Effects of EGF, FGF, and PDGF on Canine Chondrocytes in Three-Dimensional Culture

Three-dimensional (3-D) culture of chondrocytes has been shown to promote cell proliferation, differentiation, and production of matrix while providing for cell morphology and matrix characteristics that resemble normal articular cartilage (1-3). In a recently published study, enhanced glycosaminoglycan (GAG) production was demonstrated in canine chondrocytes in 3-D culture on cancellous bone substrate (3). The effects of growth factors known to be present in cryopreserved bone were suggested to be responsible. Various growth factors including epidermal growth factor (EGF), fibroblast growth factor (FGF), and plateletderived growth factor (PDGF) have been shown to enhance chondrocyte DNA production, mitotic activity, and matrix production (5-10). The objective of the study reported here was to evaluate the effects of one concentration of EGF, FGF, and PDGF on canine chondrocyte proliferation and production of normal matrix constituents in 3-D culture.

Canine articular chondrocytes were cultured in three-dimensional medium for 25 days. EGF, FGF, and PDGF were added to the culture medium. Chondrocytes in 3-D culture maintained viability and differentiation. Cell morphology and matrix production resembled that of intact hyaline cartilage. Significant differences with respect to cell counts, glycosaminoglycan concentration, or collagen type II immuno-reactivity as the result of added growth factors were not found.

Treatment of canine hemangiopericytomas with photodynamic therapy

BACKGROUND AND OBJECTIVES

Canine hemangiopericytomas are a commonly occurring neoplasm with a clinical course of recurrence after surgical removal. This study sought to evaluate Photochlor (HPPH) photodynamic therapy (HPPH-PDT) as an adjuvant therapy to prevent recurrence of tumor after surgical removal.

STUDY DESIGN/MATERIALS AND METHODS

Sixteen dogs with naturally occurring hemangiopericytomas were treated with surgical removal of the tumor followed by PDT using Photochlor as the photosensitizer. Photochlor was injected intravenously at a dose of 0.3 mg/kg. Forty-eight hours later the treatment consisted of surgical removal of the tumor followed by HPPH-PDT.

RESULTS

Nine dogs (56%) had recurrence of tumor from 2 to 29 (median 9) months after treatment. These results are comparable or not as good as other forms of therapy.

CONCLUSIONS

Photochlor photodynamic therapy applied after surgery appears to have no advantage over other forms of therapy in regards to preventing recurrence. Delayed wound healing and infections are problematic and make HPPH-PDT an undesirable addition to surgery for the treatment of this tumor type.

Cortical bone healing following laser osteotomy using 6.1 microm wavelength

BACKGROUND AND OBJECTIVE

Use of laser wavelengths in the 6.1 microm (amide I) to 6.45 microm (amide II) regions and a macropulse width of 4.0 microseconds delivered by a computer-controlled delivery system have produced clean, deep cortical bone ablations with minimal collateral thermal injury and no char formation. The purpose of this study was to evaluate the healing of cortical bone following 6.1 microm wavelength laser osteotomy using a 4.0 microsecond pulse, and compare that response to the response of similar osteotomies made with a standard pneumatic surgical bone saw.

STUDY DESIGN/MATERIALS AND METHODS

Sixteen mature rabbits were divided equally into 2, 4, 6 and 8-week post-surgical survival groups. A nitrogen driven sagittal bone saw and an FEL generating 6.1 microm wavelength in 4.0 microsecond macropulses of 22.5 +/- 2.5 mJ/pulse directed into a 200 microm diameter spot were used to make 6.6 mm linear cuts into rabbit tibial cortex, and the healing response over time was monitored. Bone saw cuts were made halfway through the thickness of the cortex. Laser cuts were directed by a computer-controlled delivery system, and were either partial or full thickness cortical cuts. Location of the cortical bone cuts (saw or laser, partial or full thickness cut, proximal or distal, medial right or medial left tibia) were randomly assigned. At each predetermined post-surgical time point, rabbits of the appropriate group were euthanized, and the tibias of each subject collected, processed for histologic evaluation, and analyzed by light microscopy.

RESULTS

At 2 weeks post-surgery, bone saw cuts showed no evidence of a healing response, while both the partial and full laser cut sites were filled with trabecular bone and primitive bone marrow. By 4 weeks post-surgery, the bone saw cuts showed filling of the defect with trabecular bone and primitive marrow, and an intense osteonal remodeling of the original cortex adjacent to the cuts was evident. All laser cut defects were filled, reactive periosteal bone was being converted to osteons and consolidating, and secondary osteons were appearing in the original cortex. At 6 weeks following surgery, the bone saw defects were filed with a mixture of woven and lamellar bone. All laser defects were filled with lamellar osteons and woven bone, the osteons were remodeling from primary to secondary osteons. By 8 weeks following the surgery, all bone saw and laser cut specimens revealed complete healing.

CONCLUSIONS

Histologic evaluation of osteotomy sites made in skeletally mature rabbit tibia using the 6.1 microm wavelength, 4.0 microsecond macropulse FEL, delivered at 6 Hz at the osteotomy site, reveals a healing response which is at least as good as the healing of bone saw osteotomies, and appears to proceed at a faster rate during the first 2-4 weeks following surgery.

Treatment of canine oral squamous cell carcinomas with photodynamic therapy

Eleven dogs with naturally occurring oral squamous cell carcinomas were treated with photodynamic therapy (PDT) using Photochlor (HPPH) as the photosensitizer. The largest length of the tumours measured in a two-dimensional plane ranged from 0.9 to 6.8 cm. Seven of the tumours invaded underlying bone as determined by radiograph appearance. Photochlor was injected intravenously at a dose of 0.3 mg kg(-1). Forty-eight hours later the tumours were treated. Tumours with a surface to base depth of greater than 1 cm were surgically reduced to less than 1 cm. Irradiation with 665 nm light with an energy density of 100 J cm(-2) was administered. Eight dogs were considered cured with no tumour recurrence for at least 17 months after treatment. Local treatment of oral squamous cell carcinomas with PDT appears to give results similar to those obtained with surgical removal of large portions of the mandible or maxilla. The cosmetic results with PDT are superior to those of radical surgical removal. The new sensitizer, Photochlor, appears effective for oral squamous carcinomas with results similar to those reported for other sensitizers.

Comparison of cortical bone ablations by using infrared laser wavelengths 2.9 to 9.2 microm

BACKGROUND AND OBJECTIVE

The purpose of this study was to compare the ablation of cortical bone at wavelengths across the near and midinfrared region.

STUDY DESIGN/MATERIALS AND METHODS

An free electron laser generating 4-micros macropulses at specific wavelengths between 2.9 and 9.2 microm was used to ablate cortical bone. The same pulse intensity, repetition rate, radiant exposure, number of pulses, and delivery was used for each wavelength. Tissue removal, collateral thermal injury, and morphologic characteristics of the ablation sites were measured by light and scanning electron microscopy, and compared with the infrared absorption characteristics of cortical bone.

RESULTS

Within the parameters used, bone ablation was found to be wavelength dependent. Incisions were deepest where protein has strong absorption, and were most shallow where mineral is a strong absorber. No char was observed on ablation surfaces where 3.0, and 5.9-6.45 microm wavelengths were used.

CONCLUSIONS

The use of wavelengths in the 6.1-microm amide I to 6.45-microm amide II region, with the pulse characteristics described, were the most efficient for cutting cortical bone and produced less collateral thermal injury than cutting with a surgical bone saw. This study confirms previous observations that the ablation mechanism below plasma threshold is consistent with an explosive process driven by internal vaporization of water in a confined space and demonstrates that ablation is enhanced by using wavelengths that target the protein matrix of cortical bone.

Closed reduction and lag screw fixation of sacroiliac luxations and fractures

OBJECTIVE

To describe a technique for closed reduction and percutaneous insertion of a lag screw for fixation of sacroiliac fracture-luxations, and to report the success of this technique in stabilizing sacroiliac fracture-luxations.

STUDY DESIGN

A retrospective clinical study.

STUDY POPULATION

13 consecutive client-owned dogs with sacroiliac fracture-luxations.

METHODS

Sacroiliac fracture-luxations were stabilized by using a closed reduction and percutaneous lag screw fixation technique. Preoperative, postoperative, and last re-examination radiographs were used to assess the location and number of pelvic injuries, other orthopedic injuries, percent reduction of the sacroiliac joint, percent sacral width screw depth, position of the screw, pelvic canal diameter ratio, hemipelvic canal width ratio, and complications. Information on signalment, weight, weight-bearing status, neurologic status, and complications was obtained from the medical record.

RESULTS

Mean percent reduction of the sacroiliac joint was 92.33%. All screws were placed within the sacral body with a mean screw depth/sacral width of 79.03%. No screw loosening occurred. Mean pelvic canal diameter ratios were 0.99, 1.20, and 1.14 preoperatively, immediately postoperatively, and at the last re-examination, respectively. Nine of 13 dogs were willing to walk on the ipsilateral rear leg the day after surgery.

CONCLUSIONS

Closed reduction and percutaneous insertion of a lag screw for stabilization of fracture-luxation of the sacroiliac joint is an acceptable method of repair.

CLINICAL RELEVANCE

Sacroiliac fracture-luxations can be successfully reduced and stabilized using a minimally invasive technique.

Biomechanical evaluation of a crimp clamp system for loop fixation of monofilament nylon leader material used for stabilization of the canine stifle joint

OBJECTIVE

To test a crimp clamp system designed to secure monofilament nylon leader (MNL) material commonly used as lateral fabellotibial sutures (LFS) in extra-articular stabilization of the canine stifle joint.

STUDY DESIGN

In vitro biomechanical tests of MNL loops secured with either the crimp clamp system or knots were performed. Suture loops (n = 94) were created from 27.3 kg tensile strength MNL and fastened with knots or crimp clamps. Tests were conducted on steam-sterilized, ethylene-oxide-sterilized, and nonsterilized MNL sutures. Loops were evaluated in single load tests and cycled tests. Values for load to failure, initial loop tension, loop elongation, mode of failure, and point of failure were determined.

RESULTS

Crimp-clamped loops were superior to knotted loops in all parameters tested in both cycled and noncycled tests. Loop failure generally occurred by breaking within 3 mm of the fixation in both clamped and knotted tests. Loop elongation after cycling was greater in the knotted loops compared with clamped loops (P < .001). Load to failure was greater in clamped tests than in knotted tests (P < .001), regardless of sterilization technique used. Significantly higher initial loop tension could be achieved with the clamp system compared with knot fixation (P < .001).

CONCLUSIONS

The crimp clamp system provides superior in vitro loop fixation characteristics compared with knot fixation in 27.3 kg test MNL.

CLINICAL RELEVANCE

Based on the results of biomechanical testing and the known biocompatibility of the system's implant components, clinical trials using the crimp clamp system are warranted.

Pulp remains viable following vital amputation of the mesio-buccal root of the maxillary fourth premolar in dogs

Vital amputation of the mesio-buccal root of the maxillary fourth premolar (P4) was performed bilaterally in 8 dogs. Histopathologic evaluation of the tooth structure revealed normal pulp in the remaining mesio-buccal, mesio-palatal, and distal roots and crown during a mean follow-up period of 3.5 +/- 1.9 months. Amputation site healing was characterized by a reparative dentin bridge produced by odontoid cells. Tunnel defects were observed in 13 of 16 (81%) dentin bridges. It is concluded that the pulp of a tri-rooted, periodontal disease-free tooth remains viable during a 6-month period following vital root amputation. These results point to the intriguing possibility that this may also occur in humans, however, this needs to be directly tested in man.

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.

Surgical treatment of osteoarthritis

Surgical treatment of OA is appropriate when conservative therapy fails or is inadequate. The veterinary orthopedist's goals in treatment should be to alleviate pain, maintain function, and prevent or remove the potential for further degeneration of the joint. Currently, in veterinary surgery, THR and femoral head and neck excision are the primary treatments for OA of the coxofemoral joint. Other joints are treated primarily by arthrodesis or excision arthroplasty. Arthroscopy is proving to be a valuable tool in the diagnosis and treatment of OA, and total stifle and elbow replacement and cartilage resurfacing through chondrocyte grafting are on the horizon as potential treatment options.

Evaluation of percutaneous gastrostomy as a technique for permanent gastropexy

OBJECTIVE

This study was designed to evaluate right-sided percutaneous endoscopic gastrostomy (PEG) as a method for creation of a permanent gastropexy.

STUDY DESIGN

Percutaneous endoscopic gastrostomy adhesions were evaluated by gross examination and by mechanical testing and the results were compared with those obtained by conventional incisional gastropexy.

ANIMALS OR SAMPLE POPULATION

Fourteen mixed-breed dogs.

METHODS

Incisional gastropexies were performed on the dogs of group one (N = 7) and PEG tubes were placed in the dogs of group 2 (N = 7). All skin sutures (group 1) and PEG tubes (group 2) were removed on day 14. The animals were maintained for an additional 44 days before euthanasia and immediate necropsy. Gastropexy adhesions were evaluated and collected for biomechanical evaluation using a materials testing machine.

RESULTS

The duration of the procedure for group 2 was less (32.86 min +/- 7.65) than for group 1 (56.29 min +/- 8.28). The number of complications was not significantly different between group 1 and group 2 (P = .103). Gastroperitoneal adhesions were present in 7 of 7 dogs in group 1 and 4 of 7 dogs in group 2. The adhesion lengths and widths were significantly lager in dogs in group 1 compared with those in group 2. The adhesions present in group 1 dogs sustained significantly greater tensile loads to failure (61.98 +/- 14.65 N), compared with the adhesions present in group 2 dogs (22.31 +/- 26.87 N).

CONCLUSIONS

Right-sided PEG inconsistently formed a weak gastropexy and the procedure was associated with a trend toward greater morbidity than incisional gastropexy.

CLINICAL RELEVANCE

Right-sided PEG is not recommended as a means of prophylactic gastropexy.

Three-dimensional culture of canine articular chondrocytes on multiple transplantable substrates

OBJECTIVE

To determine the effects of transplantable substrates on canine chondrocytes grown in three-dimensional culture.

ANIMALS

3 canine cadavers.

PROCEDURE

Articular cartilage harvested from canine cadavers was used to obtain chondrocytes for primary culture. Subcultured chondrocytes were grown in agarose alone (AG), or in agarose on canine cancellous bone (CB), polypropylene mesh, or oxidized regenerated cellulose substrate. Cell proliferation, proteoglycan and glycosaminoglycan (GAG) production, and collagen production were assessed on days 3, 6, 10, 15 and 20.

RESULTS

Chondrocytes from groups AG and CB proliferated and produced matrix over the entire 20-day study period. Group-CB chondrocytes had significantly more GAG than did chondrocytes of all other groups on days 6 (P = 0.0297) and 15 (P = 0.00272). Those of groups AG and CB contained significantly (P = 0.0235) more GAG on day 20. Chondrocytes of the polypropylene mesh group proliferated and produced matrix through day 10 in culture, but were no longer viable and had no matrix production on days 15 and 20. Regenerated cellulose appeared to be toxic to canine chondrocytes during all stages of in vitro three-dimensional culture.

CONCLUSIONS

Three-dimensional culture of canine chondrocytes in agarose appears to produce favorable results with respect to chondrocyte proliferation and matrix production. Canine CB appears to have beneficial effects with regard to early GAG synthesis. Polypropylene mesh and oxidized regenerated cellulose had detrimental effects on cellular proliferation and matrix production.

Bioavailability of lead to juvenile swine dosed with soil from the Smuggler Mountain NPL Site of Aspen, Colorado

Bioavailability of lead (Pb) has become an issue in quantifying exposure of sensitive populations and, where necessary, establishing cleanup levels for contaminated soil. Immature swine were used as a model for young children to estimate the degree to which Pb from two fully characterized composite samples from the Smuggler Mountain Superfund Site in Aspen, Colorado may be bioavailable to resident children. The composite soils contained 14,200 and 3870 micrograms Pb/g of soil. Relative and absolute enteric bioavailabilities of Pb in soil (oral dose groups of 75,225, and 675 micrograms Pb/kg body wt/day) were estimated by comparison with an orally administered soluble Pb salt (lead acetate = PbAc2.3H2O) (dose groups of 0, 75, and 225 micrograms Pb/kg body wt/day) and an intravenously administered aqueous solution of Pb (100 micrograms Pb/kg/ day) from the same trihydrate salt administered daily for 15 days to 50 juvenile swine. The biological responses (area under the blood Pb concentration-time curve, and the terminal liver-, kidney-, and bone-lead concentrations) produced by Pb from PbAc2.3H2O and lead-contaminated soils were determined. This study revealed Pb from soil containing 14,200 micrograms Pb/g of soil had a bioavailability relative to Pb from PbAc (RBA), ranging from 56% based on the area under the blood lead concentration-time curve (AUC) versus dose, to 86% based on calculations from liver-Pb loading versus dose. Similarly, Pb from soil containing 3870 micrograms Pb/g of soil had an RBA ranging from 58% based on the AUC versus dose, to 74% based on calculations from liver- and kidney-Pb loading versus dose. Bioavailability of Pb in soils may be more or less than EPA's default RBA of 60%, therefore, measuring site-specific RBAs provides a basis for improved exposure and risk assessment.

Atraumatic rupture of the gastrocnemius muscle after corticosteroid administration in a dog

A 6-year-old spayed female Shetland Sheepdog was referred for evaluation of lameness, muscle atrophy, and a partial plantigrade stance of the right hind limb of 5 weeks' duration. Without history of trauma, atraumatic rupture of the right gastrocnemius muscle was diagnosed. Surgical repair was unsuccessful. The dog then developed signs of hyperadrenocorticism. Results of ACTH stimulation and low-dose dexamethasone suppression tests were consistent with iatrogenic adrenal suppression. One deleterious effect of excessive use of corticosteroids on muscle and connective tissue is degenerative myopathy. Steroid-induced myopathy with subsequent rupture of the gastrocnemius muscle was suspected in this dog. Clinical signs of myopathy most often develop with use of triamcinolone acetonide; therefore, care should be taken when administering this and other corticosteroids.

Pharmacokinetics of pyropheophorbide-a-hexyl ether in the dog

BACKGROUND AND OBJECTIVES

Pyropheophorbide-a-hexyl ether (HPPH) is a new compound being investigated for use as a photosensitizer for photodynamic therapy; however, the pharmacokinetics are not known for any of the target species likely to be treated with this drug. The objective of this study was to determine the pharmacokinetic parameters of this drug prior to institution of a clinical trial in canine patients with various cancers.

STUDY DESIGN, MATERIALS AND METHODS

HPPH (0.3mg/kg i.v.) was administered to 12 dogs and blood samples were drawn at intervals for 24 hours and plasma HPPH concentrations were determined. Pharmacokinetic parameters were calculated for each dog.

RESULTS

No evidence of toxicity was noted in any dog. The mean half-life was calculated to be 26.98 +/- 2.35 hrs. The mean clearance was 5.061 +/- 0.214 ml/hr/kg. The mean volume of distribution of the central compartment was 0.069 +/- 0.003 L/kg, and the mean steady state volume of distribution was 4.47 +/- 0.25 L/kg.

CONCLUSION

The conclusion is that 0.3 mg/kg HPPH injected intravenously resulted in measurable plasma levels for 24 hrs, and resulted in no detectable adverse reactions.

General management considerations for the trauma patient

Proper evaluation, nursing care, physical therapy, and attention to the patient's general comfort are essential to the successful management of animals with severe trauma. Evaluation is important because failure to identify all injuries early in the management of a trauma patient may have unfavorable effects on the eventual outcome of the case. Once therapy is underway, ensuring the patient's comfort, maintaining fluid and electrolyte balance, and providing a well-planned rehabilitation program are essential to speed an enhance the recovery of these patients.

Percutaneous iodine-125 seed implantation for carcinoma of the prostate

This study was performed to assess the early results of treating stages T1-T3 adenocarcinoma prostate with either Iodine-125 (125I) implant alone (Group 1), for smaller more well differentiated cancers, or with low dose external beam radiation followed by a 125I boost (XRT + 125I) (Group 2) for larger less well differentiated tumours. Eighty-six patients were followed for between 11 and 60 months with a mean follow up of 26.1. All patients were followed by regular prostate specific antigen (PSA) evaluations, and digital rectal examinations (DRE). Eighty patients had a follow-up biopsy at 1 year. Prostate specific antigen progression-free survival (PSA-PFS) was determined and defined. Complications and potency were also assessed. Early results of 125I prostate seed implantation are very promising especially for selected cases of localized carcinoma.

Effects of temperature and storage time on pin pull-out testing in harvested canine femurs

Effects of temperature and storage time on canine bone-transfixation pin specimens were tested by comparing pin pull-out forces. A total of 16 femurs from 8 mature dogs were tested. Five nonthreaded Steinmann pins were placed through both cortices in the diaphysis of each femur. The femurs were then sectioned transversely between each pin, with a bone-pin specimen placed evenly into each of 5 groups prior to biomechanical testing. Four bone-pin specimen groups were stored at -20 or -70 C for 14 or 28 days, while 1 specimen group was immediately tested. Pull-out forces for frozen groups were compared with pull-out forces for the fresh group. Using two-way ANOVA, there was no statistical difference in mean axial-extraction forces among bone-pin specimens in any of the tested groups. It is concluded that acute pin pull-out forces are not significantly affected by freezing temperature or time. However, specimens stored at -20 C for as few as 14 days had a trend for increased pull-out forces, compared with freshly harvested specimens. Therefore, the authors recommend storage of bone-pin specimens at -70 C when possible.

Detailed preliminary analysis of 125iodine implantation for localized prostate cancer using percutaneous approach

Recent developments have permitted accurate seed placement and dosimetry for interstitial brachytherapy of selected patients with localized prostate cancer. We present our experience with 76 patients divided into 2 groups. Group 1 included 45 patients with smaller, more well differentiated tumors, usually less than 2 cm. in diameter on digital rectal examination or transrectal ultrasound and a Gleason score of less than 7 who were treated with 125iodine alone. Group 2 consisted of 31 patients with localized tumors greater than 2 cm. in diameter and/or a Gleason sum equal to or greater than 7 who were treated with low dose external beam radiation followed by 125iodine boost 4 weeks later. Complete clinical progression-free survival, including prostate specific antigen, digital rectal examination and biopsy, was 51% for group 1 and 63.3% for group 2, with a mean followup of 26.3 months. Prostate specific antigen progression-free survival was 97.7% for group 1 and 94.7% for group 2. These results appear to be superior to external beam radiation only although longer followup is needed to substantiate these favorable early results. The procedures were well tolerated with good potency sparing. They were performed on an outpatient or short stay basis and provided a good alternative to external beam radiation only or hormonal treatment for select patients with localized prostate cancer who may not be candidates for radical prostatectomy.

Detailed preliminary analysis of 125iodine implantation for localized prostate cancer using percutaneous approach

Recent developments have permitted accurate seed placement and dosimetry for interstitial brachytherapy of selected patients with localized prostate cancer. We present our experience with 76 patients divided into 2 groups. Group 1 included 45 patients with smaller, more well differentiated tumors, usually less than 2 cm. in diameter on digital rectal examination or transrectal ultrasound and a Gleason score of less than 7 who were treated with 125iodine alone. Group 2 consisted of 31 patients with localized tumors greater than 2 cm. in diameter and/or a Gleason sum equal to or greater than 7 who were treated with low dose external beam radiation followed by 125iodine boost 4 weeks later. Complete clinical progression-free survival, including prostate specific antigen, digital rectal examination and biopsy, was 51% for group 1 and 63.3% for group 2, with a mean followup of 26.3 months. Prostate specific antigen progression-free survival was 97.7% for group 1 and 94.7% for group 2. These results appear to be superior to external beam radiation only although longer followup is needed to substantiate these favorable early results. The procedures were well tolerated with good potency sparing. They were performed on an outpatient or short stay basis and provided a good alternative to external beam radiation only or hormonal treatment for select patients with localized prostate cancer who may not be candidates for radical prostatectomy.

Articular fractures of the distal portion of the humerus in Vietnamese pot-bellied pigs: six cases (1988-1992)

Medical records of 6 Vietnamese pot-bellied pigs with articular fractures of the distal portion of the humerus were reviewed. Evaluation of the medical records did not reveal a sex predilection. All fractures were associated with minor traumatic episodes in young pigs. Of 6 fractures involving the humeral condyle, 4 involved the medial portion, 1 involved the lateral portion, and 1 was a Y-shaped fracture. Five of the pigs underwent surgical repair of the fracture, and all 5 did not have signs of lameness at follow-up evaluations (mean, 11 months). Of 4 pigs that had follow-up radiography, all had evidence of mild to moderate degenerative joint disease. Articular fractures of the distal portion of the humerus should be considered as a differential diagnosis in all Vietnamese pot-bellied pigs with forelimb lameness, even if the trauma sustained appeared mild. Surgical repair in Vietnamese pot-bellied pigs is straightforward, and excellent clinical results can be expected.

Comparison of a biofragmentable intestinal anastomosis ring with appositional suturing for subtotal colectomy in normal cats

A subtotal colectomy was performed on 12 normal adult cats using an interrupted apposing suture pattern of monofilament polyglyconate (n = 6) or a biofragmentable intestinal anastomosis ring (Valtrac, Davis and Geck Company, Danbury, CT) (n = 6) composed of polyglycolic acid and barium sulfate. Abdominal radiographs were made daily, beginning 10 days after surgery, to determine fragmentation rates of the anastomosis ring. The cats were euthanatized 30 days after surgery, and a gross and histopathological evaluation of anastomotic healing and stricture formation was performed. The technique for implantation of the anastomosis ring was easy to learn and required only two purse string sutures to complete. Intraoperative complications associated with the anastomosis ring were minor, and included problems with purse string suture placement, small serosal tears, and spasms of the colon that reduced the lumenal diameter. There were no intraoperative complications in the cats with sutured anastomoses. Postoperative recovery was uneventful in all cats. The anastomosis rings fragmented 12.2 +/- 1.1 days (mean +/- standard deviation [SD]) after implantation and passed in the stool 3.8 +/- 1.9 days later without clinical signs in five of six cats. There were no statistically significant differences between the time required to perform the anastomosis (P = .348), postmortem gross anastomosis grades (P = .088), or percent of lumenal stricture (P = .178) between the two groups. Histologically, the only significant differences were an increased muscular inversion in the anastomoses performed using the fragmentable ring (P = .039) and an increased muscular eversion in the sutured anastomoses (P < .001) compared with normal colonic architecture.

Effects of intra-articular chlorhexidine diacetate lavage on the stifle in healthy dogs

Eight dogs were determined to be orthopedically normal on the basis of prelavage physical examination, stifle radiography, synovial fluid analysis, and force plate analysis (peak vertical force normalized for body weight, and time on the force plate). Each dog had 1 stifle randomly assigned to be lavaged with 100 ml of a commercially available 0.05% (w/v) chlorhexidine diacetate solution, and the contralateral stifle was lavaged with lactated Ringer's solution. Difference was not detected between the chlorhexidine diacetate and lactated Ringer's solution-treated joints, with regard to results of synovial fluid analysis and clinical lameness evaluations on days 4 and 8 after lavage. Chlorhexidine diacetate caused a more intense synovitis than did lactated Ringer's solution, as determined by histologic evaluation of synovial membrane specimens after necropsy on day 8; however, a difference in the intensity of toluidine blue staining of articular cartilage was not found between treatments. Chlorhexidine diacetate, as a 0.05% (w/v) solution, cannot be recommended as a joint lavage fluid until the duration of inflammatory changes in the synovial membrane are determined or until the chemical constituents of chlorhexidine diacetate causing the synovitis can be identified and removed.

Stifle joint anatomy and surgical approaches in the dog

This article reviewed the pertinent anatomy and surgical approaches of the canine stifle joint. Anatomically correct approaches to this joint provide for relatively atraumatic entry into the joint, while providing adequate exposure to complete the intra-articular parts of the surgical procedure. Atraumatic surgical exposures provide for less postoperative pain and a better outcome to any surgical procedure.

Evaluation of the caudoventral portion of the mandible as a donor site for corticocancellous bone for periodontal surgery in dogs

Corticocancellous bone graft was obtained from the caudoventral portion of the mandible of 8 dogs. The recipient site was an alveolar jugal and alveolar defect from vital root amputation of the mesiobuccal root of the maxillary fourth premolar. Anatomic observations of 20 canine cadavers indicated that guidelines for harvesting bone from the caudoventral portion of the mandible of dogs were the mesial aspect of the masseteric fossa, the distal aspect of the roots of the first mandibular molar, and the ventral aspect of the mandibular canal. The mean weight of corticocancellous bone harvested was 0.4 +/- 0.1 g. Harvested corticocancellous bone was adequate to fill recipient sites measuring a mean volume of 105.0 +/- 28.5 mm3. Histologic evaluation of the recipient site revealed progressive osseous integration of the bone-graft site during a mean follow-up period of 3.5 +/- 1.9 months. There was normal bone healing of the donor site without adverse effects on the mandibular molars or neurovascular structures of the mandibular canal. Vital amputation sites receiving silver amalgam had evidence of plasmacytic/lymphocytic inflammation associated with residual silver amalgam in the bone-graft area. The caudoventral portion of the mandible may be used as a donor site for autogenous corticocancellous bone in periodontal surgery of dogs.

Transcutaneous oxygen monitoring for predicting skin viability in dogs

Transcutaneous oxygen (PO2-TC) monitoring is commonly used in human medicine for evaluating skin viability. The application of transcutaneous monitoring for evaluating skin viability in dogs was investigated. The changes in PO2-TC values were measured from 16 avascular skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous oxygen values were serially recorded from the vascular base and avascular apex of each flap for 12 hours after surgery. A single transcutaneous measurement was obtained from each flap base and apex 24 hours after surgery. Serial arterial blood gas analyses were obtained to compare central oxygen values with PO2-TC values. Full-thickness skin biopsy specimens were harvested from the base and apex of each flap 24 hours after surgery. The flaps were observed for 4 days and then excised for histologic examination. A subjective grading scale was used to assess histologic changes. Throughout the 12-hour period and at 24 hours, a statistically significant difference was found between the PO2-TC values for apices and bases of the flaps. The mean PO2-TC for all bases was 90.9 mm of Hg +/- 3.3 SEM, and the mean PO2-TC for all apices was 21.2 mm of Hg +/- 1.8 SEM. The mean regional perfusion index (apex PO2-TC/base PO2-TC) was 0.23 +/- 0.02. The subjective numbers assigned to the biopsy specimens were statistically evaluated by using a paired Student's t test and a Wilcoxon signed-rank test. A significant difference was found between the numbers for the collective bases and apices with both tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of skin viability in dogs, using transcutaneous carbon dioxide and sensor current monitoring

Transcutaneous oxygen monitoring is commonly used in human beings to assess skin viability. Little attention has been directed toward the use of transcutaneous carbon dioxide (PCO2-TC) monitoring for the same purpose. The application of PCO2-TC monitoring for evaluating skin viability in dogs was investigated. The changes in PCO2-TC and local power reference (LPR) values were measured from 16 skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous PCO2 and LPR values were serially recorded from the base and apex of each flap for 12 hours. A single measurement was obtained from each flap base and apex 24 hours after surgery. Arterial blood gas analyses were obtained to compare central PCO2 values with peripheral skin PCO2 values. The flaps were observed for 4 days and then harvested for histologic examination. Full-thickness skin biopsy specimens were obtained 24 hours after surgery and when the flaps were harvested to evaluate the viability of the apex and base of the flaps. A subjective grade was assigned to all skin biopsy specimens during histologic examination. For all measurements, a significant difference was found between the PCO2-TC values for apices and bases of the flaps. The mean PCO2-TC for all bases was 52.66 mm of Hg +/- 2.24 (SEM), and the mean PCO2-TC for all apices was 106.4 mm of Hg +/- 2.44. The regional carbon dioxide index (apex PCO2-TC/base PCO2-TC) was 2.02. A significant difference was not found between the LPR values for bases and apices.(ABSTRACT TRUNCATED AT 250 WORDS)

Escherichia coli bacteremia associated with hypertrophic osteodystrophy in a dog

Escherichia coli bacteremia was detected in a dog that had hypertrophic osteodystrophy. The dog improved after treatment with cephalothin sodium, iv fluid therapy, and cage rest. The cause of hypertrophic dystrophy has not been determined, although an infectious cause has been suggested. Dogs that are suspected of having hypertrophic osteodystrophy should be monitored closely for evidence of septicemia, and the administration of prophylactic antibiotics may be advisable.

Thoracolumbar vertebral osteochondroma in a young dog

Osteosarcoma was diagnosed in a 7-month-old female German Shepherd Dog with hind limb paresis. Radiography revealed a circumscribed calcified mass in the dorsal vertebral lamina at T13-L1 resulting in extradural compression of the spinal cord. Surgical excision of the mass resulted in gradual return to normal neurologic function. Four weeks after surgery, the dog became severely atactic after rolling onto its back. A chip fracture of T13 was identified, and the dog was euthanatized at the owners' request.

Axial pattern flap based on the caudal auricular artery in dogs

An axial pattern flap that was based on the sternocleidomastoideus branches of the caudal auricular artery and vein was developed. Control flaps, which included ligation and division of the caudal auricular artery and vein, were similarly developed on the contralateral aspect of the neck. Mean survival of caudal auricular artery axial pattern flaps (85.2%), compared with control flaps (63.9%), was significantly different (P less than 0.05). On the basis of results of this study, an axial pattern flap based on the sternocleidomastoideus branches of the caudal auricular artery and vein may be a source of skin for reconstructive procedures of the head and neck.

Effect of left hepatic vein ligation on hepatic circulation, function, and microanatomy in dogs

Eighteen healthy dogs were allotted to 3 groups (n = 6 dogs each). All dogs were evaluated at the beginning of the study by complete physical examination; total and differential WBC counts; serum biochemical analysis (alanine transaminase and alkaline phosphatase activities and bilirubin and albumin concentrations); sulfobromophthalein excretion, ammonia tolerance, and glucagon response testing; portal and intraparenchymal pressure determinations; operative mesenteric portography; and histologic assessment of hepatic biopsy specimens. The left hepatic vein was ligated completely in dogs of groups 1 and 2. Group-3 (control) dogs had a ligature placed loosely around the left hepatic vein. Dogs of groups 1 and 3 were reevaluated 24 hours after surgery by use of the aforementioned hematologic and biochemical tests. Group-1 dogs were reevaluated by use of portal and intraparenchymal pressure determinations, jejunal vein portography, and complete necropsy at 48 hours after surgery. At 4 weeks after surgery, dogs of groups 2 and 3 were reevaluated by use of all aforementioned tests. Results indicated transient hepatic congestion, which resolved by the fourth postoperative week. Longstanding effect on hepatic structure, circulation, or function was not found. We concluded that left hepatic vein ligation in clinically normal dogs does not cause severe or permanent liver damage.

Bone healing

Bone is a tissue composed of organic (cells and matrix) and inorganic (mineral) components. When the mechanical strength of bone is exceeded, fracture occurs. Healing progresses through inflammatory, reparative, and remodeling phases similar to other tissues, but, unlike other tissues, bone possesses the unique capability to completely regenerate and return to pre-injury strength. The bone healing process is influenced by many factors, including mechanical stress, biochemical mediators, bioelectric and piezoelectric properties, and neural and endocrine influences. In short, any factor capable of altering the metabolism of osteogenic cells can influence bone healing.

Predicting brain tumor histology: change of effective atomic number with contrast enhancement

Thirty-eight enhancing intracranial neoplasms were evaluated with a dual kilovoltage technique to measure the change of effective atomic number (delta Z), and linear attenuation coefficients with the use of iodinated contrast material. The change of effective atomic number was found to separate intracranial neoplasms into three major groups: gliomas, meningiomas, and metastases. Other parameters, including linear attenuation coefficients and CT numbers, varied from less accurate to inaccurate. The change of effective atomic number with contrast enhancement not only predicted the appropriate histologic group of the neoplasm, but also aided in the differential diagnosis of neoplasms without a characteristic delta Z value.

Patient dosage in computed tomography

The maximum surface dosage in most clinical CT scans seems to range from 2-10 rads/study but much larger dose per study values seem possible with both rotate-translate and rotary geometry designs. The CT scanner type in itself does not significantly reduce doses. Secondary radiation dose values were measured for critical organs and indicate that dosage from secondary radiations may be reduced significantly by external shielding. Dose values in the vicinity of most CT scanners are typically 1-2 mrad/scan at 1 meter at the parameters of a typical clinical scan.

Protocol for a computed tomography scanner performance repository

An argument is presented for organization of a Computed Tomography Scanner Performance Repository. Performance data on CT scanners would be distributed in statistical form to the radiological community. A Protocol is presented for the uniform collection of data. Results of exposure, resolution and visibility measurements made by the authors are presented for the EMI 5005/U, Pfizer 0200 FS and General Electric CT/T scanners.

Effective atomic number and electron density as measured with a computed tomography scanner: computation and correlation with brain tumor histology

The mathematical basis and methodology for determining the effective atomic number and electron density of a tissue are presented. Cranial computed tomography (CT) scanning is performed at two different energy levels, both with and without contrast enhancement. The histology of 15 brain tumors has been correlated with the effective atomic number and electron density of the tumor, with parameters of the linear attenuation coefficient, and with statistical values of the CT numbers. The most useful value in separating gliomas from meningiomas from metastases appears to be the percentage change of effective atomic number following contrast enhancement.

CT determination of parameters for inhomogeneity corrections in radiation therapy of the esophagus

Accurate dose prediction for megavoltage photon therapy of carcinoma of the esophagus requires information on tumor depth, lung thickness, and lung density. The authors found that CT localization of internal and external contours is accurate within +/- 1 mm. Lung density can be measured with an error of less than 0.02 g/cm3 in the range 0.25-1.00 g/cm3. Variance between predicted and measured dosage was less than 3% in all patients and in most RANDO phantom measurements. Accurate radiation therapy planning is possible with CT information from a commercial scanner.

The nonspecificity of absorption coefficients in the differentiation of solid tumors and cystic lesions

Eleven lesions of the brain were analyzed and compared; they had absorption coefficients uniformly at the cerebrospinal fluid (CSF) level following contrast enhancement, and ranged from benign to malignant and solid to cystic. Grossly solid tumors may have absorption coefficients on the CT scan equal to CSF even after contrast enhancement. Absorption coefficients are misleading as histological indicators and in diagnosis; it is impossible to separate cystic from non-cystic, benign from malignant, and neoplastic from non-neoplastic lesions by absorption coefficients alone.

X-ray-transmission computed tomography

The immediate goal of clinically based x-ray-transmission computed tomography (CT) is to provide a measurement of the x-ray linear attenuation coefficient in cross section with the ultimate goal of impacting on patient management and care. To do this with the accuracy needed for clinical goals requires the careful integration of x-ray physics, detector technology, and mathematical reconstruction theory. Performance evaluation and quality assurance are necessary adjuncts to a CT scanning program. A number of investigative studies are underway.

Performance evaluation and quality assurance of computed tomography scanners, with illustrations from the EMI, ACTA, and Delta scanners

Performance evaluation of equipment for computed tomography (CT) involves the integration of: (a) establishing performance criteria; (b) designing and implementing test procedures; and (c) reconciling test results in terms of desired performance. Precision (noise), contrast scale, linearity, accuracy, spatial independence, spatial resolution, artifacts, reproducible performance, and patient exposure are several parameters discussed, as are problems of measurement with regard to non-water bath scanners. Performance and quality control tests for the ACTA, Delta, and EMI scanners are outlined. Guidance for the prospective purchaser of CT equipment is presented as a summary of the ideas discussed.

A survey of the benefits and risks in the practice of radiology

The findings from both animal and human studies on the radiation risk at low doses and low dose rates are far from conclusive, primarily due to statistical limitations. However, to arrive at some estimate of radiation risk, a conservative approach has been taken, and a linear extrapolation of radiation effects from high doses to low doses has been made. Thus, it is assumed that any exposure to radiation carries some risk of somatic or genetic damage and that there is no threshold or safe dose. In medical practice, diagnostic radiological procedures should be performed only if useful clinical information will be derived. In addition, this information should be obtained at the least possible risk to the patient. For mass chest X-rays, mammography, and lung scans, a quantitative determination of benefit to risk is developed. This approach, though possible desirable, is exceedingly difficult to establish for most diagnostic radiological procedures. Thus, good clinical judgement should be employed in radiological practice, just as it should be employed in all aspects of medical practice.