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.

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–2was 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. © 2000 Cancer Research Campaign

Young, recently weaned pigs were implanted with subcutaneous vascular access ports in experiments designed to determine the relative bioavailability of lead from contaminated soils. In nine experiments, a total of 72 subcutaneous vascular access ports were implanted. Complications were observed in 38.9% of the implanted pigs. Changes in the protocol were implemented in an effort to reduce the rate of complications. The majority of complications were septic processes, including localized infections around the site of the catheter and injection port, hematogenous pulmonary abscessation, endocarditis, and septic arthritis. Staphylococcus aureus, S. hyicus, b-hemolytic Streptococcus species, and Actinomyces pyogenes were cultured from septic processes in these pigs. Our findings suggest that the health of the skin at the time of surgery, the experience of the surgeon, and the immunologic status of the animal influence the risk of septic complications in pigs implanted with subcutaneous vascular access ports.

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.

OBJECTIVETo 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 DESIGNIn 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.RESULTSCrimp-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).CONCLUSIONSThe crimp clamp system provides superior in vitro loop fixation characteristics compared with knot fixation in 27.3 kg test MNL.CLINICAL RELEVANCEBased 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.

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.

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.

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.

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 μg Pb/g of soil. Relative and absolute enteric bioavailabilities of Pb in soil (oral dose groups of 75, 225, and 675 μg 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 μg Pb/kg body wt/day) and an intravenously administered aqueous solution of Pb (100 μg 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 μg 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 μg 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.

Deep digital flexor tendon injuries in dogs are usually the result of a penetrating wound to the planar or plantar surface of the distal extremity. The injury is characterized by hyperextension of one or more digits. The two most commonly used suture repair techniques are the locking-loop pattern and the three-loop pulley pattern. Postoperative management should include a splint or cast designed to hold the digits in flexion for a minimum of 6 weeks. At the time of surgery, the owner should be advised that digital hyperextension may persist ater surgery. The prognosis for canine patients with flexor tendon injury should be good if orthopedic therapy is based on a thorough knowledge of the regional anatomy, early diagnosis, use of atraumatic tendon repair techniques, and incorporation of evolving rehabilitation methods. This article presents two case studies of dogs with injuries of the deep digital flexor tendon and considers the related history, physical examination findings, radiographic findings, surgical therapy, postoperative management and follow-up evaluation.

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.

Pyropheophorbide-a-hexyl ether (HPPH) is a new photosensitizer for use with photodynamic therapy (PDT) that has shown promise in laboratory animals. PDT, using this drug, is being used to treat canine patients afflicted with hemangiopericytoma and oral squamous cell carcinoma (SCC) at the University of Missouri-Columbia College of Veterinary Medicine. To date, 11 dogs with hemangiopericytoma and 5 dogs with oral SCC have been treated using a combination of surgery and PDT. Thus far, there have been no serious complications attributable to the treatment. Two dogs have had recurrences of the hemangiopericytoma and there have been no recurrences of SCC with a median follow time of 5 months. Both recurrent hemangiopericytomas were in patients with large tumors that had previous surgery. This study is ongoing and no conclusions have been reached; however several observations are noted. It appears that PDT using HPPH is safe is dogs, and may decrease the recurrence rate of Hemangiopericytomas. In dogs with oral SCC, the treatment is effective is causing necrosis and sloughing of the tumor tissue, and recurrences have not been noted on follow-ups up to 6 months.

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.

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.

Ultrasonographic examination of the normal canine stifle joint was performed to characterize its normal anatomy, Stifles of four normal adult dogs were imaged in sagittal and transverse planes and each anatomic structure visualized was recorded, Normal anatomic structures consistently seen included the patellar tendon, medial and lateral menisci, the cranial cruciate ligament and femoral condyle cartilage, The caudal cruciate ligament was visualized in two dogs, Collateral ligaments and meniscal ligaments were not visualized, The dogs were then euthanized and each stifle was isolated, Following removal of superficial muscles and skin, each stifle was imaged in a water bath to definitively identify the structures that had previously been visualized on the live dogs, The ultrasonographic appearance of the isolated stifle specimens was similar to that found in live dogs, The results of this study indicate that ultrasound can be used to image the normal anatomy of the canine stifle, The echogenicity of the patellar ligament, cruciate ligaments, menisci and articular cartilage was similar to that previously reported in equine stifles and human knees.

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.