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The use of a polyglycolide lactide cement plug restrictor in cemented femoral fixation during total hip arthroplasty was evaluated. Femoral cement pressurization was evaluated in vitro in a cadaveric model and the host response to polymer degradation was evaluated in vivo in a canine total hip arthroplasty model. Sixteen embalmed anatomic specimen femurs were prepared for cement femoral fixation. The intramedullary canal was plugged with either an ultrahigh molecular weight polyethylene cement plug restrictor or a polyglycolide lactide cement plug restrictor. Peak pressures in the proximal, mid, and distal portions of the cement mantle were recorded during cement insertion, cement pressurization, and implant insertion. There was no difference between the two plug groups in peak pressures throughout the cement mantle during cement insertion, pressurization, or implant insertion. Total hip arthroplasty using a cementless acetabular component and a cemented femoral stem was performed in 24 dogs. The femoral intramedullary canal was plugged with a polyethylene or a biodegradable cement plug restrictor. The dogs were sacrificed at 7 weeks, 10 months, or 15 months. Radiographically, no osteolytic lesions were seen around either plug type. Histomorphometrically, the polyglycolide lactide plugs appeared intact at 7 weeks and partially degraded by 10 and 15 months. In both plug groups, a mild fibrohistiocytic reaction with infiltration of fibrocytes, histocytes, and endothelial cells was seen. No osteolysis was observed. The results of the current study show that femoral cement pressurization can be attained in vitro using a biodegradable cement plug restrictor and that for as long as 15 months in the in vivo canine model there were no adverse reactions associated with use of these plugs compared with conventional ultrahigh molecular weight polyethylene plugs.

SummaryThe purpose of this study was to evaluate the use of three dimensional imaging techniques in veterinary orthopaedic surgery to measure hip congruity and predict changes in congruity resulting from triple pelvic osteotomies of canine hips. Preoperative, postoperative, and post-simulation measurements of congruity were obtained from eight canine hips by determination of Norberg angles from ventrodorsal pelvic radiographs (1), and lateral centre-edge (CE) angles from three dimensional (3 D) reconstructions of computed tomography (CT) scan data (2). Half of the hips were treated with a triple pelvic osteotomy with 30 degrees of axial rotation, and the other half served as approached but unoperated controls. Each measurement was performed three times by a single evaluator blinded to the identity of each hip. Lateral centre-edge angle measurements were more precise than Norberg angle measurements as determined by the calculated measurement of reliability (R = 0.78 and 0.68 respectively). Triple pelvic osteotomy resulted in an increase in congruity (as measured by lateral CE angles) of 52.2 ± 4.6 degrees compared to -3.0 ± 6.3 degrees in the control hips. The medical imaging programme used to perform the 3D reconstructions from CT scan data also allowed manipulation of the resulting preoperative 3D images to simulate on the computer screen the triple pelvic osteotomies performed on the gross specimens. Surgical procedure simulation predicted the change in congruity (as measured by lateral CE angles) of operated hips to be 43.5 ± 8.8 degrees. The images obtained by 3D reconstruction were very sensitive indicators of gross hip morphology. Visualization of structures, superimposed or surrounded by bone, was easily performed on the computer by interactive manipulation of the three dimensional CT scan reconstructions. In addition to its unique imaging capabilities, this technique appears to be a useful method for non-invasive measurement and prediction of the effects of triple pelvic osteotomy on hip congruity in dogs.Three dimensional (3D) computer aided image reconstructions were performed on tomographic scan data collected from dysplastic canine pelves before and after triple pelvic osteotomy (TPO). Descriptions of imaging capabilities and the application of lateral centre-edge angles for the determination of hip congruity are reported. Simulations performed on the computer accurately predicted the changes in congruity achieved by surgery.

An important need in hemodialysis is a self-sealing prosthesis for vascular access with at least equivalent patency and biostability to expanded polytetrafluoroethylene (ePTFE) alternatives. The authors have developed a Corethane/polyester composite (CPC) graft with an inner blood interfacing layer of spun Corethane fibers (10-15 microns diameter; pore size 30-60 microns) impregnated with a gelatin-heparin complex and an outer soft tissue interfacing warp-knitted polyester sheath. Twenty-six CPC grafts (6 mm internal diameter; 25-30 cm length) and eight Gore-Tex ePTFE grafts (same dimensions) were implanted as femoral artery-to-vein shunts in dogs on low dose (162 mg/day) aspirin, and subjected to weekly dialysis needle punctures for up to 52 weeks. Patency was 73% (19/26 with 15 at 52 weeks) for the CPC grafts and 63% (5/8 at 52 weeks) for the ePTFE controls, with more favorable healing (e.g., less extensive mural thrombi) of the CPC grafts. The hemostasis time per needle pair after removal (3.1 min mean for CPC versus 21.2 min mean for ePTFE) and the blood loss in achieving hemostasis (5.7 g mean for CPC versus 47.9 g for ePTFE) documented the significant (p < 0.0001) performance advantages of the CPC prosthesis.

Therapeutic renal transplantation in dogs is currently being investigated as a treatment for endstage renal disease. This pilot study examines the effect of donor bone marrow (DBM) infusion and antithymocyte serum (ATS) in combination with immunosuppressive drug therapy in prolonging renal allograft survival in dogs. Seven normal outbred mongrel dogs received an unmatched renal allograft. All dogs received rabbit anti-dog thymocyte serum (RADTS), prednisone (Pr), cyclosporine-A (CsA) and azathioprine (Aza). In addition, three dogs (group 1 test) received DBM and four dogs (group 2 control) did not receive DBM. Serum CsA levels were measured throughout the study. Immunosuppressive therapy was gradually reduced with Pr, CsA, and Aza withdrawn at 200, 450, and 680 days, respectively. Allograft rejection was treated with prednisolone sodium succinate. One dog in group 1 and one in group 2 died as a result of infectious canine rhinotracheitis and rejection early in the study. Renal allograft torsion occurred in one group 1 dog. The remaining four dogs survived the 2 years of the study. The dogs in group 2 (three dogs) all rejected the renal allograft after total drug withdrawal, the surviving dog in group 1 did not. This study demonstrates that RADTS, Pr, CsA, and Aza in combination can prolong renal allograft survival in mongrel dogs, whereas DBM may enhance the unresponsive state.

The occurrence of primary endotracheal adenocarcinoma in two 12-year-old cats is reported. Dyspnoea was the most dominant clinical sign in both cases. The endotracheal masses were identified radiographically and removed via thoracotomy and tracheotomy in the first case and cervical tracheal resection and anastomosis in the second case. In both cases, the diagnosis of adenocarcinoma was confirmed histopathologically.

SummaryTo reduce postoperative complications due to pelvic canal narrowing following triple pelvic osteotomy, it is important to minimize the length of the pubic remnant on the acetabular segment. Three different techniques for performing the pubic osteotomy were compared: a lateral wire saw technique, a lateral osteotome technique and a ventral osteotome ostectomy technique. The lateral wire saw and ventral ostectomy techniques resulted in significantly shorter pubic remnants than the lateral osteotome technique. The osteotomies performed with the wire saw were more accurate and precise than those performed with the osteotome. The lateral wire saw technique is a practical alternative to the ventral ostectomy technique for performing the pubic osteotomy.A comparison of three different pubic osteotomy techniques for the triple pelvic osteotomy showed that minimal pubic remnants can be achieved with either the lateral wire saw or ventral ostectomy technique. Osteotomies made by the wire saw were more accurate and precise than those made by the osteotome.

We have developed a composite vascular prosthesis with the inner blood interfacing layer made of a porous elastomeric membrane of spun Corethane fibers (10-15 microns in diameter, pore size 30-60 microns) impregnated with a gelatin-heparin complex and an outer soft tissue interfacing warp knitted Dacron sheath. Forty-eight Corethane/Dacron composite (CDC) vascular grafts, 4 mm in diameter and 5 cm in length, and 48 expanded polytetrafluoroethylene (ePTFE) vascular grafts of similar size were implanted bilaterally as end to end interposition grafts on opposite sides in the carotid and femoral arteries in dogs on low dose (162 mg/day) aspirin. Patency at 3 months was 37/48 (77%) for the ePTFE grafts and 44/48 (91.7%) for the CDC grafts. Fisher's exact test (two-tailed comparison) indicates the probability of superior CDC graft patency to be 95.5%. In the seven pairs of grafts in which one graft was occluded and the contralateral graft of another type was patent, the CDC graft was patent and the ePTFE graft was occluded in every instance. Explant histology and scanning electron microscopy showed greater collagenization, less residual platelet-fibrin and red blood cell deposits, and more frequent mid-graft endothelialization in the CDC grafts than in the ePTFE grafts.

Tacrolimus ointment, a potent immunosuppressive medication, was evaluated for efficacy in the treatment of perianal fistulas in dogs. Ten dogs with perianal fistulas were treated with topical tacrolimus ointment once to twice daily for 16 weeks. Full healing of the fistulas occurred in 50% and was noticeably improved in 90% of dogs.

Bone ingrowth into cementless acetabular components was evaluated in a canine total hip arthroplasty model, comparing components initially stabilized with polyglycolide-lactide screws with those initially stabilized with titanium screws. The acetabular shell was anchored with 2 polyglycolide-lactide screws in 16 dogs and with 2 titanium screws in 12 dogs. The dogs were followed and sacrificed at 7 weeks, 14 weeks, 10 months, or 15 months. Histomorphometric analysis of bone ingrowth into the weight-bearing dome of the acetabular shell was conducted. No difference was detected in mean bone ingrowth into the acetabular shell comparing the 2 screw groups. The results of this study do not support a significant advantage to the use of biodegradable screws for the initial stabilization of cementless acetabular components in canine total hip arthroplasty.

Fractures of the scapula can be classified into four groups on the basis of the anatomic structures involved: 1. Fractures of the glenoid (articular surface) 2. Fractures of the neck 3. Fractures of the acromion 4. Fractures of the body and spine

Introduction: Hemangiosarcoma is a malignant neoplasm of vascular endothelium occurring most frequently in older large breed dogs. Noncutaneous hemangiosarcoma is highly metastatic (>80% at diagnosis). Surgery is the primary method of treatment; however, even with adjuvant chemotherapy the prognosis for long-term survival is low. Hence, new therapies are needed. The sedative-hypnotic drug thalidomide (alpha-N-phthalimidoglutarimide) was withdrawn from general distribution in the 1960's after recognition of its teratogenicity and association with phocomelia. Recently, discredited thalidomide is making a comeback for its immunomodulatory and antiangiogenesis properties to treat inflammatory, infectious, and neoplastic diseases in people. Thalidomide can inhibit the proliferation of blood vessels associated with tumour development, thereby stopping or slowing tumour growth (similar to the devastating effect of the in utero interference with the blood supply of the developing limbs of the fetus). Therefore, the purpose of this study was to retrospectively obtain the results of thalidomide therapy for canine hemangiosarcoma. A prospective study for the use of thalidomide therapy for the treatment of canine hemangiosarcoma was also planned. Materials and Methods: Fourteen dogs with histologically diagnosed hemangiosarcoma were retrospectively entered into the study. Dogs were treated at 100–400 mg per day. Unfortunately, a legal, consistent source of thalidomide for treatment of dogs could not be obtained; therefore, the prospective study was postponed. Results: The median survival was 61 days with a range of 0 days to 2 years. Conclusions: Only limited efficacy data are available so far to define the clinical utility of thalidomide in canine hemangiosarcoma. However, in this pilot study there were prolonged responses to thalidomide in some patients which prompts a phase 2 investigation of thalidomide in canine hemangiosarcoma. The optimal dose and schedule of administration in dogs remains to be determined but the absence of myelosuppressive and other important adverse effects suggests thalidomide could be used in combination with chemotherapy. We conclude that thalidomide (or its analogues) could open the possibility for novel treatment that targets tumours and their microenvironment.

An important need in hemodialysis is a self-sealing prosthesis for vascular access with at least equivalent patency and biostability to expanded polytetrafluoroethylene (ePTFE) alternatives. The authors have developed a Corethane/polyester composite (CPC) graft with an inner blood interfacing layer of spun Corethane fibers (10-15 microns diameter; pore size 30-60 microns) impregnated with a gelatin-heparin complex and an outer soft tissue interfacing warp-knitted polyester sheath. Twenty-six CPC grafts (6 mm internal diameter; 25-30 cm length) and eight Gore-Tex ePTFE grafts (same dimensions) were implanted as femoral artery-to-vein shunts in dogs on low dose (162 mg/day) aspirin, and subjected to weekly dialysis needle punctures for up to 52 weeks. Patency was 73% (19/26 with 15 at 52 weeks) for the CPC grafts and 63% (5/8 at 52 weeks) for the ePTFE controls, with more favorable healing (e.g., less extensive mural thrombi) of the CPC grafts. The hemostasis time per needle pair after removal (3.1 min mean for CPC versus 21.2 min mean for ePTFE) and the blood loss in achieving hemostasis (5.7 g mean for CPC versus 47.9 g for ePTFE) documented the significant (p0.0001) performance advantages of the CPC prosthesis.

We performed an in vivo study in a canine model to compare the results of the use of a porous-coated collared femoral component with those of the use of a porous-coated collarless femoral component in total hip arthroplasties without cement. Our study focused on the comparative proximal strain pattern, bone ingrowth, and cortical porosity of the two types of prostheses. We used a trochanteric wire marker to measure subsidence. The use of the limb was assessed with gait analysis. Twelve weeks after the operation, the collarless components had significantly greater bone ingrowth proximally (p = 0.003) and were associated with significantly lower cortical porosity (p = 0.006). There were no differences between the groups with regard to either axial or hoop strain. While the group that had a collarless prosthesis had significantly less proximal-medial radiolucency (p = 0.03), there were no differences between the groups with regard to subsidence.

This project compared the effects of hydrocolloid (HC) and hydrogel (HG) occlusive dressings and a polyethylene (PE) semi-occlusive dressing on the healing of acute full-thickness skin wounds on the forelimbs of 10 dogs. All treatments resulted in a similar degree of healing at postoperative days 4 and 7. No significant differences existed in the number of wounds that were more than 90% healed at postoperative day 28 between the group treated with the HG dressing and the group treated with the PE dressing. There were significantly fewer wounds more than 90% healed at postoperative day 28 in the group treated with the HC dressing. Wounds under the HG dressing had the largest mean percentage of contraction at postoperative days 21 and 28. Wounds under the HG dressing also had the largest contraction/re-epithelialization ratio (postoperative days 21 and 28) compared with wounds under the PE and HC dressings. Wounds under the PE dressing had a significantly higher mean percentage of re-epithelialization than wounds under both occlusive dressings on postoperative days 14, 21, and 28. Wounds under the two occlusive dressings had exuberant granulation tissue present more often than wounds under the PE dressing. The two occlusive dressings had significantly higher bacterial counts on wounds compared with wounds under the PE dressing; analysis of variance (ANOVA), P = .0008. Wounds under the HC dressing showed the poorest healing in all parameters.

Cementless total hip arthroplasty was performed in 13 dogs. The acetabular component was anchored with two biodegradable devices (polylactic acid) in seven dogs and with two titanium screws in six dogs. At 14 weeks, histomorphometric determinations of bony ingrowth into the porous coating of the acetabular weight bearing dome was 54.4% when fixed with the biodegradable devices and 58.9% when fixed with the titanium screws (no statistically significant difference; p = 0.556). At the sites of fixation, less bony ingrowth occurred with the biodegradable devices. The use of biodegradable devices in total hip arthroplasty should overcome the potential metal corrosion of titanium screws that can lead to polyethylene wear.

We have developed a composite vascular prosthesis with the inner blood interfacing layer made of a porous elastomeric membrane of spun Corethane fibers (10-15 microns in diameter, pore size 30-60 microns) impregnated with a gelatin-heparin complex and an outer soft tissue interfacing warp knitted Dacron sheath. Forty-eight Corethane/Dacron composite (CDC) vascular grafts, 4 mm in diameter and 5 cm in length, and 48 expanded polytetrafluoroethylene (ePTFE) vascular grafts of similar size were implanted bilaterally as end to end interposition grafts on opposite sides in the carotid and femoral arteries in dogs on low dose (162 mg/day) aspirin. Patency at 3 months was 37/48 (77%) for the ePTFE grafts and 44/48 (91.7%) for the CDC grafts. Fisher's exact test (two-tailed comparison) indicates the probability of superior CDC graft patency to be 95.5%. In the seven pairs of grafts in which one graft was occluded and the contralateral graft of another type was patent, the CDC graft was patent and the ePTFE graft was occluded in every instance. Explant histology and scanning electron microscopy showed greater collagenization, less residual platelet-fibrin and red blood cell deposits, and more frequent mid-graft endothelialization in the CDC grafts than in the ePTFE grafts.

Because of its potential application to intestinal bladder reconstructions, the authors studied the functional and anatomic results of a modification of the Camey procedure. In this modification the enteric bladder replacement is sutured to the periphery of the prostatic capsule after the inner two-thirds of the prostate gland have been removed. In eight dogs postoperative functional studies revealed that all were continent and potent. Autopsy examination of the area of the intestinoprostatic anastomosis revealed that the prostatic fossa was lined by a transitional epithelial layer originating from the urethral stump and not by intestinal mucosa as might be expected. The results indicated that this modification is simpler technically than the original procedure, that it shortens the operating time and that it gives excellent functional results. If used in the context of bladder cancer, however, the procedure should be undertaken only in the presence of negative biopsies and brushings of the urethra before surgery, because the transitional epithelium lining the prostatic fossa represents a new area at risk later malignant transformation. Moreover, because of the potential importance of the area of prostatic fossa resurfaced postoperatively by urothelium, even patients with normal preoperative urethral biopsies and brushings who undergo such a procedure require careful follow-up with endoscopic examination, urethral biopsy and brushings and cytologic examination of the urine.

In this paper the development of a new experimental method tailored to investigate the lubricant film in sealing contacts is presented and discussed in detail. This technology is based on a new 3-Dimensional mapping technique achieved by image processing the fluorescent emission induced in the oil film of the sealing contact. — In a first step, the equipment for calibration was designed and used to optimise the optical system and the concentration of fluorescent dye. — In a second step, the lubricant film under a radial seal lip and its correlation to shaft speed and friction torque were studied.

Polyurethane vascular prostheses offer the potential of superior thromboresistance and reduced anastomotic hyperplasia compared to existing Dacron and ePTFE alternatives, but have suffered from susceptibility to biodegradation, with resulting mechanical failure. To address this problem, the authors have developed and evaluated a composite prosthesis comprised of: 1) an inner blood interfacing elastomeric porous membrane made from Corethane, a proprietary Shore 80A polyurethane like material substantially devoid of ether/ester linkages, with superior biostability over conventional polyether urethanes, spun into a nonwoven structure with fiber diameters 10-15 microns and pore sizes 30-60 microns filled with gelatin +/- heparin; and 2) an outer soft, tissue interfacing, warp knitted Dacron mesh bonded to the inner layer to assure long-term dimensional stability. Twenty 4 mm ID x 5 cm L composite prostheses, half with heparinized gelatin (the remainder nonheparinized) were implanted as femoral interposition grafts in 10 dogs. Four of the 10 nonheparinized grafts occluded. All 10 with heparin remained widely patent, with two explanted at 6 months showing vascularized connective tissue growth through the graft, in contrast to the giant cell inflammatory response to the Dacron mesh, with a substantially endothelialized neointima and no Corethane biodegradation. Of the 10 patent grafts at 1 year follow-up, none showed aneurysm formation. This vascular prosthesis provides compliance superior to ePTFE and Dacron alternatives, with excellent suture retention and good kink resistance, while combining the superior thromboresistance and tissue ingrowth properties of polyurethanes with the proven biostability of Dacron.

Urinary diversion by implantation of the ureters into an isolated segment of jejunum was evaluated in eight clinically normal male dogs. Total cystectomy and subtotal intracapsular prostatectomy were performed, and the intestinal loop was sutured to the prostatic remnant. General health, renal function, acid-base balance, urinary tract infection, and urinary continence were monitored during observation periods of 4 to 30 weeks. All dogs survived the observation period and seven were in excellent general health at the time of euthanasia. Six of the 16 ureterointestinal anastomoses were complicated by complete ureteral obstruction. Absorption of urea from the intestinal loop was speculated as the reason for significant increases in serum urea nitrogen concentrations in all of the dogs. Serum creatinine concentrations generally remained within the normal range, but were significantly increased from preoperative baseline values by week 30. There was dilation of 12 renal pelves and ureters in seven dogs. Urine bacterial cultures were positive in six dogs, but histologic evidence of pyelonephritis was present in only five kidneys. Ejaculation was not affected by the procedure, but epididymitis was present in five dogs. The dogs could urinate consciously and did not dribble urine continuously; however, they urinated hourly. While the procedure was well tolerated by the dogs, the frequency of urination makes this technique unacceptable for most household pets.

The ability of a pulsing magnetic field to accelerate wound healing was tested in rats. Full-thickness skin defects were created surgically in rats. A magnetoelectric coil applicator was used to deliver two 15 minute episodes of pulsing magnetic treatment daily to the rats at a level of 80 Gauss and 60 Hr. Healing was evaluated grossly and by light microscopy 7, 14, 22, 29, 42, and 56 days following wound creation. No significant change in rate of wound contracture or epithelialization was seen nor was there any microscopic evidence of enhanced collagen formation or cellular organization as compared with untreated wounds.

Eight healthy mongrel dogs were treated with half-body irradiation (HBI) in a pilot study to evaluate the technique and radiotolerance of different organs. Cranial and caudal half-body fields were established using the 13th thoracic vertebra as the dividing point. Under general anesthesia, either 7 or 8 Gray (Gy) were delivered to one half of the body using opposing radiation portals. The other half of the body was similarly treated 28 days later. The dogs were monitored for 12 months. Significant radiation effects included transient bone marrow suppression and radiation sickness. There were no serious or life-threatening problems, but the 8 Gy group consistently showed more severe clinical signs and histologic changes than the 7 Gy group. Total body irradiation in two fractions of 7 or 8 Gy given 1 month apart appears to be a safe treatment that can be developed for therapy in veterinary oncology.

In order to elucidate the mechanisms of neurogenic control of bone development and growth, the effects of traumatic and electric stimulation on the development, size, and shape of antler bone tissue were investigated. Unilateral growth of antler in a female deer was initiated after traumatic stimulation of the frontal bone. Electrical stimulation of antler nerves or antler periosteum resulted in an increase in more than 70% in antler length and over 40% in weight. Stimulation of antler nerves also resulted in abnormal shape of antlers. The role of periosteal nerves and the participation of the central nervous system in the responses to stimulation is discussed.

The extent of bone remodelling under metal fixation plates attached to bone by (i) normal screw fixation and (ii) bone ingrowth into a porous metallic surface underlayer sintered to the metal plate was investigated. Extensive bone remodelling was observed under the integrally bonded porous surface layered plate. This remodelling could be attributed to the more extensive stress transfer from bone to metal plate because of the good bone-to-implant bonding. The importance of stress shielding with high stiffness implants is demonstrated.

SummaryThirteen pairs of tibiae were excised from adult mongrel dogs following a mean recovery period of 24.2 weeks after unilateral total hip arthroplasty (THA). Prior to euthanasia, peak vertical dynamic load, as a percent of body weight, was determined for each limb at a walking pace. Four contiguous proximal sections and one transverse cortical midshaft section, 5mm thick, were harvested from each tibia. Contact Faxitron radiographs of the sections were quantified, using video digitizing software, to compare mean apparent density measures between the treated (THA) and intact limbs. There was a significant difference in mean apparent density of cancellous bone with the treated limb having a lower apparent density than the intact limb. The mean cortical area at the midshaft was significantly lower and the medullary area significantly higher among tibiae from the treated side, as compared to the contra-lateral tibiae. Resistance to bending and tension at the midshaft of each bone were determined using the second moment of area about cranio-caudal (Ix) and mediolateral (Iy) axes. The mean Iy values for the treated limbs were significantly lower than for the intact limbs. Therefore, measurable adaptive bone remodeling appears to be present in both cancellous and cortical bone in the tibia due to decreased mechanical loading.

In a series of twenty-two cats with femoral fractures repaired by internal fixation, four cases of quadriceps contracture (18.2%) were observed. Each case of contracture involved a midshaft fracture with extensive soft tissue injury. Repair with intramedullary pins and cerclage wires had been performed in each case. Exuberant callus production was noted in two cases, while in another quadriceps contracture followed injury to the ischiatic nerve. Contracture was evident two weeks postoperatively. Physiotherapy proved ineffective and surgical intervention was not undertaken as all cases were weightbearing on the affected limb.

In a Phase I-II study, half-body radiotherapy was used to treat 14 dogs with multicentric lymphoma. Using this technique, a radiation dose of 7 Gray (Gy) was delivered to one half of the body in a single exposure. The other half of the body was treated approximately 28 days later. Of 14 treated dogs, 11 (79%) had a measurable decrease in tumor size. Five dogs achieved a complete or partial remission with a mean duration of 102 and 54 days, respectively. In predicting response to therapy, poor prognostic factors included large tumor burdens, advanced disease stage, and chemotherapy-resistant tumors. Side effects of treatment were divided chronologically into acute (radiation sickness, tumor lysis), subacute (bone marrow suppression), and chronic (radiation pneumonitis, lymphoma-cell leukemia) syndromes. Complications were more severe in tumor-bearing dogs when compared with healthy control animals. Dogs with small tumor burdens and minimal internal disease had fewer complications compared with those with more advanced disease.

The results of surgical therapy in 15 dogs with histologically confirmed nasal tumors were analyzed retrospectively and compared to previous reports. Median survival time for all dogs was seven months. When adjusted for nontumor-related deaths, median survival increased to nine months. These values are two to three times longer than previous reports. To determine possible prognostic indicators, tumor stage, location, and histological type were compared to survival time. Dogs with unilateral nasal tumors had a median survival of 11 months, as compared to three months for dogs with bilateral tumors (p = 0.005). Tumor stage and histological type were not significant factors in comparing survival times.

The influence of mechanical properties on the acute and chronic success of vascular grafts remains the subject of considerable debate. It is widely held that the matching of some set of mechanical properties at the anastomosis between a natural vessel and a vascular graft will optimize the likelihood of clinical sucess. Investigations in this area have largely concentrated on compliance (defined as the percentage change in diameter per unit change in pressure) as the parameter to be matched across the anastomosis. However, compliance represents only one out of a set of candidate parameters (including elastic moduli, Poisson ratios, admittance, distensibility, and hydraulic impedance among others) and there is no definitive evidence that it is in any way the most important mechanical parameter to be considered. As well, the concentration on compliance has resulted in the failure to examine the importance of the longitudinal behavior of the vascular grafts. The longitudinal properties of any vessel can profoundly influence the observed circumferential behavior; however, this is, at best, only implicit in the onedimensional compliance parameter.

Porous coated canine femoral hip replacement implants were evaluated for biological fixation by bone ingrowth and the effect of the extent of porous coating on bone modeling. The Co-Cr alloy implants were either fully porous coated or coated only on the proximal 40% of the stem. Two implants of each type were studied 9, 16, and 36 months after surgery. Implant fixation and bone modeling were assessed radiographically throughout the implant periods and histologically after the test animals were killed. All 12 implants appeared stably fixed within the femur and were bone-ingrown in the porous region. Radiographic features such as proximal medial and anterior cortical thinning, proximal cancellous bone hypertrophy, and new endosteal bone formation near the stem tip were noted within the first postoperative year, with no appreciable change thereafter. The extent of proximal cortical thinning varied from virtually none to as much as 40%, being more prominent with the proximally coated implants at 16 months and with the fully coated implants at 36 months. Of consistent note was cancellous hypertrophy at the junction of porous and smooth implant surfaces with proximally coated implants and new endosteal bone formation and ingrowth at the stem tip of fully coated implants. These results indicate that the proximally porous-coated implant design causes increased proximal stress transfer, but this does not necessarily preclude proximal cortical resorption.

A percutaneous implant for the attachment of an artificial limb has been designed and tested in 14 pigs. Firm fixation to beone was achieved with the porous-surface layered metal intramedullary stem design in some cases. Dacron velour was used at the soft tissue interface. Evidence of soft tissue ingrowth was seen. However, the velour was unable to maintain adequate epithelial adhesion to form an anatomical seal and a barrier to bacteria.

A case of discospondylitis and orchitis associated with high Brucella titre in a dog is presented. Clinical signs included intermittent pain, poor appetite and a decreased level of physical activity. Radiographic evidence of discospondylitis was found. Histopathological findings on the testes are included. Treatment regime and clinical progress are given. Diagnosis and treatment of B. canis are described and a brief review of the treatment of discospondylitis is presented.

Eight healthy mongrel dogs were treated with half-body irradiation (HBI) in a pilot study to evaluate the technique and radiotolerance of different organs. Cranial and caudal half-body fields were established using the 13th thoracic vertebra as the dividing point. Under general anesthesia, either 7 or 8 Gray (Gy) were delivered to one half of the body using opposing radiation portals. The other half of the body was similarly treated 28 days later. The dogs were monitored for 12 months. Significant radiation effects included transient bone marrow suppression and radiation sickness. There were no serious or life-threatening problems, but the 8 Gy group consistently showed more severe clinical signs and histologic changes than the 7 Gy group. Total body irradiation in two fractions of 7 or 8 Gy given 1 month apart appears to be a safe treatment that can be developed for therapy in veterinary oncology.

Load-bearing porous-surfaced implants in dogs which failed were not incorporated by bone ingrowth. The implants were incorporated only by fibrous tissue ingrowth. Collagen fiber orientation within this fibrous tissue and Sharpey's fiber-like features at the interface between the fibrous tissue and a surrounding layer of dense bone suggest the adequacy of the fibrous tissue attachment for support of a loaded implant. The surrounding dense bone layer could be distinguished radiographically within three months of the operation. This radiopaque line is similar to that observed around some porous surfaced hip implants in humans. Observations of animal mobility up to six months postoperatively suggest that fibrous connective tissue growth into porous implants can provide adequate mechanical support for weight-bearing dogs.

Load-bearing porous-surfaced implants in dogs which failed were not incorporated by bone ingrowth. The implants were incorporated only by fibrous tissue ingrowth. Collagen fiber orientation within this fibrous tissue and Sharpey's fiber-like features at the interface between the fibrous tissue and a surrounding layer of dense bone suggest the adequacy of the fibrous tissue attachment for support of a loaded implant. The surrounding dense bone layer could be distinguished radiographically within three months of the operation. This radiopaque line is similar to that observed around some porous surfaced hip implants in humans. Observations of animal mobility up to six months postoperatively suggest that fibrous connective tissue growth into porous implants can provide adequate mechanical support for weight-bearing dogs.