained from heparinized jugular vein catheters in dogs are accurate. DESIGN: Prospective, controlled study. ANIMALS: Fourteen clinically normal dogs. PROCEDURE: Prothrombin time, activated partial thromboplastin time, concentration of fibrin degradation products, and fibrinogen concentration were measured in blood samples obtained by means of direct jugular venipuncture and through an indwelling jugular vein catheter 0, 2, 8, 24, and 48 hours after catheter placement. Blood samples were collected from the catheter by means of a 2-syringe technique, which involved discarding the first volume of blood collected. RESULTS: For all sample times, mean values for samples obtained from the jugular vein catheter were not significantly different from mean values for samples obtained by means of venipuncture. CLINICAL IMPLICATIONS: Blood samples for coagulation tests may be obtained from jugular vein catheters up to 48 hours after catheter placement in clinically normal dogs.

Gastric dilatation-volvulus after splenic torsion in two dogs.

Two dogs developed gastric dilatation-volvulus 2 and 17 months, respectively, after splenectomy for treatment of splenic torsion. Splenic displacement and torsion may stretch the gastric ligaments, allowing increased mobility of the stomach. After splenectomy, an anatomic void may be created in the cranioventral part of the abdomen, contributing to the mobility of the stomach. Veterinarians treating dogs with isolated splenic torsion may wish to consider prophylactic gastropexy at splenectomy, to reduce the chance of future gastric dilatation-volvulus. Prophylactic gastropexy should be done only if the dog's hemodynamic status is stable enough to allow for performance of the additional surgery.

Biomechanical comparison of 1-screw and 2-divergent pin internal fixations for treatment of slipped capital femoral epiphysis, using specimens obtained from immature dogs.

Biomechanical strength and stiffness of 2 fixation treatments used to repair acute slipped capital femoral epiphysis were evaluated in bone specimens form immature dogs. A servohydraulic testing machine was used to create slipped capital femoral epiphysis in 7 pairs of femurs by shearing the capital femoral epiphysis along the physis in a craniocaudal direction. The slip was reduced and repaired with one 3.5-mm-diameter screw placed in lag fashion or 2 double-pointed, 1.6-mm (0.062 inch)-diameter smooth pins and retested. Strength and stiffness of each intact femur (which served as the control) and repaired femur were compared. Results of the study indicated that the failure strength of 2-pin fixation was significantly (P < 0.05) weaker than its control and the 1-screw fixation. There was no significant difference between failure strength of the 1-screw fixation and its control. The stiffness of 1-screw and 2-pin fixations was not significantly different, compared with each other, but was significantly (P < 0.05) less, compared with their respective controls.

Abnormal hemostatic profiles and gastric necrosis in canine gastric dilatation-volvulus.

Hemostatic profiles (prothrombin time, activated partial thromboplastin time, fibrinogen concentration, fibrin degradation product concentration, platelet count, and antithrombin III activity) were acquired prospectively in 20 dogs with a diagnosis of gastric dilatation-volvulus. Eighteen dogs had abnormal results of one or more hemostatic test, including eight dogs that had hemostatic profiles consistent with a diagnosis of disseminated intravascular coagulation. During surgery, or at necropsy, the dogs' stomachs were evaluated for gross abnormalities, and lesions were graded subjectively as mild, moderate, or severe. Eight dogs had mild gastric lesions, five had moderate lesions, and seven had severe changes indicating gastric necrosis. Seventy percent (7/10) of the dogs with two to six abnormal hemostatic test results had gastric necrosis, whereas none of the 10 dogs with no or one abnormality had gastric necrosis (p < .001). A multiple linear regression equation, based on fibrin degradation product concentration, activated partial thromboplastin time, and antithrombin III activity was derived to predict gastric necrosis. This equation correctly identified gastric necrosis with 86% sensitivity, 100% specificity, 100% positive predictive value, and 93% negative predictive value.

Biomechanical comparison of three internal fixations for treatment of slipped capital femoral epiphysis in immature dogs.

The biomechanical strength and stiffness of 3 fixation techniques used to repair acute slipped capital femoral epiphysis were evaluated in bone specimens from immature dogs. A servohydraulic testing machine was used to create slipped capital femoral epiphysis in 9 pairs of femurs by shearing the capital femoral epiphysis along the physis in a craniocaudal direction. The slip was reduced and repaired with 1, 2, or 3 double-pointed, 1.6-mm (0.062-inch) smooth pin(s) and retested. The strength and stiffness of each intact femur (which served as the control) and repaired femur were compared. Results of the study indicated that differences among the failure strengths of 1- and 2-pin fixations and their respective controls were not significant; however, the 3-pin fixation was 29% stronger than its control and was 60 and 45% stronger than the 1- and 2-pin fixations, respectively. One- and 2-pin fixations were 34 and 24% less stiff than their respective controls, whereas the stiffness of the 3-pin fixation was similar to its control. The 2- and 3-pin fixations were 48 and 76% stiffer, respectively, than the 1-pin fixation, but were not significantly different, compared with each other.