Association of the FGF4L2 retrogene with fibrocartilaginous embolic myelopathy in dogs.

BACKGROUND: Fibrocartilaginous embolic myelopathy (FCE) is a well-documented condition in dogs although rarely reported in chondrodystrophic breeds. Genetic associations have not been defined. OBJECTIVES: Define the association of the chondrodystrophy-associated FGF4L2 retrogene with histopathologically confirmed cases of FCE. ANIMALS: Ninety-eight dogs with a histopathologic diagnosis of FCE. METHODS: Retrospective multicenter study. Dogs were genotyped for the FGF4L2 and FGF4L1 retrogenes using DNA extracted from formalin-fixed, paraffin-embedded tissue. Associations between breed, FCE and retrogene status were investigated with reference to a hospital population and known breed and general population allele frequencies. RESULTS: FGF4L2 genotype was defined in 89 FCE cases. Fibrocartilaginous embolic myelopathy was present in 22 dogs from FGF4L2-segregating breeds with allele frequencies of ≥5%; however, all dogs were wild type. Two Labrador retrievers with FCE carried FGF4L2 alleles. Frequency of the FGF4L2 allele was significantly (P < .001) and negatively associated with FCE relative to predicted hospital-population dogs. FCE was overrepresented in Boxer, Great Dane, Yorkshire Terrier, Bernese Mountain Dog, Miniature Schnauzer, Rottweiler, and Shetland Sheepdog breeds. CONCLUSIONS AND CLINICAL IMPORTANCE: Study data based on genotypically and histopathologically defined cases support the historical observation that FCE is uncommon in chondrodystrophic dog breeds. FGF4 plays an important role in angiogenesis and vascular integrity; anatomical studies comparing chondrodystrophic and non-chondrodystrophic dogs might provide insight into the pathogenesis of FCE.

Temporal and sequence-related variability in diffusion-weighted imaging of presumed cerebrovascular accidents in the dog brain.

Diffusion-weighted MRI (DWI) is often used to guide clinical interpretation of intraparenchymal brain lesions when there is suspicion for a cerebrovascular accident (CVA). Despite widespread evidence that imaging and patient parameters can influence diffusion-weighted measurements, such as apparent diffusion coefficient (ADC), there is little published data on such measurements for naturally occurring CVA in clinical cases in dogs. We describe a series of 22 presumed and confirmed spontaneous canine CVA with known time of clinical onset imaged on a single 3T magnet between 2011 and 2021. Median ADC values of < 1.0x10-3 mm2/s were seen in normal control tissues as well as within CVAs. Absolute and relative ADC values in CVAs were well-correlated (R2 = 0.82). Absolute ADC values < 1.0x10-3 mm2/s prevailed within ischemic CVAs, though there were exceptions, including some lesions of < 5 days age. Some lesions showed reduced absolute but not relative ADC values when compared to matched normal contralateral tissue. CVAs with large hemorrhagic components did not show restricted diffusion. Variation in the DWI sequence used impacted the ADC values obtained. Failure to identify a region of ADC < 1.0x10-3 mm2/s should not exclude CVA from the differential list when clinical suspicion is high.

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.

Subclinical Hypoventilation in Dogs Undergoing Ventral Slot Decompressive Surgery for Cervical Myelopathy Due to Intervertebral Disc Herniation.

The objective of this prospective cohort study was to document the occurrence of post-operative hypoventilation in dogs undergoing decompressive ventral slot or hemilaminectomy for the treatment of intervertebral disc herniation (IVDH). Twenty dogs undergoing ventral slot surgery and 20 dogs undergoing hemilaminectomy surgery for the treatment of IVDH that presented to XX between 2017 and 2020 were enrolled. Dogs were anesthetized using a standard protocol. Blood gas samples were taken at up to 11 time points beginning during anesthetic recovery and continuing for a maximum of 72 h post-operatively. Dogs with cervical lesions that were non-ambulatory before surgery had more evidence of subclinical hypoventilation in the immediate peri-extubation period than dogs with less severe injuries or those undergoing hemilaminectomy surgery. We found no difference in the ventilation status in dogs undergoing cervical or thoracolumbar decompressive surgery for IVDH from 8 to 72 h post-operatively. Other markers of acid-base status indicated that subclinical hypoventilation within the peri-extubation period was transient and self-limiting. There was a moderate positive correlation between sedation scores and estimated PaCO2. These data suggest that dogs with severe cervical spinal cord injuries may be at risk for subclinical hypoventilation in the immediate peri-extubation period. Increased sedation may be correlated with decreased ventilatory status in dogs recovering from decompressive vertebral column surgery.

Relationship between Machine-Learning Image Classification of T2-Weighted Intramedullary Hypointensity on 3 Tesla Magnetic Resonance Imaging and Clinical Outcome in Dogs with Severe Spinal Cord Injury.

Early prognostic information in cases of severe spinal cord injury can aid treatment planning and stratification for clinical trials. Analysis of intraparenchymal signal change on magnetic resonance imaging has been suggested to inform outcome prediction in traumatic spinal cord injury. We hypothesized that intraparenchymal T2-weighted hypointensity would be associated with a lower potential for functional recovery and a higher risk of progressive neurological deterioration in dogs with acute, severe, naturally occurring spinal cord injury. Our objectives were to: 1) demonstrate capacity for machine-learning criteria to identify clinically relevant regions of hypointensity and 2) compare clinical outcomes for cases with and without such regions. A total of 95 dogs with complete spinal cord injury were evaluated. An image classification system, based on Speeded-Up Robust Features (SURF), was trained to recognize individual axial T2-weighted slices that contained hypointensity. The presence of such slices in a given transverse series was correlated with a lower chance of functional recovery (odds ratio [OR], 0.08; confidence interval [CI], 0.02-0.38; p < 10-3) and with a higher risk of neurological deterioration (OR, 0.14; 95% CI, 0.05-0.42; p < 10-3). Identification of intraparenchymal T2-weighted hypointensity in severe, naturally occurring spinal cord injury may be assisted by an image classification tool and is correlated with functional recovery.