Anne Bahr

The effect of progressive glomerular disease on megalin-mediated endocytosis in the kidney

BACKGROUND A well-characterized dog model of the X-linked collagen disease Alport syndrome (XLAS) was used to study the effect of progressive glomerular disease on megalin-mediated endocytosis. In XLAS, altered structure and function of the glomerular basement membrane induces a progressive proteinuric nephropathy. METHODS The investigation was performed in male XLAS dogs and age-matched normal male littermates. The urine profile and megalin-mediated endocytosis in the proximal tubule of six healthy and six XLAS dogs were examined at 2, 4, 6, 8 and 10 months of age using SDS-PAGE, immunoblotting and immunohistochemistry. RESULTS Gradually increasing urinary excretion of proteins over time and a reduced content of the same proteins in proximal tubule cells were found. Besides the glomerular component of the proteinuria, a significant tubular component was seen, which is due to a progressive change in the uptake of low-molecular-weight (LMW) ligands by megalin. Furthermore, the protein overload present in the lumen of the proximal tubule exceeds the reabsorption capacity of megalin and the co-receptor cubilin and results in a combined low- and high-molecular-weight (HMW) proteinuria. Also, a shift in the distribution of lysosomes was seen in the XLAS dogs suggesting changes in the lysosomal degradation pattern in response to the altered endocytosis. CONCLUSIONS The present study shows that the increased glomerular permeability and the subsequently altered megalin-mediated and megalin-dependent cubilin-mediated endocytosis lead to a partial LMW proteinuria and partial HMW proteinuria.

Cervical Spinal Locking Plate in Combination with Cortical Ring Allograft for a One Level Fusion in Dogs with Cervical Spondylotic Myelopathy

OBJECTIVE To evaluate use of a surgical technique commonly used in humans for treatment of cervical spondylotic myelopathy (CSM) in dogs. DESIGN Prospective case series. ANIMALS Dogs with CSM (n=10). METHODS Dogs weighing >30 kg that had CSM at 1 vertebral articulation were eligible for inclusion. Dogs had vertebral column distraction/fusion performed using a cortical ring allograft, cancellous autograft, and a spinal locking plate. Dogs were evaluated temporally by repeat neurological examinations and by client perception of postsurgical outcome, determined by telephone interview. RESULTS Nine dogs survived the immediate postoperative period. Seven of 8 dogs had moderate to complete improvement without recurrence (mean follow-up, 2.48 years). The most common postsurgical complications were screw loosening (n=4) and plate shifting (2), neither of which required surgical revision. One dog had pseudoarthrosis that may have negatively impacted outcome. CONCLUSION Treatment of single level CSM in dogs with ring allograft and a spinal locking plate system may lead to successful outcomes. The major problems encountered with included cost of the implants and adjusting the system designed for humans to fit the vertebral column of a dog. CLINICAL RELEVANCE For dogs with CSM at a single level, the use of a spinal locking plate in combination with a cortical ring allograft can be an effective surgical treatment. Costs of the implants as well as anatomic differences in dogs make this type of surgery less appealing.

Vascular Encephalopathy Associated With Bacterial Endocarditis in Four Dogs

Vascular encephalopathy is a commonly encountered clinical complication of infectious endocarditis in humans, but it has been infrequently reported in dogs. A series of four dogs with bacterial endocarditis that subsequently developed acute onset of neurological deficits is described. Clinical signs, diagnostic test results, and outcomes for each case are presented and compared with the human clinical syndrome.

Presumed Immune-Mediated Hemolytic Anemia in a Blue-Crowned Conure (Aratinga acuticaudata)

Abstract Immune-mediated hemolytic anemia occurs infrequently in poultry and is undocumented in parrots. In this study, we describe a blue-crowned conure (Aratinga acuticaudata) with a strongly regenerative anemia, a predominance of round, small erythrocytes (presumed spherocytes), leukopenia followed by leukocytosis, elevated plasma protein, biliverdinuria, and polyuria. Radiography and ultrasonography demonstrated a markedly enlarged spleen. After immunosuppressive treatment with prednisolone, the anemia, abnormal erythrocyte morphology, and biliverdinuria resolved but returned promptly after discontinuation of the therapy. We propose that this conure suffered from an immune-mediated hemolytic anemia.

Presumptive Subdural Empyema in a Dog

A 13 mo old mixed-breed dog was referred for acute lateralized forebrain signs. MRI of the brain demonstrated abnormalities consistent with severe meningitis and subdural empyema secondary to a retrobulbar abscess. The dogs clinical signs improved with antibiotic therapy, and repeat imaging showed resolution of subdural fluid accumulation presumed to be empyema with mild residual meningeal enhancement. Subdural empyema is an infrequent cause of encephalopathy in small animals and usually develops through direct extension of a pericranial infection. This report presents a case of presumptive subdural empyema in a dog that was successfully treated without surgical intervention. MRI is the preferred imaging modality for diagnosis of subdural empyema, and the characteristic imaging features are described.

Effect of computed tomography display window and image plane on diagnostic certainty for characteristics of dysplastic elbow joints in dogs

OBJECTIVE To test the effects of computed tomography (CT) image plane and window settings on diagnostic certainty for CT characteristics associated with dysplastic elbow joints (elbow joint dysplasia) in dogs and to provide optimal display guidelines for these CT characteristics. SAMPLE POPULATION CT images of 50 dysplastic elbow joints from 49 lame dogs and 10 elbow joints from 5 sound dogs. PROCEDURES CT image data were obtained in transverse, sagittal, and dorsal planes. Each plane was examined by use of 3 Hounsfield unit (HU) window settings. Two veterinary radiologists independently evaluated sets of CT images for evidence of 7 CT characteristics. Effect of elbow joint status, image plane, and window settings on diagnostic certainty for these CT characteristics was tested by use of a visual analogue scale. RESULTS Diagnostic certainty for abnormalities of the medial coronoid process (MCP) and radial incisure was highest in the transverse plane, subchondral defects or sclerosis of the trochlea humeri was highest in the dorsal plane, and joint incongruity was highest in the sagittal plane. Certainty for hypoattenuating subchondral defects or fissures was highest at 2,500 or 3,500 HUs, whereas certainty for subchondral sclerosis was highest at 1,500 HUs and lowest at 3,500 HUs. CONCLUSIONS AND CLINICAL RELEVANCE Diagnostic certainty for CT characteristics of elbow joint dysplasia in dogs was affected by image display variables. Diagnostic certainty for altered subchondral bone density was primarily influenced by window settings, whereas structural MCP abnormalities and joint incongruity were influenced most by image plane.

Ectopic Intrathoracic Hepatic Tissue and Accessory Lung Lobe Aplasia in a Dog

A 6 yr old male Yorkshire terrier was presented for an ~6 yr history of progressive cough and dyspnea. Thoracic radiographs revealed a 6 cm diameter mass within the right caudal thorax. Thoracic ultrasound identified an intrathoracic mass ultrasonographically consistent with liver tissue and a chronic diaphragmatic hernia was suspected. Exploratory laparotomy was performed, but no evidence of a diaphragmatic hernia was identified. Thoracic exploration identified abnormal lung parenchyma. The accessory lung lobe was removed using a stapling devise near its base. The consolidated mass had the gross appearance of liver and was histologically identified as ectopic hepatic tissue. Ectopic hepatic tissue, unlike ectopic splenic and pancreatic tissue, is rare and generally has a subdiaphragmatic distribution. This solitary case report demonstrates that ectopic intrathoracic hepatic tissue should be considered a differential diagnosis for a caudal mediastinal mass.

Effects of femur position on radiographic assessment of completeness of femoral head and neck excision in medium to large breed dogs

OBJECTIVE To determine the effect of femur positioning on radiographic assessment of completeness of excision after femoral head and neck excision (FHNE) in medium to large breed dogs. SAMPLE POPULATION 10 femurs from canine cadavers (body weight > 20 kg). PROCEDURE Complete FHNE was performed on 5 canine femurs. Excision consisting of inadequate removal of the medial distal aspect of the femoral neck was performed on the remaining 5 femurs. Each femur was positioned with predetermined amounts of internal and external rotation about the long axis and radiographed. Investigators evaluated a set of 8 radiographic views of each femur. Sensitivity (SE), specificity (SP), positive predictive value, negative predictive value, and completeness of excision assessment accuracy were estimated for each of the femur positions. RESULTS Craniocaudal radiographic views of the femur positioned with external rotation of 15 degrees, 30 degrees, and 45 degrees as a group had the highest SE, SP, and completeness of excision assessment accuracy relative to other radiographic views. The SE, SP, and accuracy of assessment were higher when the degree of external rotation was increased from 15 degrees to 30 degrees or 45 degrees. CONCLUSIONS AND CLINICAL RELEVANCE Craniocaudal radiographic views of the femur positioned in external rotation (15 degrees, 30 degrees, and 45 degrees) improved the ability to detect adequacy of excision relative to standard craniocaudal and lateromedial radiographic views. Evaluation of craniocaudal radiographic views of the femur positioned in external rotation may increase the ability to assess FHNE adequacy in medium- to large-breed dogs.