Oligodendroglioma with Neuronal Differentiation in Two Boxer Dogs.

Two cases of high-grade glioma comprising sheets of oligodendroglial cells multifocally disrupted by regions of remarkable neuronal differentiation are described. These tumours morphologically resemble 'oligodendroglioma with ganglioglioma-like maturation', a rare tumour of man, but appear to be phenotypically more aggressive. Neuronal markers (synaptophysin, neuron-specific enolase and ßIII-tubulin) effectively highlight neuronal elements within these tumours and could potentially help to further investigate the prevalence and biological significance of neuronal differentiation in canine oligodendroglioma.

Canine intracranial gliomas: relationship between magnetic resonance imaging criteria and tumor type and grade.

Limited information is available to assist in the ante-mortem prediction of tumor type and grade for dogs with primary brain tumors. The objective of the current study was to identify magnetic resonance imaging (MRI) criteria related to the histopathological type and grade of gliomas in dogs. A convenience sample utilizing client-owned dogs (n=31) with gliomas was used. Medical records of dogs with intracranial lesions admitted to two veterinary referral hospitals were reviewed and cases with a complete brain MRI and definitive histopathological diagnosis were retrieved for analysis. Each MRI was independently interpreted by five investigators who were provided with standardized grading instructions and remained blinded to the histopathological diagnosis. Mild to no contrast enhancement, an absence of cystic structures (single or multiple), and a tumor location other than the thalamo-capsular region were independently associated with grade II tumors compared to higher grade tumors. In comparison to oligodendrogliomas, astrocytomas were independently associated with the presence of moderate to extensive peri-tumoral edema, a lack of ventricular distortion, and an isointense or hyper-intense T1W-signal. When clinical and MRI features indicate that a glioma is most likely, certain MRI criteria can be used to inform the level of suspicion for low tumor grade, particularly poor contrast enhancement. Information obtained from the MRI of such dogs can also assist in predicting an astrocytoma or an oligodendroglioma, but no single imaging characteristic allows for a particular tumor type to be ruled out.

Outcome following surgical repair of achilles tendon rupture and comparison between postoperative tibiotarsal immobilization methods in dogs: 28 cases (1997-2004).

Surgical treatment of Achilles tendon rupture in dogs is generally associated with a favourable outcome, although the recovery time to best function is relatively long at 20.2 weeks. Dogs with injuries of less than 21 days duration may have a better functional outcome. When comparing external fixator application to splint or cast management, initial tibiotarsal immobilization method does not significantly affect the complication rate, duration of immobilization, recovery time, or functional outcome.

A comparison of two biomaterial carriers for osteogenic protein-1 (BMP-7) in an ovine critical defect model.

Critical size defects in ovine tibiae, stabilised with intramedullary interlocking nails, were used to assess whether the addition of carboxymethylcellulose to the standard osteogenic protein-1 (OP-1/BMP-7) implant would affect the implant's efficacy for bone regeneration. The biomaterial carriers were a 'putty' carrier of carboxymethylcellulose and bovine-derived type-I collagen (OPP) or the standard with collagen alone (OPC). These two treatments were also compared to "ungrafted" negative controls. Efficacy of regeneration was determined using radiological, biomechanical and histological evaluations after four months of healing. The defects, filled with OPP and OPC, demonstrated radiodense material spanning the defect after one month of healing, with radiographic evidence of recorticalisation and remodelling by two months. The OPP and OPC treatment groups had equivalent structural and material properties that were significantly greater than those in the ungrafted controls. The structural properties of the OPP- and OPC-treated limbs were equivalent to those of the contralateral untreated limb (p > 0.05), yet material properties were inferior (p < 0.05). Histopathology revealed no residual inflammatory response to the biomaterial carriers or OP-1. The OPP- and OPC-treated animals had 60% to 85% lamellar bone within the defect, and less than 25% of the regenerate was composed of fibrous tissue. The defects in the untreated control animals contained less than 40% lamellar bone and more than 60% was fibrous tissue, creating full cortical thickness defects. In our studies carboxymethylcellulose did not adversely affect the capacity of the standard OP-1 implant for regenerating bone.

Assessing the dog as a model for human total hip replacement. Analysis of 38 canine cemented femoral components retrieved at post-mortem.

Post-mortem retrieval of canine, cemented femoral components was analysed to assess the performance of these implants in the dog as a model for human total hip replacement (THR). Mechanical testing and radiological analysis were performed to determine the stability of the implant and the quality of the cement. Thirty-eight implants from 29 dogs were retrieved after time intervals ranging from 0.67 to 11.67 years. The incidence of aseptic loosening was 63.2%, much higher than in human patients (6% in post-mortem studies). Failure of the femoral implants began with debonding at the cement-metal interface, similar to that in implants in man. The incidence of aseptic loosening was much lower in bilateral than in unilateral implants. Significant differences were observed for three different designs of implant. While the dog remains the animal model of choice for THR, results from this study provide insight into interspecies differences in the performance of implants. For example, the performance of THR in dogs should be compared with that in young rather than in elderly human patients.

Diagnosis and treatment of hind limb muscle strain injuries in 22 dogs.

The anamnesis was obtained from the medical records of 22 dogs diagnosed with hind limb muscle strain injury over a four-year period. The signalment, history, diagnostic imaging and clinical findings, treatment and outcome are described. The affected dogs were primarily from large breeds. Although only a few clients reported a specific injury, 11 dogs were admitted for an acute onset of lameness of unknown origin. The hip adductor muscles were affected in 21 dogs, and 11 dogs had previously undergone orthopaedic surgery of the affected limb. The dogs were primarily diagnosed by physical examination, although the diagnosis was confirmed with ultrasound imaging in the two most recent cases. Neither concurrent orthopoedic nor neurological disease was found during the study period in four of 22 dogs, and another three dogs had only mild radiographic coxofemoral osteoarthritis that did not cause any clinical signs during the study period. All of the dogs were treated medically with some combination of rest, physical therapy, methocarbamol, and a non-steroidol anti-inflammatory drug (NSAID). The injury-associated lameness improved, or completely resolved, with conservative, non-surgical therapy in most dogs. Of the 15 dogs available for follow-up (mean 577 days), eight had complete resolution of their clinical signs, two showed significant improvement, and one showed some improvement. Muscle strain injury may be an under-diagnosed cause or contributor to acute hind limb lameness in large breed dogs, either alone or following orthopoedic surgery.

The effect of recombinant human bone morphogenetic protein-2 on femoral reconstruction with an intercalary allograft in a dog model.

This study compared the effect of augmentation of allograft host bone junctions with recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS), autogenous cancellous bone graft (CBG), and a collagen sponge alone in a canine intercalary femoral defect model repaired with a frozen allograft. Outcome assessment included serial radiographs, dual energy X-ray absorptiometry scans, and gait analyses, and mechanical testing and histology of post-mortem specimens. The distal junction healed more quickly and completely with rhBMP-2 than ACS alone based on qualitative radiography and histologic evaluations. The primary tissue in the unhealed gaps in the ACS group was fibrous connective tissue. The proximal allograft host bone junction had complete bone union in the three treatment groups. There was significantly greater new bone callus formation at both junctions with rhBMP-2 than with CBG or ACS alone that resulted in increased bone density around the allograft host bone junctions. All dogs shifted their weight from the treated leg to the contralateral pelvic limb immediately after surgery. Weight bearing forces were redistributed equally between the pelvic limbs at 12 weeks after surgery with rhBMP-2, at 16 weeks after surgery with CBG, and at 24 weeks after surgery with ACS alone. Bending and compressive stiffnesses of the whole treated femora were equal to the contralateral control femora in all treatment groups, whereas torsional rigidities of the whole treated femora for the CBG and ACS groups were significantly less than the control. Both the proximal and distal junctions the treated with rhBMP-2 had torsional stiffnesses and strengths equal to intact control bones. Ultimate failure torques of the proximal junctions of the CBG group and of both junctions of the ACS group were significantly less than the BMP-treated bones. Augmentation of the allograft host bone junctions with rhBMP-2 on an ACS gave results for all parameters measured that equaled or exceeded autogenous graft in this canine intercalary femoral defect model.

Histomorphometric description of allograft bone remodeling and union in a canine segmental femoral defect model: a comparison of rhBMP-2, cancellous bone graft, and absorbable collagen sponge.

The purpose of this study was to determine the effect of recombinant human bone morphogenetic protein type 2 (rhBMP-2) on the histomorphometry of femoral allograft-host bone union and allograft remodeling. A 6 cm mid-diaphyseal femoral defect was created and filled with an allograft stabilized with an interlocking nail in 21 dogs. Dogs were randomly divided into three equal groups and the allograft-host bone junctions and the mid-diaphyses of the allografts were treated with either an absorbable collagen sponge (ACS) loaded with rhBMP-2 (BMP group), an autogenous cancellous bone graft (CBG group), or ACS loaded with buffer solution (ACS group). All dogs received daily tetracycline until sacrifice at 24 weeks to label new bone formation. Histomorphometric analyses on sections of proximal and distal allograft-host bone junctions and the mid-diaphyseal portion of allografts were performed using fluorescent and regular light microscopy. Analyses of the host bone and junctions between allograft and host bone revealed significantly greater new bone formation and larger osteon radii in the BMP group compared to CBG and ACS groups and contralateral intact bone. Porosity in CBG and ACS groups was significantly higher than in the BMP group, which had similar values to intact bone. In transverse sections of allografts, the largest pore diameters were present in the CBG group. Based on all parameters measured, significantly higher bone turnover occurred in the outer cortical area of the allograft in all groups as compared to the inner cortical and mid-cortical areas. New bone formation and osteon radius/osteon width in allografts were similar for all three groups. Higher porosity and larger pore diameters in the CBG and ACS groups suggested higher bone resorption versus formation in these groups compared to the BMP group. The results of this study reveal more balanced allograft bone resorption and bone formation in the BMP group, with greater resorptive activity in the CBG and ACS groups. However, neither rhBMP-2 nor autogenous bone graft increased allograft incorporation when compared to the negative control (ACS group).

Comparison of three methods of gluteal muscle attachment to an allograft/endoprosthetic composite in a canine model.

This study used radiography, gait analysis, gluteal muscle mass, mechanical testing, and qualitative histology to compare three methods of gluteal muscle attachment to an allograft/endoprosthetic composite of the proximal 25% of the femur in an in vivo canine model. The three methods of gluteal muscle attachment were identical to those used clinically in human patients for hip revision and proximal femoral limb salvage: the host gluteal tendon sutured to the allograft tendon (tendon group), the host greater trochanter with intact gluteal tendons secured to the allograft with a cable-grip system (grip group), and periosteally vascularized proximal femoral bone onlay with intact tendons wrapped around the allograft (wrap group). On the basis of radiographs taken every 2 months, the tendon group had more graft fractures than did the grip or wrap group. Radiographic union of the graft-host bone junction occurred more rapidly and there was less graft resorption in the wrap group than in the other two groups. In all dogs, peak vertical ground-reaction forces in the treated limb decreased immediately after surgery and then slowly increased over the length of the study. The dogs in the wrap group regained normal weight-bearing on the treated limb more quickly than did those in the other groups. The constructs in the tendon group were weaker and less stiff immediately after surgery than were those in the other groups or in intact controls. Histologic analysis confirmed that the wrap technique resulted in complete union of the host bone-allograft junction more often than did the other techniques. The wrap method had the best functional outcome after 9 months when an allograft/endoprosthetic composite was used during total hip arthroplasty in this canine model.

A comparison of transdermal fentanyl versus epidural morphine for analgesia in dogs undergoing major orthopedic surgery.

Postoperative analgesia provided by transdermal fentanyl was compared with that provided by epidural morphine in dogs undergoing major orthopedic surgery. Dogs randomly were assigned to receive either a 100 microg per hour transdermal fentanyl patch 24 hours prior to surgery (n=8) or epidural morphine (0.1 mg/kg body weight) administered following induction of anesthesia (n=10). Temperature, heart rate, respiratory rate, and pain score were recorded prior to surgery and zero, six, 18, 30, and 42 hours after surgery. Blood samples were collected from the dogs in the transdermal fentanyl group beginning 24 hours preoperatively to 42 hours postoperatively. Fentanyl concentrations were determined by radioimmunoassay. When all time periods after surgery were combined, dogs in the transdermal fentanyl group were experiencing significantly less pain after surgery than dogs given epidural morphine. The transdermal fentanyl provided analgesia after major orthopedic surgery greater than or equivalent to that of epidural morphine.

In vitro effects of holmium. YAG laser on caprine stifle retinacular restraints.

This study was designed to evaluate the efficacy of the Holmium:YAG laser for performing lateral release and medial joint capsular tightening intracapsularly and to compare the efficacy of the laser versus a scalpel blade for performing a lateral release by performing arthroscopic surgery on 29 caprine patellofemoral joints. Specimens were divided into six treatment groups and treatments consisted of lateral release alone, medial capsular tightening alone, or both treatments, and the effect of each treatment on patellar tracking was evaluated using video analysis of optical markers. Each treatment caused significantly different magnitudes of medial patellar displacement throughout a 75 degrees range of motion: medial tightening followed by lateral release (1.5 +/- 0.10 mm, mean +/- standard error of the mean); lateral release followed by medial tightening (1.1 +/- 0.11 mm); medial tightening alone (0.73 +/- 0.10 mm); lateral release alone (0.36 +/- 0.09 mm); and sham (-0.15 +/- 0.05 mm). There were no significant differences between performing the lateral release using the laser (1.5 +/- 0.10 mm) versus a scalpel (1.4 +/- 0.11 mm). This study shows that lateral release can be performed as effectively with the laser as with a scalpel and that the laser is an effective tool for performing lateral release and medial joint capsular tightening procedures intracapsularly in this caprine model.

Acute, unilateral transverse sinus occlusion during craniectomy in seven dogs with space-occupying intracranial disease.

OBJECTIVE: The purpose of this study was to determine the effect of acute, unilateral transverse sinus occlusion on intracranial pressure (ICP) and postoperative mortality in dogs with structural intracranial disease. STUDY DESIGN: Affected dogs had a single transverse sinus occluded during craniectomy for intracranial mass biopsy or removal. ANIMALS: Seven dogs with space-occupying intracranial disease in the cerebellopontine angle area. METHODS: The ipsilateral transverse sinus was permanently occluded during the surgical approach to the intracranial lesion to increase surgical exposure by allowing a caudal lateral rostrotentorial craniectomy to be combined with a suboccipital craniectomy. In five dogs, intracranial pressure was monitored during surgery using a fiberoptic intracranial pressure monitoring device. RESULTS: Initial ICP varied among dogs, ranging from 7 to 21 mm Hg. Intracranial pressure, however, decreased in all dogs after craniectomy and durotomy (P < .05). No increase in intracranial pressure occurred after transverse sinus occlusion (P = .42). All dogs survived the surgical procedure. CONCLUSIONS: Acute, unilateral transverse sinus occlusion during craniectomy in dogs with space-occupying intracranial lesions did not result in significant increases in ICP or intraoperative mortality. CLINICAL RELEVANCE: Acute, unilateral transverse sinus occlusion during craniectomy can be used to increased surgical exposure to the caudal fossa of the brain without increased risk of increasing ICP.

Cerebral sinus venography in the dog: a new technique.

A new method of performing cerebral sinus venography was developed that opacifies both the ventral and most of the dorsal venous sinus systems. A pediatric angiographic catheter was introduced into the external jugular vein and advanced to the level of the temporal sinus. Iodinated contrast medium was injected manually and radiographs were made. Subtraction radiography was used to visualize vessels filled with contrast medium. Venography was simple and relatively non-invasive and was considered safe. The technique was used to confirm occlusion of the transverse venous sinus in healthy dogs that had undergone radical craniectomies.

The effect of acute, unilateral transverse venous sinus occlusion on intracranial pressure in normal dogs.

Lateral rostrotentorial and caudal suboccipital approaches to the brain were performed on six beagles. Intracranial pressure (ICP) was measured as the two craniectomies were connected by removing the bone of the nuchal crest and occluding the transverse venous sinus. Intracranial pressure remained constant after acute occlusion of the sinus with bone wax and there was no gross evidence of brain edema. All six dogs survived the surgery and five dogs survived for a minimum of 3 months. One dog died acutely during the postoperative period. The exact cause of the cerebellar hemorrhage and infarction found at necropsy in the latter dog was not evident. Anemia occurred in three of the six dogs as a result of intraoperative hemorrhage. All dogs surviving the perioperative period had mild, transient hypermetria and conscious proprioceptive deficits, but were neurologically normal 72 hours after surgery. Results of this study indicate that acute, unilateral transverse sinus occlusion is possible without an increase in ICP. The ability to do this allows access to the rostral aspect of the ipsilateral cerebellum and brain stem.

Intraoperative use of subtraction angiography and an ultrasonic aspirator to improve identification and isolation of an intrahepatic portosystemic shunt in a dog.

Mesenteric portography, using a C-arm fluoroscope equipped with digital subtraction capability, was performed intraoperatively to locate a single, intrahepatic portocaval shunt. An ultrasonic aspirator was used to isolate the shunt, which was ligated completely. Typical portal venous arborization was seen on postligation intraoperative mesenteric portography. Subtraction angiography used intraoperatively and dissection with the ultrasonic aspirator improve the surgeon's ability to localize and isolate intrahepatic portocaval shunts and can reduce surgical time. Film development and patient repositioning and transport, before and after shunt ligation, are not necessary when mesenteric portography is performed intraoperatively, using a C-arm fluoroscope and digital subtraction. Dissection around intrahepatic portocaval shunts is facilitated by the ultrasonic aspirator, which selectively fractures and suctions tissue from around the shunt. Hemorrhage is decreased, because hepatic ductules and small blood vessels are left intact.

Effect of craniectomy/durotomy alone and in combination with hyperventilation, diuretics, and corticosteroids on intracranial pressure in clinically normal dogs.

OBJECTIVE: To determine the effect of craniectomy and durotomy on intracranial pressure (ICP) in clinically normal dogs. DESIGN: Two-part study (experiments A and B) involving craniectomy and durotomy, with and without treatments to lower ICP. ANIMALS: Six (experiment A) and 7 (experiment B) healthy dogs. PROCEDURE: In experiment A, craniectomy was performed in combination with durotomy, diuretic administration, methylprednisolone sodium succinate administration, and hyperventilation, and effect of these manipulations on ICP was determined. In experiment B, dogs had only craniectomy and durotomy without associated ICP-lowering treatments. During both experiments, ICP was monitored throughout the surgical procedure with a fiber optic ICP monitoring device. RESULTS: Intracranial pressure decreased after the combination of craniectomy, durotomy, and other ICP-lowering treatments in dogs of experiment A. Similar magnitude of decrease in ICP was observed in dogs of experiment B after craniectomy and durotomy. CONCLUSIONS: Comparison of these experiments indicate that surgical removal of overlying skull and incision of the dura mater can significantly decrease ICP in clinically normal dogs. CLINICAL RELEVANCE: Craniectomy and durotomy may be useful as an adjunct treatment for increased ICP.

Granulosa cell tumor in an ovariohysterectomized dog.

A granulosa cell tumor was found in a dog with clinical signs of persistent estrus that began 6 years after ovariohysterectomy had been performed. The tumor was diagnosed by use of ultrasonography, provocative testing with human chorionic gonadotropin, and exploratory laparotomy. Hyperestrogenism from functional tumor cells caused bone marrow suppression and endocrine alopecia. Successful treatment included tumor removal, blood transfusions, and antibiotic administration.

Clinical effects of longitudinal division of the corpus callosum in normal dogs.

Longitudinal division of the corpus callosum was performed in six normal beagles to determine surgical morbidity. The corpus callosum was divided sagittally on the midline and the effect on neurological function was determined. Five of six dogs were clinically normal within 14 days or less after surgery. One dog had persistent but improving clinical signs consistent with a forebrain disturbance at 30 days after surgery. Overall, minimal morbidity and no mortality was associated with this surgical procedure. Further study is indicated to determine the efficacy of this surgical treatment for seizure control in dogs with idiopathic epilepsy.

Monoclonal antibodies against pili of serologically distinct Bacteroides nodosus.

Several monoclonal antibodies (McAbs) against pili of Bacteroides nodosus were examined to determine their reactivity with 11 different serotypes. One McAb was identified by enzyme-linked immunosorbent assay (ELISA) analysis that bound to nine of the 11 serotypes and another that bound to the remaining two serotypes tested. In addition, some McAbs demonstrated specificity for a single serotype, while others displayed specificities for up to five other serotypes. Comparison of immunoblot analysis with the ELISA revealed that the former method was not as sensitive in that all McAbs positive by the ELISA, were not positive by immunoblot. Possible explanations of these findings are discussed. There appear to be several antigenic determinants on B. nodosus pili and considerable sharing of these determinants between pili types. The 11 serotypes analyzed by the McAbs in this report are representative of all 20 US serotypes as well as the A-set and D-set categories of Australia. Therefore, the two epitopes recognized by two of the McAbs reported herein encompass all of the currently characterized B. nodosus serotypes and may provide a basis for bivalent vaccines efficacious for all types of B. nodosus induced footrot in sheep.