Treatment of Canine Appendicular Osteosarcoma Using Cobalt 60 Radiation and Intraarterial Cisplatin

Twelve dogs with appendicular osteosarcoma were treated with 24–40 Gy of cobalt 60 radiation and two doses of intraarterial cisplatin. Improvement in limb function occurred in four dogs, and three dogs, which had only mild initial lameness, had no worsening of their lameness post-treatment. In nine dogs in which local control was evaluable, eight had local failure, with the median (95% CI) duration of local control being 5.9 (4.6, 6.7) months. Two dogs had metastatic disease before therapy, and an additional nine dogs had metastatic disease at a median time of 6.4 months. Pathologic fracture was present in four dogs; two fractures occurred before treatment and two were documented at the time of tumor recurrence. Median (95% CI) survival time for all 12 dogs was 4.9 (3.4, 6.8) months. Excluding the two dogs with preexisting metastatic disease, median survival time was 6.7 months. Three dogs survived longer than 1 year. This mode of therapy was well tolerated and may be considered an alternative to amputation or limb-sparing surgical procedures in selected dogs with appendicular osteosarcoma.     

Results of Screw/Wire/Polymethylmethacrylate Composite Fixation for Acetabular Fracture Repair in 14 Dogs

Objective- To assess the clinical results in dogs with acetabular fractures stabilized using a screw-wire-polymethylmethacrylate (SWP) composite fixation.
Study Design- A retrospective study of client-owned dogs with acetabular fractures.
Animals- Fourteen dogs ranging in age from 4 to 95 months (mean, 34 ±25 months; median, 25 months) and body weight from 8 to 39 kg (mean, 25 ±6 kg; median, 27 kg).
Methods- Medical records and radiographs were retrospectively evaluated to determine location of the fracture, presence of preexisting degenerative joint disease, accuracy of fracture reduction and complications associated with surgery. Long-term results were evaluated by subjective assessment of lameness, elicitation of pain and/or crepitus on manipulation of the coxofemoral joint, measurements of pelvic limb circumference, coxofemoral joint goniometric measurements, and radiographic evaluation.
Results- Fracture reduction was considered anatomic in 13 dogs. At the time of the last follow-up evaluation (mean, 347 ±261 days; median, 380 days) 10 dogs were sound on the affected limb, three dogs had a subtle weight-bearing lameness of the affected limb, and the remaining dog had a consistent non-weight-bearing lameness of the affected limb. Mild (n = 10) or moderate (n = 1) degenerative changes of the affected coxofemoral joint attributed to the acetabular fracture and its repair were noted on the follow-up radiographs in 11 dogs. Limb circumference of the affected limb ranged from -8.2% to +10.8% (mean, -0.8 ±4.2%; median, -0.7%) of the contralateral limb.
Conclusions- The SWP composite fixation consistently maintained anatomic reduction, was associated with few complications, and yielded satisfactory clinical results.
Clinical Relevance- The SWP composite fixation technique would seem to be an acceptable means of stabilizing acetabular fractures in dogs.     

Amputation and Carboplatin for Treatment of Dogs With Osteosarcoma: 48 Cases (1991 to 1993)

Forty-eight dogs with histologically confirmed appendicular osteosarcoma (OSA) entered a prospective clinical trial evaluating treatment with amputation and up to 4 doses of carboplatin given every 21 days. The median disease-free interval (DFI) was 257 days, with 31.2% of the dogs disease-free at 1 year. The median survival time was 321 days, with 35.4% of the dogs alive at 1 year. Dogs with proximal humeral OSA had shorter DFI (P = .016) and survival (P = .037) times than dogs with OSA at other locations. Dogs with lower body weights (40 kg) had longer DFI (P = .0056) and survival (P = .007) times than larger dogs. Survival times for dogs that received carboplatin were statistically longer than those previously reported for amputation alone (P < .001). DFI and survival times are similar to those previously reported for 2 to 4 doses of cisplatin. Carboplatin appears to be a well-tolerated chemotherapeutic drug that can be given safely every 21 days at a dose of 300 mg/m². Neutropenia was the dose-limiting toxicity in this study. J Vet Intern Med 1996_;10:76–81. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Dental Composite for the Fixation of Mandibular Fractures and Luxations in 11 Cats and 6 Dogs

Twenty-one mandibular fractures in 11 cats and 6 dogs were repaired during a 20-month period. A new technique using dental composite was used to stabilize the mandible. The canine teeth were pumiced, acid etched, and aligned with dental composite, leaving the mouth opened approximately 1 cm. Six weeks after surgery the composite was removed so that radiographs of the mandible could be made with the animal under general anesthesia. In 1 dog in which the fracture had not healed, the composite was replaced. The composite broke before 6 weeks in 8 animals; 2 required replacement of the dental composite. There were no other complications. The median time for fracture healing was 6 weeks. All fractures healed with anatomic dental occlusion. The advantages of this technique are that no further damage is caused to the teeth or to the blood supply of the bone, the occlusion is anatomic, dermatitis (which is seen with tape muzzles) is not a complication, and the technique is easy to use in brachycephalic breeds, cats, and animals with poor bone quality. The limiting factor of this technique is that it does require four salvageable canine teeth. This repair technique is still a viable option even if one or more of the canine teeth are fractured. Dental composite stabilization is fast, easy, inexpensive, and, in our series, it was 100% effective for the repair of mandibular fractures.     

Dual-Energy X-Ray Absorptiometry and Force-Plate Analysis of Gait in Dogs With Healed Femora After Leg-Lengthening Plate Fixation

Dual-energy x-ray absorptiometry was used to measure bone mineral density of four regions in healed femora of nine dogs after fracture fixation with a leg-lengthening plate. Six to 85 months (mean, 46 months) after surgery, the bone mineral density of healed femora was not significantly different from the contralateral uninjured femora ( P >.05; power = 0.8 at Δ= 15%). Radio-lucencies around the proximal screws, apparently associated with screw loosening, were seen on radiographic views of the healed femora of three dogs. In one of these dogs, one screw in the proximal metaphysis had broken. Force-plate analysis of gait was also performed on dogs at the time of bone mineral density measurement. Peak vertical force was decreased in the pelvic limb with the healed fracture compared with the contralateral unoperated limb ( P < 0.05). Clinically apparent lameness in three dogs did not appear to be associated with altered bone mineral density and may have been caused by hip osteoarthritis, a nondisplaced hairline diaphyseal fracture, and screw loosening in conjunction with extensive post-traumatic soft tissue injury.     

Basal and Glucagon-Stimulated Plasma C-PeDtide Concentrations in Healthy Dogs, Dogs With Diabetes Millitus, and Dogs With Hyperadrenocorticism

Serum glucose and plasma C-peptide response to IV glucagon administration was evaluated in 24 healthy dogs, 12 dogs with untreated diabetes mellitus, 30 dogs with insulin-treated diabetes mellitus, and 8 dogs with naturally acquired hyperadrenocorticism. Serum insulin response also was evaluated in all dogs, except 20 insulin-treated diabetic dogs. Blood samples for serum glucose, serum insulin, and plasma C-peptide determinations were collected immediately before and 5,10,20,30, and (for healthy dogs) 60 minutes after IV administration of 1 mg glucagon per dog. In healthy dogs, the patterns of glucagon-stimulated changes in plasma C-peptide and serum insulin concentrations were identical, with single peaks in plasma C-peptide and serum insulin concentrations observed approximately 15 minutes after IV glucagon administration. Mean plasma C-peptide and serum insulin concentrations in untreated diabetic dogs, and mean plasma C-peptide concentration in insulin-treated diabetic dogs did not increase significantly after IV glucagon administration. The validity of serum insulin concentration results was questionable in 10 insulin-treated diabetic dogs, possibly because of anti-insulin antibody interference with the insulin radioimmunoassay. Plasma C-peptide and serum insulin concentrations were significantly increased (P < .001) at all blood sarnplkg times after glucagon administration in dogs with hyperadrenocorticism, compared with healthy dogs, and untreated and insulin-treated diabetic dogs. Five-minute C-peptide increment, C-peptide peak response, total C-peptide secretion, and, for untreated diabetic dogs, insulin peak response and total insulin secretion were significantly lower (P < .001) in diabetic dogs, compared with healthy dogs, whereas these same parameters were significantly increased (P < .011 in dogs with hyperadrenocorticism, compared with healthy dogs, and untreated and insulin-treated diabetic dogs. Although not statistically significant, there was a trend for higher plasma C-peptide concentrations in untreated diabetic dogs compared with insulin-treated diabetic dogs during the glucagon stimulation test. Baseline C-peptide concentrations also were significantly higher (P < .05) in diabetic dogs treated with insulin for less than 6 months, compared with diabetic dogs treated for longer than 1 year. Finally, 7 of 42 diabetic dogs had baseline plasma C-peptide concentrations greater than 2 SD (ie, >0.29 pmol/mL) above the normal mean plasma C-peptide concentration; values that were significantly higher, compared with results in healthy dogs (P < .001) and with the other 35 diabetic dogs (P < .001). In summary, measurement of plasma C-peptide concentration during glucagon stimulation testing allowed differentiation among healthy dogs, dogs with impaired β-cell function (ie, diabetes mellitusl, and dogs with increased β-cell responsiveness to glucagon (ie, insulin resistance). Plasma C-peptide concentrations during glucagon stimulation testing were variable in diabetic dogs and may represent dogs with type-1 and type-2 diabetes or, more likely, differences in severity of β-cell loss in dogs with type-1 diabetes. J Vet Intern Med 1996;10:116–122. Copyright © 1996 by the American College of Veterinary Internal Medicine.     

Spinal Fixation in Dogs Using Steinmann Pins and Methylmethacrylate

Steinmann pins and methylmethacrylate were used to stabilize 17 vertebral fractures or luxations and one unstable congenital spinal deformity in 18 dogs of a wide range of ages and body weights. Of 12 dogs available for follow-up examination (4–43 months), 10 were normal or only mildly ataxic, and two were ambulatory but severely ataxic. Five dogs died or were euthanized in the early postoperative period, but none of the deaths could be attributed to the technique. Uncommon complications associated with this fixation technique were pin migration and wound infection.     

A Biomechanical Comparison of Screw and Wire Fixation With and Without Polymethylmethacrylate Re-Enforcement for Acetabular Osteotomy Stabilization in Dogs

Objective— Compare the biomechanical characteristics of screw and wire fixation with and without polymethylmethacrylate (PMMA) re-enforcement for acetabular osteotomy stabilization in dogs. Animals— Pelves removed from 8 adult mixed breed dogs weighing between 25 and 30 kg. Procedure— The pubic symphysis of each pelvis was split and a central transverse acetabular osteotomy was performed. One hemipelvis from each dog was stabilized with the composite fixation (interfragmentary Kirschner wire, two screws and a figure-of-eight orthopedic wire with PMMA). The contralateral hemipelves was stabilized with an interfragmentary Kirschner wire, two screws, and a figure-of-eight orthopedic wire without PMMA. All hemipelves were tested in bending by using a materials testing machine at a cross head speed of 5 mm/min. An extensometer was placed on the dorsomedial surface of the hemipelves centered over acetabular osteotomy to record distraction of the osteotomy during loading. A load/deformation curve and a load/distraction curve was produced for each hemipelvis. The slope for the initial linear portion of the load/deformation curve and the load/distraction curve, yield load and maximum load sustained were compared between repair groups using a paired t-test with P < .05 considered significant. Results— The slope of the load/deformation curve was significantly greater (P= .001 ) for hemipelves stabilized with the composite fixation (mean ± SD: 69 ± 18 N/mm) compared with hemipelves stabilized without PMMA (mean ± SD: 39 ± 8 N/mm). There was no significant difference (P= .593 ) between repair groups in the slope of the load/distraction curves as measured on the extensometer. Yield load was significantly greater (P= .0002 ) for hemipelves stabilized with the composite fixation (mean ± SD: 184 ± 25 N) compared to hemipelves stabilized without PMMA (mean ± SD: 74 ± 12 N). Maximum load sustained was also significantly greater (P= .013 ) for hemipelves stabilized with the composite fixation (mean ± SD: 396 ± 71 N) compared to hemipelves stabilized without PMMA (mean ± SD: 265 ± 94 N). Failure of hemipelves stabilized with the composite fixation occurred primarily by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site. Failure of hemipelves stabilized without PMMA occurred by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site with pronounced concurrent ventrolateral rotation of the cranial pelvic segment. Conclusion— PMMA improves the mechanical characteristics of acetabular fracture fixation, at least in part by neutralization of rotational forces. The results of this study justify use of PMMA as a component of the composite fixation when repairing acetabular fractures.     

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.     

Plasma Taurine Concentrations in Normal Dogs and in Dogs With Heart Disease

Plasma taurine concentrations were determined in 76 dogs with dilated cardiomyopathy (DCM), 28 dogs with acquired valvular disease (AVD), and 47 normal (control) dogs. The data were collected at 2 referral centers. The Animal Medical Center, New York, NY (AMC), and the University of California, Davis (UCD), and the studies were conducted independently. Different anticoagulants (sodium citrate at AMC and lithium heparin at UCD) were used to collect the plasma samples. Paired analysis of samples showed a significant difference in plasma taurine concentrations, depending on the anticoagulant used. Consequently, results from each clinic were analyzed separately. Plasma taurine concentrations were significantly higher in dogs with AVD (median, 133 nmol/mL; range, 25 to 229 nmol/mL) than in control dogs (median, 63 nmol/mL; range 44 to 224 nmol/mL) and dogs with DCM (median, 72 nmol/mL; range, 1 to 247 nmol/mL) at AMC (P= .001). The number of dogs with AVD at UCD was too small to draw meaningful conclusions. At UCD, the median plasma taurine concentration was 98 nmol/mL (range, 28–169 nmol/mL) in dogs with AVD, 75 nmol/mL (range, 0.1–184 nmol/mL) in dogs with DCM, and 88 nmol/mL (range 52–180 nmol/mL) in control dogs. There were no significant differences in plasma taurine concentrations between dogs with DCM and the control dogs at either hospital. Congestive heart failure and administration of cardiac medication had no significant effect on plasma taurine concentrations. Plasma taurine concentration was low (<25 nmol/mL) in 17% (13/76) of the dogs with DCM. Seven of the 13 dogs with low plasma taurine concentrations were Cocker Spaniels or Golden Retrievers. It was concluded that most dogs with DCM do not have low plasma taurine concentrations. However, certain breeds or individual dogs may have low plasma taurine concentrations in association with DCM. Whether this association is causal or not is unknown. The significance of the high plasma taurine concentrations in dogs with AVD is also unknown.