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- Author or Editor: David A. Hawkins x
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Abstract
Objective—To quantify the passive contribution of the biceps brachii muscle-tendon unit to the limits of elbow joint extension during shoulder joint flexion in horses.
Sample Population—Normal right forelimb specimens from 6 Thoroughbred cadavers.
Procedure—Specimens included the scapula, humerus, radius-ulna, biceps brachii muscle-tendon unit, and stabilizers of the shoulder and elbow joints. Specimens were mounted to a rigid board by transfixation pins through the humerus and instrumented for mechanical manipulation of the limb and joint angle and load measurements. Flexion and extension limits of shoulder and elbow joint ranges of motion were measured in each joint separately, while the other joint was fixed. Measurements were made before and after transection of the biceps brachii muscle- tendon unit.
Results—The biceps brachii muscle-tendon unit limited elbow joint extension when the shoulder joint was fixed in flexion, limited shoulder joint flexion when the elbow joint was fixed in extension, and inhibited shoulder joint extension to a lesser degree when the elbow joint was fixed at midrange angles of 75° to 90°.
Conclusions and Clinical Relevance—Clinical manipulation of the elbow joint into hyperextension during shoulder joint flexion is indicative of biceps brachii injury. (Am J Vet Res 2005;66:391–400)
Abstract
Objective—To determine the relative contributions of the muscles, tendons, and accessory ligaments to the passive force-length properties of the superficial (SDF) and deep digital flexor (DDF) myotendinous complexes.
Sample Population—8 cadaveric forelimbs from 6 adult Thoroughbreds.
Procedure—In vitro, limb configurations during slack position and myotendinous lengths during subsequent axial loading of forelimbs were recorded before and after transection of accessory ligaments. Expressions were derived to describe the forcelength behavior of each muscle, tendon, and accessory ligament-tendon unit; linear stiffness was computed for these components. The elastic modulus was established for the SDF and DDF tendons.
Results—Linear stiffness was 2.80 ± 0.38 kN/cm for the SDF muscle, 3.47 ± 0.66 kN/cm for the DDF muscle, 2.73 ± 0.18 kN/cm for the SDF tendon, 3.22 ± 0.20 kN/cm for the DDF tendon, 6.46 ± 0.85 kN/cm for the SDF accessory ligament, 1.93 ± 0.11 kN/cm for the SDF accessory ligament-tendon unit, and 2.47 ± 0.11 kN/cm for the DDF accessory ligament-tendon unit. The elastic modulus for the SDF and DDF tendons was 920 ± 77 and 843 ± 56 MPa, respectively.
Conclusions and Clinical Relevance—Both the muscle-tendon and ligament-tendon portions of SDF and DDF myotendinous complexes had important roles in supporting the forelimb of horses. Although muscle tension can be enhanced by elbow joint flexion and active contraction, the accessory ligaments transmitted more force to the distal tendons than did the muscles under the conditions tested. (Am J Vet Res 2004;65:188–197)
Abstract
Objective—To investigate the biomechanics of cervical vertebral motion units (VMUs) before and after a ventral slot procedure and after subsequent pin-polymethylmethacrylate (pin-PMMA) fixation and to assess the use of smooth and positive-profile threaded (PPT) pins in pin-PMMA fixation and intravertebral pin placement.
Sample Population—Cervical portions (C3 through C6 vertebrae) of 14 cadaveric canine vertebral columns.
Procedure—Flexion and extension bending moments were applied to specimens before and after creation of a ventral slot across the C4-C5 intervertebral space and after subsequent smooth or PPT pin-PMMA fixation at that site. Data for the C3-C4, C4-C5, and C5-C6 VMUs were compared among treatments and between pin types, and pin protrusion was compared between pin types.
Results—Compared with values in intact specimens, ventral slot treatment increased neutral zone range of motion (NZ-ROM) by 98% at the treated VMUs and appeared to decrease overall ROM at adjacent VMUs; pin-PMMA fixation decreased NZ-ROM by 92% at the treated VMUs and increased overall NZ-ROM by 19% to 24% at adjacent VMUs. Specimens fixed with PPT pins were 82% (flexion) and 80% (extension) stiffer than smooth–pin-fixed specimens. Overall, 41% of pins protruded into foramina; PPT pins were more likely to protrude into transverse foramina.
Conclusions and Clinical Relevance—Results indicated that fixation of a cervical VMU alters the biomechanics of adjacent VMUs and may contribute to degeneration of adjacent intervertebral disks. Use of threaded pins may lower the incidence of pin loosening and implant failure but enhances the likelihood of transverse foramina penetration. ( Am J Vet Res 2005;66:678–687)
Abstract
Objective—To evaluate the effects of 4.7-mg deslorelin acetate implants on egg production and plasma concentrations of 17β-estradiol and androstenedione in Japanese quail (Coturnix coturnix japonica) over 180 days and assess safety of the implants in quail via gross and histologic examination.
Animals—20 female Japanese quail.
Procedures—Following a 7-day period of consistent egg laying, quail were anesthetized and received a 4.7-mg deslorelin implant (treatment group; n = 10) or identical placebo implant (control group; 10) SC between the scapulae. Egg production was monitored daily. Plasma concentrations of 17β-estradiol and androstenedione were measured on days 0 (immediately prior to implant injection), 14, 29, 62, 90, 120, 150, and 180 via radioimmunoassay. Birds were weighed periodically and euthanized at day 180 for complete necropsy.
Results—Egg production was significantly decreased in the treatment group, compared with the control group, from 2 to 12 weeks after implant injection. Egg production ceased in 6 of 10 quail in the treatment group (mean duration of cessation, 70 days). Plasma androstenedione and 17β-estradiol concentrations were significantly lower on day 29 in the treatment group than in the control group. Plama androstenedione and 17β-estradiol concentrations were significantly lower on day 29 in the treatment group then in the control group.
Conclusions and Clinical Relevance—4.7-mg deslorelin acetate implants reversibly decreased egg laying for approximately 70 days in most of the Japanese quail evaluated. Further studies evaluating implants containing different concentrations of the drug are needed in quail and other avian species.
Abstract
CASE DESCRIPTION
An 8-year-old sexually intact female eclectus parrot (Eclectus roratus) with a 4-day history of hyporexia and lethargy and a 1-day history of tenesmus was examined.
CLINICAL FINDINGS
Severe leukocytosis characterized by severe heterophilia and moderate monocytosis was present. Marked dilation of the proventriculus and ventriculus and ascites were identified by means of radiography, coelomic ultrasonography, and contrast-enhanced CT, with no clinically relevant motility noted on ultrasonography. Results of coelomic fluid analysis were consistent with pyogranulomatous effusion. Endoscopy of the upper gastrointestinal tract following proventricular and ventricular lavage showed a thick caseous plaque occupying 30% of the caudal proventricular mucosa. Abundant yeast organisms were evident during cytologic examination of a proventricular and ventricular wash sample, and fecal culture yielded Candida glabrata.
TREATMENT AND OUTCOME
The bird was treated with SC fluids, assisted feedings, nystatin, fluconazole, amoxicillin–clavulanic acid, enrofloxacin, gastroprotectants, maropitant, and analgesics and slowly improved during hospitalization. A marked decrease in proventricular dilation was evident on serial radiographs obtained over a 12-month period. One year after diagnosis, the bird was presented with a 1-week history of hyporexia and lethargy, and fecal culture grew C glabrata. Antifungal treatment was resumed for 3 months. The bird had no clinical signs of infection 16 months after this recurrence, and subsequent fecal cultures were negative for fungal growth.
CLINICAL RELEVANCE
Findings illustrate the importance of upper gastrointestinal endoscopy in diagnosing proventricular and ventricular dilation in birds and emphasize the need for long-term antifungal treatment and monitoring in birds with fungal infections.
Abstract
CASE DESCRIPTION
A 4-year-old spayed female mixed-breed rabbit was evaluated because of a 3-year history of sneezing and nasal discharge that were refractory to medical management.
CLINICAL FINDINGS
Signs of chronic left-sided rhinitis and sinusitis were observed on physical examination and confirmed by CT evaluation. Lysis of the rostral aspect of the left maxillary bone and destruction of nasal turbinates were evident on CT images.
TREATMENT AND OUTCOME
Pararhinotomy of the left maxillary sinus through the facies cribrosa was performed. Purulent material was removed from the maxillary sinus recesses, a middle meatal antrostomy was completed to allow permanent drainage into the left middle nasal meatus, and the tissues were closed routinely. Microbial culture of a sample from the maxillary sinus recesses revealed Bordetella bronchiseptica, undetermined fastidious nonenteric bacteria, and Streptococcus viridans. Medical management was continued, and nasal discharge resolved but sneezing persisted. Increased sneezing and bilateral nasal discharge developed 1.5 years later; CT examination revealed right-sided rhinitis, and culture of a nasal swab sample revealed Bordetella spp, Staphylococcus spp, and Micrococcus spp. Right-sided pararhinotomy and middle meatal antrostomy were performed, and medical management continued. A subsequent recurrence was managed without additional surgery; 4 years after the initial surgery, the rabbit was still receiving medical treatment, with mild intermittent nasal discharge and sneezing reported.
CLINICAL RELEVANCE
This report describes a surgical approach for treatment of chronic rhinitis in companion rabbits with maxillary sinus involvement that included creation of a permanent drainage pathway from the maxillary sinus to the middle nasal meatus.
Abstract
OBJECTIVE To determine the pharmacokinetics and adverse effects following SC administration of ceftiofur crystalline free acid (CCFA) in New Zealand White rabbits.
ANIMALS 6 adult sexually intact female New Zealand White rabbits.
PROCEDURES Each rabbit was administered 40 mg of CCFA/kg SC. A blood sample was obtained immediately before (0 minutes), at 5 and 30 minutes after, and at 1, 1.5, 2, 3, 4, 8, 12, 24, 48, 72, 95, 120, 144, and 168 hours after administration, and plasma concentrations of ceftiofur free acid equivalents (CFAE) were measured. Pharmacokinetic parameters were calculated. For each rabbit, body weight, food consumption, fecal output, and injection site were monitored. Minimum inhibitory concentrations of ceftiofur for 293 bacterial isolates from rabbit clinical samples were determined.
RESULTS Mean ± SD peak plasma concentration of CFAE and time to maximum plasma concentration were 33.13 ± 10.15 μg/mL and 1.75 ± 0.42 hours, respectively. The mean terminal half-life of CFAE was 42.6 ± 5.2 hours. Plasma CFAE concentration was > 4 μg/mL for approximately 24 hours and > 1 μg/mL for at least 72 hours after CCFA administration. An apparently nonpainful subcutaneous nodule developed at the injection site in 3 of 6 rabbits.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that CCFA (40 mg/kg) could be administered SC every 24 to 72 hours to New Zealand White rabbits to treat infections with ceftiofur-susceptible bacteria. Single-dose administration of CCFA resulted in minimal adverse effects. Additional studies are needed to evaluate the effects of repeated CCFA administration in New Zealand White rabbits.
Abstract
Objective—To calculate the prevalence of urolithiasis in client-owned chelonians examined at a veterinary teaching hospital and to describe the clinical signs, diagnosis, and treatment of urolithiasis in chelonians.
Design—Retrospective case series.
Animals—40 client-owned turtles and tortoises with urolithiasis.
Procedures—The medical record database of a veterinary teaching hospital was searched from 1987 through 2012 for records of client-owned chelonians with urolithiasis. The prevalence of urolithiasis was calculated for client-owned chelonians examined at the hospital. Signalment and physical examination, hematologic, biochemical, urinalysis, diagnostic imaging, treatment, and necropsy results were described.
Results—The mean prevalence of urolithiasis in client-owned chelonians for the study period was 5.1 cases/100 client-owned chelonians examined. Thirty-one of the 40 chelonians were desert tortoises. Only 5 of 40 chelonians had physical examination abnormalities associated with the urogenital tract. Surgery was performed on 17 chelonians; 5 developed postoperative complications, and 4 of those died. Necropsy was performed on 18 chelonians, and urolithiasis contributed to the decision to euthanize or was the cause of death for 9. Uroliths from 13 chelonians were analyzed, and all were composed of 100% urate.
Conclusions and Clinical Relevance—Results indicated chelonians with urolithiasis have various clinical signs and physical examination findings that may or may not be associated with the urinary tract. Hematologic, biochemical, and urinalysis findings were nonspecific for diagnosis of urolithiasis. Many chelonians died or were euthanized as a consequence of urolithiasis, which suggested the disease should be identified early and appropriately treated.
Abstract
Objective—To calculate normative joint angle, intersegmental forces, moment of force, and mechanical power at elbow, antebrachiocarpal, and metacarpophalangeal joints of dogs at a walk.
Animals—6 clinically normal mixed-breed dogs.
Procedure—Kinetic data were collected via a force platform, and kinematic data were collected from forelimbs by use of 3-dimensional videography. Length, location of the center of mass, total mass, and mass moment of inertia about the center of mass were determined for each of 4 segments of the forelimb. Kinematic data and inertial properties were combined with vertical and craniocaudal ground reaction forces to calculate sagittal plane forces and moments across joints of interest throughout stance phase. Mechanical power was calculated as the product of net joint moment and the angular velocity. Joint angles were calculated directly from kinematic data.
Results—All joint intersegmental forces were similar to ground reaction forces, with a decrease in magnitude the more proximal the location of each joint. Flexor moments were observed at metacarpophalangeal and antebrachiocarpal joints, and extensor moments were observed at elbow and shoulder joints, which provided a net extensor support moment for the forelimb. Typical profiles of work existed for each joint.
Conclusions and Clinical Relevance—For clinically normal dogs of a similar size at a walk, inverse dynamic calculation of intersegmental forces, moments of force, and mechanical power for forelimb joints yielded values of consistent patterns and magnitudes. These values may be used for comparison in evaluations of gait in other studies and in treatment of dogs with forelimb musculoskeletal disease. (Am J Vet Res 2003;64:609–617)
Abstract
Objective—To evaluate clinical findings, complications, and outcome of horses and foals with third metacarpal, third metatarsal, or phalangeal fractures that were treated with transfixation casting.
Design—Retrospective case series.
Animals—29 adult horses and 8 foals with fractures of the third metacarpal or metatarsal bone or the proximal or middle phalanx.
Procedures—Medical records were reviewed, and follow-up information was obtained. Data were analyzed by use of logistic regression models for survival, fracture healing, return to intended use, pin loosening, pin hole lysis, and complications associated with pins.
Results—In 27 of 35 (77%) horses, the fracture healed and the horse survived, including 10 of 15 third metacarpal or metatarsal bone fractures, 11 of 12 proximal phalanx fractures, and 6 of 8 middle phalanx fractures. Four adult horses sustained a fracture through a pin hole. One horse sustained a pathologic unicortical fracture secondary to a pin hole infec-tion. Increasing body weight, fracture involving 2 joints, nondiaphyseal fracture location, and increasing duration until radiographic union were associated with horses not returning to their intended use. After adjusting for body weight, pin loosening was associated with di-aphyseal pin location, pin hole lysis was associated with number of days with a transfixation cast, and pin complications were associated with hand insertion of pins.
Conclusions and Clinical Relevance—Results indicated that transfixation casting can be successful in managing fractures distal to the carpus or tarsus in horses. This technique is most suitable for comminuted fractures of the proximal phalanx but can be used for third metacarpal, third metatarsal, or middle phalanx fractures, with or without internal fixation.
