Randomized clinical trial comparing outcomes after fentanyl or ketamine-dexmedetomidine analgesia in thoracolumbar spinal surgery in dogs.

BACKGROUND: Opioids are widely used for perioperative pain control in dogs undergoing spinal surgery, but alternatives may be required because data suggest that opioids exacerbate inflammation in the injured spinal cord and veterinary access to opioids may become more restricted in the future. OBJECTIVES: To compare recovery of ambulation and other functions between spinal cord-injured dogs receiving peri-operative fentanyl and those receiving a ketamine-dexmedetomidine combination. ANIMALS: A total of 102 client-owned dogs undergoing decompressive surgery for thoracolumbar intervertebral disc herniation. METHODS: Randomized clinical trial. Dogs were randomized 1:1 to fentanyl or a ketamine-dexmedetomidine combination for intra and postoperative analgesia. Primary outcome was time to recovery of ambulation; secondary outcomes were the postoperative Colorado Acute Pain Scale, the short-form Glasgow Composite Measure Pain Scale, time to recovery of voluntary urination and time to unassisted eating. RESULTS: No difference was found in time to recovery of ambulation between groups (adjusted sub-hazard ratio, 0.83; 95% confidence interval [CI], 0.55-1.24; P = .36) or in pain scores (Colorado: χ2  = 14.74; P = .32; Glasgow: χ2  = 6.61; P = .76). Differences in time to recovery of eating and urination were small but favored ketamine-dexmedetomidine (adjusted odds ratios, 3.31; 95% CI, 1.53-7.16; P = .002 and 2.43; 95% CI, 1.00-5.96; P = .05, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: There was no evidence that, at the doses used, fentanyl impaired ambulatory outcome after surgery for thoracolumbar intervertebral disc herniation in dogs. Pain control appeared similar between groups. Secondary outcomes suggested minor benefits associated with ketamine-dexmedetomidine. The ketamine-dexmedetomidine combination appears to be a reasonable alternative to peri-operative opioids.

Transient Megaesophagus Following Coral Snake Envenomation in Three Dogs (2013-2018).

A 12 yr old dachshund, a 7 yr old English springer spaniel, and a 1.5 yr old French bulldog presented following envenomation by a coral snake. Each patient displayed evidence of varying degrees of lower motor neuron dysfunction, but all three developed transient megaesophagus. Two patients developed secondary aspiration pneumonia, with one requiring mechanical ventilation, which the owners declined, resulting in euthanasia. The third developed hypoventilation without aspiration pneumonia, was mechanically ventilated, and was successfully weaned. In the two surviving patients, the megaesophagus resolved by time of discharge. Coral snake envenomation is an uncommon occurrence, and these are the first documented cases of transient megaesophagus secondary to a North American species.

Apparent Ixodes tick paralysis in a cat from North America.

CASE SUMMARY: A 2-year-old castrated male domestic longhair cat presented for acute, diffuse, flaccid paralysis. Thoracic and abdominal radiographs, biochemistry panel and complete blood count were unremarkable. Titers to Toxoplasma gondii, myasthenia gravis radioimmunoassay testing and creatinine kinase levels were within normal limits. The most likely differentials included acute toxicity (coral snake envenomation, organophosphate toxicity), botulism and, less likely, acute polyradiculoneuritis. A thorough physical examination revealed a single engorged tick attached to the ventral neck of the cat, which was later identified as an adult female Ixodes species. Topical fipronil and (S)-methoprene was administered. Over the next 48 h, the cat recovered full motor function and at 5 days post-tick removal the cat had resumed all normal activities. RELEVANCE AND NOVEL INFORMATION: Tick paralysis is considered endemic in Australia by bites from, most commonly, the Ixodes holocyclus tick. However, this phenomenon is rarely reported in the USA. This is the first report of a domestic cat suffering from acute tick paralysis in North America.

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.

Early Blockade of Matrix Metalloproteinases in Spinal-Cord-Injured Dogs Results in a Long-Term Increase in Bladder Compliance.

Spinal cord injury (SCI) is often accompanied by reduced bladder compliance, which contributes to adverse conditions including urinary tract infections and vesicoureteral reflux. Reduced compliance is, in part, attributed to extensive remodeling of the bladder wall, including the extracellular matrix (ECM). Here, we tested the hypothesis that blockade of matrix metalloproteinases (MMPs), known for their ability to remodel the ECM, improves bladder compliance in dogs with SCI. We first evaluated dogs with naturally occurring SCIs resulting from intervertebral disc herniation (IVDH). After characterizing the natural history of urological recovery by cystometry in healthy dogs (n = 10) and dogs with SCIs (n = 20), we conducted a randomized, double-blinded, placebo-controlled clinical trial in dogs with IVDH-associated SCIs to assess the efficacy of the broad-spectrum MMP inhibitor, GM6001, given within 48 h post-injury. The primary outcomes were bladder compliance, as measured by cystometry, and an ordinal gait score (Texas Spinal Cord Injury Score; TSCIS) at day 42 post-SCI. Dogs (n = 93) were randomized to receive either dimethyl sulfoxide (DMSO) or GM6001+DMSO. There were transient, but significantly (p = 0.023) greater, adverse events (31 of 42; 74%) in the GM6001-treated group relative to vehicle controls (22 of 46; 48%). Whereas there were no differences in TSCIS between treatment groups at day 42 (p = 0.9679), bladder compliance was significantly higher in dogs treated with GM6001+DMSO compared to controls (p = 0.0272). Further studies are needed to determine whether this inhibition results from a direct interaction with the bladder wall or indirectly through neural-based mechanisms.

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.

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.

Relationships between cerebrospinal fluid characteristics, injury severity, and functional outcome in dogs with and without intervertebral disk herniation.

BACKGROUND: Cerebrospinal fluid (CSF) is commonly acquired in dogs with intervertebral disk herniation (IVDH) and is a common method to assess inflammatory responses following spinal cord injury (SCI). OBJECTIVES: The purpose of the study was to describe relationships between cisternal CSF characteristics, behavioral measures of SCI, T2- weighted (T2W) hyperintensity on magnetic resonance imaging (MRI), and long-term outcome in dogs with IVDH. Diagnostic accuracy of CSF for differentiating IVDH from other myelopathies was also assessed. METHODS: The retrospective case series included 727 dogs, 443 with thoracolumbar IVDH, 103 with cervical IVDH, and 181 with other spinal cord diseases. Signalment, initial neurologic function, ambulatory function at long-term follow-up, T2W MRI, and CSF variables were recorded for dogs with IVDH. Signalment, etiology, and CSF data were retrieved for dogs with other myelopathies. Associations between CSF predictors, diagnosis, and outcomes were assessed. RESULTS: CSF total nucleated cell count (TNCC) increased with SCI severity (rho -0.256, P < .001) in dogs with IVDH, TNCC was significantly higher in the presence of T2W hyperintensity (P = .001) in dogs with thoracolumbar IVDH, but TNCC, RBC count, microprotein, and percent neutrophils decreased with increasing injury duration (rho -0.253, P < .001; rho -0.269, P < .001; rho -0.141, P = .004, and rho -0.356, P < .001, respectively). CSF characteristics were not accurate for differentiating IVDH from other spinal cord diseases. CONCLUSIONS: In dogs with IVDH, CSF TNCC, RBC count, microprotein, and percent neutrophils are correlated with clinical aspects of SCI such as injury severity and duration, but cannot differentiate IVDH from other etiologies.

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.

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.

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.

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.