Joseph M. Mankin

Prospectively Recorded versus Medical Record‐Derived Spinal Cord Injury Scores in Dogs with Intervertebral Disk Herniation

BACKGROUND Validated spinal cord injury (SCI) scores have been established for veterinary species but are not uniformly used in practice. HYPOTHESIS/OBJECTIVES To determine the level of agreement of SCI scores at the time of admission versus those assigned from reconstructed medical records in a population of dogs with intervertebral disk herniation (IVDH). ANIMALS Eighty-six client-owned dogs with confirmed IVDH. METHODS Retrospective study. Medical records were reviewed for history, physical examination, neurologic examination, and recorded Modified Frankel score (MFS) and Texas spinal cord injury score (TSCIS) at the time of admission. Three raters, all board-certified neurologists, assigned MFS and TSCIS based on digitized abstracted medical records to each patient. These scores were then compared to the recorded score at the time of admission. RESULTS Actual agreement for MFS and TSCIS derived from medical records by the 3 raters compared to prospectively derived MFS and TSCIS was 77.9 and 51.2%, respectively. A kappa value of 0.572 (95% CI 0.450, 0.694; P < .001) and an ICC of 0.533 (95% CI 0.410, 0.646; P < .001) were calculated for MFS scores. A kappa value of 0.100 (95% CI 0.000, 0.222; P = .107), and an ICC of 0.503 (95% CI 0.377, 0.620; P < .001) were calculated for TSCIS scores. CONCLUSIONS AND CLINICAL IMPORTANCE Results showed that SCI scores recorded at the time of admission often do not agree with those retrospectively abstracted from medical records. Agreement was less when using the more complex TSCIS scale and therefore the MFS scale might be more appropriate for use in retrospective studies.

Evaluation of antibodies against feline coronavirus 7b protein for diagnosis of feline infectious peritonitis in cats.

OBJECTIVE To determine whether expression of feline coronavirus (FCoV) 7b protein, as indicated by the presence of specific serum antibodies, consistently correlated with occurrence of feline infectious peritonitis (FIP) in cats. SAMPLE POPULATION 95 serum samples submitted for various diagnostic assays and 20 samples from specific-pathogen-free cats tested as negative control samples. PROCEDURES The 7b gene from a virulent strain of FCoV was cloned into a protein expression vector. The resultant recombinant protein was produced and used in antibody detection assays via western blot analysis of serum samples. Results were compared with those of an immunofluorescence assay (IFA) for FCoV-specific antibody and correlated with health status. RESULTS Healthy IFA-seronegative cats were seronegative for antibodies against the 7b protein. Some healthy cats with detectable FCoV-specific antibodies as determined via IFA were seronegative for antibodies against the 7b protein. Serum from cats with FIP had antibodies against the 7b protein, including cats with negative results via conventional IFA. However, some healthy cats, as well as cats with conditions other than FIP that were seropositive to FCoV via IFA, were also seropositive for the 7b protein. CONCLUSIONS AND CLINICAL RELEVANCE Expression of the 7b protein, as indicated by detection of antibodies against the protein, was found in most FCoV-infected cats. Seropositivity for this protein was not specific for the FCoV virulent biotype or a diagnosis of FIP.

Intracranial extension of retrobulbar blastomycosis (Blastomyces dermatitidis) in a dog

Blastomycosis (Blastomyces dermatitidis) is a fungal disease that is endemic in the southern United States. This case report illustrates the clinical, MRI and histopathologic findings in a dog with invasion of a retrobulbar blastomycotic lesion into the calvarium. A 5-year-old intact female Weimaraner was referred for a 2-month history of change in behavior and recent onset of visual deficits. Magnetic resonance imaging (MRI) examination revealed a large (5.8 × 2.0 × 2.5 cm) mass extending from the left orbit through a circular defect in the left cranioventral aspect of the calvarium caudally to the level of the pituitary fossa and interthalamic adhesion. The mass was heterogeneously iso- to hypointense on T2-W images, slightly hypointense on T1-W images, did not attenuate on fluid attenuated inversion recovery (FLAIR) images, and did not show evidence of susceptibility artifact on T2*-W gradient recalled echo (GRE) images. Vasogenic edema and associated mass effect were noted. The mass showed strong homogeneous contrast enhancement with well-defined margins and had thickening of the adjacent meninges (dural tail sign). Based on MRI findings a malignant neoplastic process was considered most likely and the patient was placed on oral prednisone to decrease peri-tumoral inflammation. The dog initially improved but was euthanized 3 weeks later for worsening clinical signs. Histopathologic assessment of the mass revealed marked pyogranulomatous optic neuritis with intralesional fungal yeasts consistent with blastomycosis (Blastomyces dermatitidis). To our knowledge this is the first report of invasion of a retrobulbar blastomycotic lesion into the calvarium in a dog.

Agreement between T2 and haste sequences in the evaluation of thoracolumbar intervertebral disc disease in dogs.

The purpose of this study was to compare half-Fourier-acquisition single-shot turbo spin-echo (HASTE) and T2-weighted (T2-W) sequences in dogs with thoracolumbar disc extrusion. MRI studies in 60 dogs (767 individual intervertebral disc spaces) were evaluated. Agreement between T2-W and HASTE sequences was assessed for two criteria: presence of an extradural lesion and treatment recommendation. There was moderate agreement between T2-W and HASTE sequences as to presence of an extradural lesion (kappa = 0.575). HASTE was in agreement in 96.1% of the sites where no extradural lesion was identified on T2-W images, but only in 58.1% of the sites where extradural lesions were identified on T2-W images. There was also moderate agreement between T2-W and HASTE sequences as to treatment recommendations (kappa = 0.476). HASTE was in agreement in 98.4% of the sites where a lesion was considered nonsurgical on T2 but only 82.1% of sites a lesion was considered surgical on T2. In 1.0% of sites considered not surgical and in 9.8% of sites considered equivocal based on T2-W images, a surgical lesion was identified on HASTE. Acquisition of a HASTE sequence in addition to conventional sequences may be beneficial in determining the severity of spinal cord compression in some cases when evaluating the canine spine.

Magnetic resonance imaging in cadaver dogs with metallic vertebral implants at 3 Tesla: evaluation of the WARP-turbo spin echo sequence.

Study Design. Laboratory investigation, ex vivo. Objective. Postoperative complications are common after spinal implantation procedures, and magnetic resonance imaging (MRI) would be the ideal modality to image these patients. Unfortunately, the implants cause artifacts that can render MRI nondiagnostic. The WARP-turbo spin echo (TSE) sequence has been developed to mitigate artifacts caused by metal. The objective of this investigation was to evaluate the performance of the WARP-TSE sequence in canine cadaver specimens after implantation with metallic vertebral implants. Summary of Background Data. Magnetic field strength, implant type, and MRI acquisition technique all play a role in the severity of susceptibility artifacts. The WARP-TSE sequence uses increased bandwidth, view angle tilting, and SEMAC (slice-encoding metal artifact correction) to correct for susceptibility artifact. The WARP-TSE technique has outperformed conventional techniques in patients, after total hip arthroplasty. However, published reports of its application in subjects with vertebral column implants are lacking. Methods. Ex vivo anterior stabilization of the atlantoaxial joint was performed on 6 adult small breed (<8 kg) cadaver dogs using stainless steel screws and polymethylmethacrylate. Axial and sagittal T2-weighted and short tau inversion recovery MRI was performed using conventional pulse sequences and WARP-TSE sequences at 3 T. Images were assessed qualitatively and quantitatively. Results. Images made with the WARP-TSE sequence had smaller susceptibility artifacts and superior spinal cord margin depiction. WARP-TSE sequences reduced the length over which susceptibility artifacts caused spinal cord margin depiction interference by 24.9% to 71.5% with scan times of approximately 12 to 16 minutes. Conclusion. The WARP-TSE sequence is a viable option for evaluating the vertebral column after implantation with stainless steel implants. Level of Evidence: N/A

Comparison of two fat-suppressed magnetic resonance imaging pulse sequences to standard t2-weighted images for brain parenchymal contrast and lesion detection in dogs with inflammatory intracranial disease.

T2-weighted (T2w) sequences are commonly relied upon in magnetic resonance imaging protocols for the detection of brain lesions in dogs. Previously, the effect of fluid suppression via fluid-attenuated inversion recovery (FLAIR) has been compared to T2-weighting with mixed results. Short tau inversion recovery (STIR) has been reported to increase the detection of some CNS lesions in people. The purpose of the current study was to evaluate the effect of fat suppression on brain parenchymal contrast resolution and lesion detection in dogs. We compared three sequences: T2w images, STIR, and T2w FLAIR with chemical fat suppression (T2-FLAIR-FS) in dogs with meningoencephalitis. Dogs with meningoencephalitis and dogs with idiopathic epilepsy were retrospectively identified and anonymized. Evaluators recorded the presence or absence of lesions within 12 predetermined brain regions on randomized sequences, viewing and scoring each sequence individually. Additionally, signal-to-noise ratios, contrast-to-noise ratios, and relative contrast (RC) were measured in a reference population. Short tau inversion recovery sequences had the highest RC between gray and white matter. While descriptively more lesions were identified by evaluators on T2-FLAIR-FS images, there was no statistical difference in the relative sensitivity of lesion detection between the sequences. Nor was there a statistical difference in false lesion detection within our reference population. Short tau inversion recovery may be favored for enhanced anatomic contrast depiction in brain imaging. No benefit of the inclusion of a fat-suppressed T2-FLAIR sequence was found.

A comparison of two fat suppressed magnetic resonance imaging pulse sequences to standard T2-weighted images for brain parenchymal contrast and the identification of lesions in dogs with inflammatory intracranial disease

T2-weighted (T2w) sequences are commonly relied upon in magnetic resonance imaging protocols for the detection of brain lesions in dogs. Previously, the effect of fluid suppression via fluid-attenuated inversion recovery (FLAIR) has been compared to T2-weighting with mixed results. Short tau inversion recovery (STIR) has been reported to increase the detection of some CNS lesions in people. The purpose of the current study was to evaluate the effect of fat suppression on brain parenchymal contrast resolution and lesion detection in dogs. We compared three sequences: T2w images, STIR, and T2w FLAIR with chemical fat suppression (T2-FLAIR-FS) in dogs with meningoencephalitis. Dogs with meningoencephalitis and dogs with idiopathic epilepsy were retrospectively identified and anonymized. Evaluators recorded the presence or absence of lesions within 12 predetermined brain regions on randomized sequences, viewing and scoring each sequence individually. Additionally, signal-to-noise ratios, contrast-to-noise ratios, and relative contrast (RC) were measured in a reference population. Short tau inversion recovery sequences had the highest RC between gray and white matter. While descriptively more lesions were identified by evaluators on T2-FLAIR-FS images, there was no statistical difference in the relative sensitivity of lesion detection between the sequences. Nor was there a statistical difference in false lesion detection within our reference population. Short tau inversion recovery may be favored for enhanced anatomic contrast depiction in brain imaging. No benefit of the inclusion of a fat-suppressed T2-FLAIR sequence was found.

Reliability of interpretation of neurologic examination findings for the localization of vestibular dysfunction in dogs

OBJECTIVE To estimate reliability of interpretation of neurologic examination findings for localization of vestibular dysfunction in dogs. DESIGN Cross-sectional study. ANIMALS 496 dogs that underwent MRI of the head for diagnosis of a neurologic problem between September 2011 and September 2015. PROCEDURES Medical records were reviewed and data collected regarding signalment and neurologic examination, MRI, and CSF findings. Independent observers interpreted the findings, and agreement was assessed for a subset of dogs. Distributions of variables were compared between dogs with and without a neurologic findings-based interpretation of vestibular disease. RESULTS 37% (185/496) of dogs had signs of vestibular dysfunction, of which 82% (151/185) had MRI abnormalities. In 73% (110/151) of dogs with MRI abnormalities, lesions involved central vestibular structures, and in 19% (29/151), lesions involved peripheral vestibular structures. On the basis of neurologic findings interpretation, 86% (160/185) of dogs were classified as having central vestibular dysfunction, and 61% (98/160) of these had an MRI-identified central vestibular lesion. Agreement among 3 independent observers was good (κ = 0.72) regarding use of neurologic examination findings to diagnose central versus peripheral vestibular dysfunction and very good (κ = 0.85) regarding use of MRI to diagnose peripheral vestibular lesions. Despite this agreement, only 29% (7/24) of dogs with a consensus clinical interpretation of peripheral vestibular dysfunction had MRI-identified peripheral lesions. CONCLUSIONS AND CLINICAL RELEVANCE Although interobserver agreement was good for distinguishing central from peripheral vestibular dysfunction in dogs through interpretation of neurologic examination findings, this interpretation did not agree with the MRI-based diagnosis.

Evaluation of magnetic resonance imaging for the differentiation of inflammatory, neoplastic, and vascular intradural spinal cord diseases in the dog

Magnetic resonance imaging (MRI) is a common test for dogs with suspected intradural spinal cord lesions, however studies on diagnostic performance for this test are lacking. Objectives of this multi-institutional, retrospective, case-control study were to estimate sensitivity and specificity of MRI for (1) distinguishing between histopathologically confirmed intradural spinal cord disease versus degenerative myelopathy in dogs, (2) categorizing intradural spinal cord diseases as neoplastic, inflammatory, or vascular; and (3) determining tumor type within the etiologic category of neoplasia. Additional aims were to (1) determine whether knowledge of clinical data affects sensitivity and specificity of MRI diagnoses; and (2) report interrater agreement for MRI classification of intradural spinal lesions. Cases were recruited from participating hospital databases over a 7-year period. Three reviewers independently evaluated each MRI study prior to and after provision of clinical information. A total of 87 cases were sampled (17 degenerative myelopathy, 53 neoplasia, nine inflammatory, and eight vascular). Magnetic resonance imaging had excellent (>97.6%) sensitivity for diagnosis of intradural spinal cord lesions but specificity varied before and after provision of clinical data (68.6% vs. 82.4%, P = 0.023). Magnetic resonance imaging had good sensitivity (86.8%) and moderate specificity (64.7-72.5%) for diagnosing neoplasia. Sensitivity was lower for classifying inflammatory lesions but improved with provision of clinical data (48.1% vs. 81.5%, P = 0.015). Magnetic resonance imaging was insensitive for diagnosing vascular lesions (25.0%). Interrater agreement was very good for correctly diagnosing dogs with intradural lesions (ĸ = 0.882-0.833), and good (ĸ = 0.726-0.671) for diagnosing dogs with neoplasia.

Multi-Center Retrospective Evaluation of Screw and Polymethylmethacrylate Constructs for Atlantoaxial Fixation in Dogs

OBJECTIVE To evaluate outcome and adverse events following ventral stabilization of the atlantoaxial (AA) joint in dogs with clinical AA subluxation using screw/polymethymethacrylate (PMMA) constructs in a retrospective, multi-center cohort study. STUDY DESIGN Historical cohort study. ANIMALS 35 client-owned dogs. METHODS Medical records from 3 institutions were reviewed to identify dogs with AA subluxation treated with ventral screw and PMMA constructs. Data on signalment, pre- and postoperative neurologic status, imaging performed, and adverse events were retrieved. Neurologic examination data were abstracted to generate a modified Frankel score at admission, discharge, and re-examination. Telephone interview of owners >180 days postoperative was conducted. RESULTS Thirty-five dogs with AA subluxation treated with ventral screw/PMMA constructs were included. Most dogs were young (median age 1 year), small breed dogs with acute onset of neurologic signs (median duration 22.5 hours). Most dogs were non-ambulatory at the time of admission (median modified Frankel score 3). Adverse events were identified in 15/35 dogs including 9 dogs with major adverse events. Four dogs required a second surgery due to vertebral canal violation (n = 2) or implant failure (n = 2). Re-examination at 4-6 weeks postoperative reported 15/28 dogs with improved neurologic status and 19/28 dogs were ambulatory. Telephone follow-up was available for 23/35 dogs with 23/23 reported as ambulatory (median follow-up 390 days). CONCLUSIONS Ventral application of screw and PMMA constructs for AA subluxation, as described here, is associated with clinical improvement in the majority of dog. Major adverse events are infrequent and the technique is considered relatively safe.