Comparison and optimization of sheep in vivo intervertebral disc injury model.

Background: The current standard of care for intervertebral disc (IVD) herniation, surgical discectomy, does not repair annulus fibrosus (AF) defects, which is partly due to the lack of effective methods to do so and is why new repair strategies are widely investigated and tested preclinically. There is a need to develop a standardized IVD injury model in large animals to enable comparison and interpretation across preclinical study results. The purpose of this study was to compare in vivo IVD injury models in sheep to determine which annulus fibrosus (AF) defect type combined with partial nucleus pulposus (NP) removal would better mimic degenerative human spinal pathologies. Methods: Six skeletally mature sheep were randomly assigned to one of the two observation periods (1 and 3 months) and underwent creation of 3 different AF defect types (slit, cruciate, and box-cut AF defects) in conjunction with 0.1 g NP removal in three lumbar levels using a lateral retroperitoneal surgical approach. The spine was monitored by clinical CT scans pre- and postoperatively, at 2 weeks and euthanasia, and by magnetic resonance imaging (MRI) and histology after euthanasia to determine the severity of degeneration (disc height loss, Pfirrmann grading, semiquantitative histopathology grading). Results: All AF defects led to significant degenerative changes detectable on CT and MR images, produced bulging of disc tissue without disc herniation and led to degenerative and inflammatory histopathological changes. However, AF defects were not equal in terms of disc height loss at 3 months postoperatively; the cruciate and box-cut AF defects showed significantly decreased disc height compared to their preoperative height, with the box-cut defect creating the greatest disc height loss, while the slit AF defect showed restoration of normal preoperative disc height. Conclusions: The tested IVD injury models do not all generate comparable disc degeneration but can be considered suitable IVD injury models to investigate new treatments. Results of the current study clearly indicate that slit AF defect should be avoided if disc height is used as one of the main outcomes; additional confirmatory studies may be warranted to generalize this finding.

Use of cystoscopic-guided laser ablation for treatment of unilateral ureterovesicular stenosis and secondary orthotopic ureterocele in a female dog.

CASE DESCRIPTION A 4-year-old spayed female Beagle was evaluated because of a 2-month history of intermittent pollakiuria, stranguria, dysuria, and abdominal pain. A diagnosis of bacterial cystitis was initially made, but clinical signs persisted despite appropriate antimicrobial treatment, so the dog was referred for further evaluation and treatment. CLINICAL FINDINGS Abdominal ultrasonography revealed a large, thin-walled, cystic structure in the urinary bladder at the level of the expected right ureterovesicular junction that communicated with the uniformly dilated right ureter. Severe right-sided pyelectasia was also detected. A presumptive diagnosis was made of a right-sided orthotopic ureterocele with secondary hydroureter and pyelectasia. TREATMENT AND OUTCOME Cystoscopy revealed a large cystic structure in the region of the right ureterovesicular junction without obvious communication between the ureter and urinary bladder. Portable C-arm fluoroscopy was used to confirm the presence of an intramural orthotopic tract and to measure the diameter of the ureter and renal pelvis via retrograde contrast ureteropyelography. Complete laser ablation of the ureterocele was performed by incising it circumferentially near its base. Clinical signs resolved immediately following the procedure. Six weeks later, the dog remained free of clinical signs and abdominal ultrasonography revealed resolution of hydroureter with persistence of mild right-sided pyelectasia. CLINICAL RELEVANCE Cystoscopic-guided laser ablation of an orthotopic ureterocele secondary to ureterovesicular stenosis was a safe and effective minimally invasive treatment for the dog of this report, resulting in immediate and continued improvement of clinical signs and ultrasonographic changes. Laser ablation should be considered as an alternative to surgery for the treatment of orthotopic ureteroceles in dogs.

Cholecystopexy and Pericardial Pseudocyst Removal in a Dog with a Congenital Peritoneopericardial Diaphragmatic Hernia.

A 4 mo old spayed female golden retriever was presented with a peritoneopericardial diaphragmatic hernia (PPDH) that was diagnosed during neutering. Echocardiography revealed a fluid-filled structure and parts of the liver in the pericardial cavity. Computed tomography confirmed the existence of the PPDH and the herniation of the right medial liver lobe and the gallbladder. Cystic masses were observed in the pericardial and the peritoneal cavities, possibly communicating through the PPDH. A median laparotomy revealed a single lobulated cystic lesion extending into both the pericardial and peritoneal cavities through the PPDH. Because of the nonviable aspect of some parts of the liver parenchyma, the gallbladder was dissected from the fossa, and the central division of the liver was resected. A cholecystopexy was performed on the diaphragm to limit gallbladder mobility. The PPDH was closed in the standard fashion. Histopathology of the cystic structure was compatible with a pericardial pseudocyst. Two months postoperatively, the dog was healthy, and the results of blood biochemistry and abdominal ultrasonography were normal. A pericardial pseudocyst can be associated with a PPDH in young dogs. Moreover, cholecystopexy appears to be a safe and effective method of limiting gallbladder mobility after resection of the central hepatic division.

Congenital urethral stenosis in a male miniature piglet.

A 2-month-old male miniature pig showed progressive abdominal pain, pollakiuria, and stranguria that progressed to complete urinary obstruction. Postmortem examination revealed idiopathic urethral stenosis at the level of the recess, of probable congenital origin. Urinary tract malformations should be included in the differential diagnosis of miniature piglets with urinary disorders.

Sténose urétrale congénitale chez un cochon miniature mâle. Un porcelet miniature mâle âgé de 2 mois a été présenté pour de la douleur abdominale s'aggravant, de la pollakiurie et de la strangurie évoluant jusqu'à une obstruction urinaire complète. L'examen postmortem a révélé une sténose urétrale idiopathique au niveau du récessus, d'origine congénitale probable. Il convient d'inclure les malformations du tractus urinaire dans le diagnostic différentiel des troubles urinaires chez le porcelet miniature.(Traduit par les auteurs).

Computed tomographic characteristics of collateral venous pathways in dogs with caudal vena cava obstruction.

Collateral venous pathways develop in dogs with obstruction or increased blood flow resistance at any level of the caudal vena cava in order to maintain venous drainage to the right atrium. The purpose of this retrospective study was to describe the sites, causes of obstruction, and configurations of venous collateral pathways for a group of dogs with caudal vena cava obstruction. Computed tomography databases from two veterinary hospitals were searched for dogs with a diagnosis of caudal vena cava obstruction and multidetector row computed tomographic angiographic (CTA) scans that included the entire caudal vena cava. Images for each included dog were retrieved and collateral venous pathways were characterized using image postprocessing and a classification system previously reported for humans. A total of nine dogs met inclusion criteria and four major collateral venous pathways were identified: deep (n = 2), portal (n = 2), intermediate (n = 7), and superficial (n = 5). More than one collateral venous pathway was present in 5 dogs. An alternative pathway consisting of renal subcapsular collateral veins, arising mainly from the caudal pole of both kidneys, was found in three dogs. In conclusion, findings indicated that collateral venous pathway patterns similar to those described in humans are also present in dogs with caudal vena cava obstruction. These collateral pathways need to be distinguished from other vascular anomalies in dogs. Postprocessing of multidetector-row CTA images allowed delineation of the course of these complicated venous pathways and may be a helpful adjunct for treatment planning in future cases.

Interobserver agreement and diagnostic accuracy of brain magnetic resonance imaging in dogs.

OBJECTIVE: To evaluate interobserver agreement and diagnostic accuracy of brain MRI in dogs. DESIGN: Evaluation study. ANIMALS: 44 dogs. PROCEDURES: 5 board-certified veterinary radiologists with variable MRI experience interpreted transverse T2-weighted (T2w), T2w fluid-attenuated inversion recovery (FLAIR), and T1-weighted-FLAIR; transverse, sagittal, and dorsal T2w; and T1-weighted-FLAIR postcontrast brain sequences (1.5 T). Several imaging parameters were scored, including the following: lesion (present or absent), lesion characteristics (axial localization, mass effect, edema, hemorrhage, and cavitation), contrast enhancement characteristics, and most likely diagnosis (normal, neoplastic, inflammatory, vascular, metabolic or toxic, or other). Magnetic resonance imaging diagnoses were determined initially without patient information and then repeated, providing history and signalment. For all cases and readers, MRI diagnoses were compared with final diagnoses established with results from histologic examination (when available) or with other pertinent clinical data (CSF analysis, clinical response to treatment, or MRI follow-up). Magnetic resonance scores were compared between examiners with κ statistics. RESULTS: Reading agreement was substantial to almost perfect (0.64 < κ < 0.86) when identifying a brain lesion on MRI; fair to moderate (0.14 < κ < 0.60) when interpreting hemorrhage, edema, and pattern of contrast enhancement; fair to substantial (0.22 < κ < 0.74) for dural tail sign and categorization of margins of enhancement; and moderate to substantial (0.40 < κ < 0.78) for axial localization, presence of mass effect, cavitation, intensity, and distribution of enhancement. Interobserver agreement was moderate to substantial for categories of diagnosis (0.56 < κ < 0.69), and agreement with the final diagnosis was substantial regardless of whether patient information was (0.65 < κ < 0.76) or was not (0.65 < κ < 0.68) provided. CONCLUSIONS AND CLINICAL RELEVANCE: The present study found that whereas some MRI features such as edema and hemorrhage were interpreted less consistently, radiologists were reasonably constant and accurate when providing diagnoses.

Effect of acquisition time and chemical fat suppression on meningeal enhancement on MR imaging in dogs.

Our purpose was to characterize meningeal gadolinium enhancement on magnetic resonance (MR) imaging in dogs with inflammatory and neoplastic diseases, and to assess interobserver variability and the impact of delayed acquisition and chemical fat saturation on its conspicuity. Transverse T1-weighted FLAIR images were acquired prior to, and immediately following gadolinium injection (T0), and at 5 (T5) and 15-20 min delay (TD), with and without fat suppression, in 155 consecutive dogs imaged for suspected brain disease. The agreement on meningeal enhancement was globally substantial (kappa = 0.61) and the likelihood of obtaining a definite diagnosis was significantly increased with the use of fat suppression (P < or = 0.004). Meningeal enhancement was judged definitively present by consensus in 46 of 155 (30%) dogs. Of these, meningeal enhancement was characterized qualitatively and quantitatively in 30 dogs with a clinical diagnosis (18 inflammatory, 11 neoplastic, 1 infarct), and image sequences were compared. Meningeal enhancement was more often diffuse and leptomeningeal in animals with inflammation versus neoplasia (50% vs. 42%, and 69% vs. 48%, respectively), but significant associations were not found. Meningeal thickness and contrast ratio were higher with neoplasia (P < or = 0.02), but results did not vary significantly between series for either group. Yet, images with fat suppression were most useful 50% of the time for definite diagnosis and/or characterization of meningeal enhancement. While delayed image acquisition following gadolinium injection does not improve characterization of meningeal enhancement in dogs, fat suppression is beneficial qualitatively.

Clinical and computed tomography features of secondary renal hyperparathyroidism.

An atypical case of secondary renal hyperparathyroidism was diagnosed in a 9-year-old miniature schnauzer after a skull computed tomography (CT) showed the presence of 2 bilateral and symmetrical soft tissue maxillary masses, and osteopenia of the skull.

Value of fat suppression in gadolinium-enhanced magnetic resonance neuroimaging.

T1-weighted, gadolinium-enhanced magnetic resonance imaging is frequently used to investigate neurologic disease in small animals; however, the abundance of hyperintense adipose tissue adjacent to neural structures, particularly the cranial nerves and spinal cord, can decrease the conspicuity of contrast-enhanced tissues on T1-weighted images. For this reason, chemical fat saturation techniques are used to suppress the signal of adipose tissues, enabling improved depiction of gadolinium-enhanced structures and detection of lesions affecting the nervous system.

Clinical application of Patlak plot CT-GFR in animals with upper urinary tract disease.

Glomerular filtration rate (GFR), an important parameter of renal function, is difficult to assess clinically. Serum creatinine and blood urea nitrogen measurements lack sensitivity, whereas radionuclide determination of GFR is not always available and requires postinjection patient isolation. GFR can be determined using computed tomography (CT), most commonly via Patlak plot analysis. Four adult cats, two adult dogs, and a foal underwent abdominal CT under general anesthesia for various diseases of the upper urinary tract. CT-GFR was measured with a single-slice dynamic acquisition and Patlak plot analysis. In five animals, the total CT-GFR appeared to be below normal, corresponding with mild (two animals) and moderate (two animals) increases of serum creatinine in four. In the two animals with normal or increased CT-GFR, serum creatinine was within the reference values. A significant negative logarithmic relationship was found between CT-GFR and serum creatinine values (P = 0.008; r2 = 0.75). No complications occurred during or following CT-GFR. CT examination provided clinically relevant information in 3/5 patients with possible ureteral obstruction and in 3/3 patients with suspected ureteral calculi. Single-slice dynamic CT-GFR was practical and provided clinically useful information in this small series of patients undergoing CT of the upper urinary tract. There was a significant relationship between CT-GFR and serum creatinine values, which supports the clinical potential of CT-GFR and justifies further investigation of this technique.

Laparoscopic splenectomy for treatment of splenic hemangiosarcoma in a dog.

OBJECTIVE: To report laparoscopic splenectomy in a dog. STUDY DESIGN: Clinical report. ANIMALS: Mixed breed dog (n=1). METHODS: Hemangiosarcoma was diagnosed by ultrasound-guided fine-needle aspiration of a splenic mass in an 11-year-old, 30 kg, mixed breed dog. No metastatic disease was identified during complete staging (chest radiographs, echocardiogram, and abdominal ultrasonography); however, cystic calculi were identified. Laparoscopic splenectomy using Ligasure V was performed through 3 portals and the calculi were removed by laparoscopic-assisted cystoscopy. RESULTS: Total surgical time was 2 hours and for laparoscopic splenectomy, 65 minutes. The celiotomy incision for splenic removal was 7 cm. The dog recovered uneventfully and was ambulatory 2 hours postoperatively. CONCLUSION: Laparoscopy with Ligasure V facilitated successful removal of a spleen with a 3 cm mass. CLINICAL RELEVANCE: Laparoscopic splenectomy in dogs is feasible for removal of a normal-sized spleen with a moderate-sized mass.

Why dissection videos should not replace cadaver prosections in the gross veterinary anatomy curriculum: results from a comparative study.

The goal of our study was to evaluate the impact of a tool intended to eliminate large-animal cadavers from the anatomy laboratory, in view of their prohibitive cost and the logistic difficulties they pose. We sought to determine whether a commented video of the bovine abdominal cavity could effectively replace a prosection of this region. The hypothesis was that students receiving video instruction would achieve lower scores on a post-instructional exam than those benefiting from a commented cadaver prosection. A commented video of the bovine abdominal cavity was compared to a prosection covering identical material. Seventy-five first-year students, having received no prior instruction on the region of interest, were divided into two groups of equivalent knowledge: group A received prosection instruction (N = 38) and group B, video instruction (N = 37). Following instruction, students completed a test on a cadaver, requiring that they correctly match 15 labeled structures with a list of 40 possible answers. Statistical analysis consisted of a repeated-measures linear model with group (A vs. B) as a between-subject factor and time (pre- vs post-test) as a within-subject factor, with significance at p < or = 0.05. Students in group A achieved mean scores of 9.21 +/- 0.31, while those in group B scored 7.65 +/- 0.31. Although both groups significantly improved following instruction, there was a statistically significant difference in the post-instruction scores between groups A and B (p = 0.0007), in favor of the prosection group. The major comment in favor of cadaver prosection pertained to the sensory experience; in favor of video instruction, students stressed accessibility to the pedagogical material for autonomous learning and revision as well as superior viewing compared to the setup adopted for prosections. In conclusion, while our data suggest that cadaver prosections are superior to video demonstrations, it is apparent that students can learn bovine abdominal anatomy by both methods. Future investigations on the subject of alternative teaching methods are warranted.