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- Author or Editor: Stewart D. Ryan x
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Abstract
OBJECTIVE
To compare the bursting strength of the uterine horns (UHs) and cervical-vestibule junction (CVJs) of rabbits following sealing with a vessel-sealing device (VSD) or encircling ligatures.
SAMPLE
UHs and CVJs collected from 30 rabbit (Oryctolagus cuniculus) cadavers.
PROCEDURES
UHs and CVJs were randomly assigned to sealing with encircling Miller knot ligatures (LIG; n = 10 CVJs and 20 UHs) or a VSD (12 CVJs and 24 UHs). Lumens were infused with saline (0.9% NaCl) solution under pressure until seals burst or to a maximum pressure of 300 mm Hg.
RESULTS
For CVJs, median (range) bursting pressure of the LIG and VSD groups was > 300 mm Hg (224 to > 300 mm Hg) and 35 mm Hg (0 to 60 mm Hg), respectively. Five of 12 CVJs in the VSD group failed at pressures < 33 mm Hg. For UHs, median (range) bursting pressure of the LIG and VSD groups was 255 mm Hg (120 to > 300 mm Hg) and 154 mm Hg (range, 44 to 202 mm Hg), respectively.
CONCLUSIONS AND CLINICAL RELEVANCE
The evaluated VSD was effective in sealing UHs at bursting pressures well in excess of expected physiologic pressures, indicating that the VSD may be useful for ovariectomy procedures in rabbits. However, CVJ seals created with the VSD were ineffective and could potentially burst at low pressures, which could predispose to urine entering the abdomen. Given these results, we do not recommend sealing of the CVJ with a VSD for ovariohysterectomy in rabbits.
Abstract
Objective—To evaluate the mechanical properties of canine carpal ligaments for use in a finite element model of the canine antebrachium.
Sample Population—26 forelimbs obtained from cadavers of 13 dogs euthanized for reasons unrelated to this study.
Procedures—6 ligaments (medial collateral, lateral collateral, palmar ulnocarpal, palmar radiocarpal, accessorometacarpal-V, and accessorometacarpal-IV) were evaluated. Quasistatic tensile tests were performed on all specimens (n = 8 specimens/ligament) by use of a servohydraulic materials testing system in conjunction with a 6-df load cell. Each specimen was preconditioned for 10 cycles by applying 2% strain by use of a Haversine waveform. Tension was subsequently applied to each specimen at a strain rate of 0.5%/s until ligament failure.
Results—Significant differences in modulus of elasticity were detected among the ligaments. Elastic modulus did not differ significantly between the 2 accessorometacapal ligaments, between the 2 collateral ligaments, or between the 2 palmar carpal ligaments. Ligaments were classified into 3 groups (accessorometacarpal ligaments, intra-articular ligaments, and palmar carpal ligaments), and significant differences were detected among the 3 ligament groups. The accessorometacarpal ligaments had a relatively high elastic modulus, compared with results for the other ligaments. The medial and lateral collateral ligaments had the lowest elastic modulus of any of the ligaments tested.
Conclusions and Clinical Relevance—These results indicated a strong function-elastic modulus relationship for the 6 ligaments tested. The mechanical properties described here will be of use in creating a finite element model of the canine antebrachium.
Abstract
OBJECTIVE To assess for any association between a history of tibial plateau leveling osteotomy (TPLO) and subsequent development of proximal tibial osteosarcoma in dogs.
DESIGN Matched case-control study.
ANIMALS 34 client-owned dogs in which proximal tibial osteosarcoma was diagnosed between January 2005 and December 2012 (cases) and 79 dogs without osteosarcoma, matched 3:1 to cases (when possible) by age, breed, and initial examination date (controls).
PROCEDURES Information on each case and control was collected from the medical records and other sources regarding date of birth, sex and neuter status, body weight, breed, and whether TPLO had been performed ≥ 1 year ago. A multivariable conditional logistic regression model was constructed to evaluate associations of body weight and history of TPLO with the outcome of proximal tibial osteosarcoma in dogs.
RESULTS After adjusting for body weight in the multivariable model, dogs with a history of TPLO were 40 times as likely to develop proximal tibial osteosarcoma as were dogs with no history of TPLO. In addition, each 1-kg (2.2-lb) increase in body weight was associated with an 11% increase in the odds of proximal tibial osteosarcoma.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that dogs with a history of TPLO were at increased risk of developing osteosarcoma of the proximal region of the tibia relative to dogs with no such history. Therefore, it is important for proximal tibial osteosarcoma to be included among the differential diagnoses for new or worsening hind limb lameness in dogs that underwent TPLO ≥ 1 year previously.
Abstract
Objective—To develop an orthotopic model of canine osteosarcoma in athymic rats as a model for evaluating the effects of stereotactic radiotherapy (SRT) on osteosarcoma cells.
Animals—26 athymic nude rats.
Procedures—3 experiments were performed. In the first 2 experiments, rats were injected with 1 × 106 Abrams canine osteosarcoma cells into the proximal aspect of the tibia (n = 12) or distal aspect of the femur (6). Tumor engraftment and progression were monitored weekly via radiography, luciferase imaging, and measurement of urine pyridinoline concentration for 5 weeks and histologic evaluation after euthanasia. In the third experiment, 8 rats underwent canine osteosarcoma cell injection into the distal aspect of the femur and SRT was administered to the affected area in three 12-Gy fractions delivered on consecutive days (total radiation dose, 36 Gy). Percentage tumor necrosis and urinary pyridinoline concentrations were used to assess local tumor control. The short-term effect of SRT on skin was also evaluated.
Results—Tumors developed in 10 of 12 tibial sites and all 14 femoral sites. Administration of SRT to rats with femoral osteosarcoma was feasible and successful. Mean tumor necrosis of 95% was achieved histologically, and minimal adverse skin effects were observed.
Conclusions and Clinical Relevance—The orthotopic model of canine osteosarcoma in rats developed in this study was suitable for evaluating the effects of local tumor control and can be used in future studies to evaluate optimization of SRT duration, dose, and fractionation schemes. The model could also allow evaluation of other treatments in combination with SRT, such as chemotherapy or bisphosphonate, radioprotectant, or parathyroid hormone treatment.
Abstract
Objective—To determine the signalment, tibial plateau leveling osteotomy (TPLO) plate type, clinical staging information, treatment, and oncological outcome in dogs that developed osteosarcoma at the proximal aspect of the tibia following TPLO and to calculate the interval between TPLO and osteosarcoma diagnosis.
Design—Multi-institutional retrospective case series.
Animals—29 dogs.
Procedures—Medical records from 8 participating institutions were searched for dogs that developed osteosarcoma (confirmed through cytologic or histologic evaluation) at previous TPLO sites. Signalment, TPLO details, staging tests, treatment data, and outcome information were recorded. Descriptive statistics were calculated, and disease-free intervals and survival times were evaluated by means of Kaplan-Meier analysis.
Results—29 dogs met the inclusion criteria. The mean age was 9.2 years and mean weight was 45.1 kg (99.2 lb) at the time of osteosarcoma diagnosis. Most dogs had swelling over the proximal aspect of the tibia (17/21) and lameness of the affected limb (28/29). The mean interval between TPLO and osteosarcoma diagnosis was 5.3 years. One type of cast stainless steel TPLO plate was used in most (18) dogs; the remaining dogs had received plates of wrought stainless steel (n = 4) or unrecorded type (7). Twenty-three of 29 dogs underwent treatment for osteosarcoma. Median survival time for 10 dogs that underwent amputation of the affected limb and received ≥ 1 chemotherapeutic treatment was 313 days.
Conclusions and Clinical Relevance—Results supported that osteosarcoma should be a differential diagnosis for dogs with a history of TPLO that later develop lameness and swelling at the previous surgical site. Oncological outcome following amputation and chemotherapy appeared to be similar to outcomes previously reported for dogs with appendicular osteosarcoma.
