Comparison of Bending Stiffness between String of Pearls Plate-Bone Substitute Constructs with and without Bending Tees in a Fracture Gap Model.

OBJECTIVE: The aim of this study was to compare the bending properties of String of Pearls plate-bone substitute constructs with and without bending tees in the nodes over a simulated fracture gap. It is hypothesized that the constructs with tees will have higher bending stiffness. STUDY DESIGN: Acetal polymer tubes and 12-hole, 3.5-mm String of Pearls plates were used to create plate-bone substitute constructs simulating stabilization in a bridging fashion over a 45-mm gap. Twenty-four constructs were made with 12 containing tees in the nodes over the fracture gap. Single-cycle load-to-failure 4-point bending was performed in mediolateral and craniocaudal planes. Bending stiffness was compared with a t-test (p < 0.05). RESULTS: All plate-bone substitute constructs had a permanent loss of structural integrity via plastic deformation of the plate. The bending stiffness (mean ± standard deviation) of the craniocaudal group was 59.11 ± 1.98 N/mm with tees and 59.25 ± 1.69 N/mm without tees (p = 0.88). In the mediolateral group, the bending stiffness was 43.17 ± 0.75 N/mm with tees and 41.09 ± 0.91 N/mm without tees (p = 0.0042). CONCLUSION: In 4-point bending, the plate-bone substitute constructs with tees had equivalent bending stiffness in the craniocaudal plane and increased bending stiffness in the mediolateral plane. However, with a small absolute difference in values, the clinical significance is unclear. Future studies for cyclic bending, torsional, and axial compression tests should be performed to further investigate the value of tees in the nodes over a comminuted or gap fracture repaired in a bridging fashion.

The effects of alfaxalone on cardiac and pulmonary vascular size in cats evaluated by thoracic radiography and echocardiography.

Alfaxalone is a neuroactive steroid that modulates the GABAA receptor, which has shown recent widespread use as a sedative and anesthetic agent in cats, especially in patients being screened for cardiovascular disease. This prospective, partially blinded, randomized experimental study aimed to determine if sedation with alfaxalone would alter the appearance of the cardiac silhouette or pulmonary vasculature on thoracic radiographs or echocardiographic indices of cardiac or pulmonary vascular size. Eleven apparently healthy adult cats were recruited from a research colony. Four-view thoracic radiographs and an echocardiogram were performed at baseline and following a 5 mg/kg intramuscular dose of alfaxalone. Vertebral heart score (VHS) and cranial and caudal lobar pulmonary vascular measurements were obtained at both time points by two independent blinded observers, and these were analyzed using two-way ANOVA. The nonblinded echocardiographer obtained echocardiographic measurements at both time points, which were analyzed using a paired t-test or Wilcoxon signed rank test. No significant differences were identified in VHS measurements or echocardiographic parameters between baseline and sedated cats. In healthy cats, alfaxalone does not appear to significantly affect the cardiovascular structures evaluated via thoracic radiography or echocardiography.

Veterinary students' attitudes toward anesthesiology as a specialty.

OBJECTIVE: To identify the perceptions of veterinary students interested in specialization regarding veterinary anesthesiology. STUDY DESIGN: Cross-sectional, multi-institutional, voluntary, anonymous, nonrandomized survey. POPULATION: Veterinary students (303 of 557 total respondents) from 10 veterinary schools. METHODS: Quantitative data were obtained via 5-point Likert scale questions about anesthesia-related topics. Open-ended questions were used to obtain qualitative data. A multivariate logistic regression model assessed the likelihood of choosing a career as an anesthesiologist. Spearman's rank correlation coefficient was used to assess the relationship between 'anesthesia is interesting' and other variables. RESULTS: Of the respondents, 14 (6%) indicated veterinary anesthesia as their chosen specialty. There was a significant positive relationship between 'anesthesia is interesting' and the following variables: age, enjoyment in anesthesia class, belief in the importance of anesthesia for their career, belief in the importance of analgesia for their career, belief that anesthesia and analgesia have a large impact on patient care, interest in pharmacology, interest in physiology, interest in learning technical skills, belief that anesthesiologists are respected by their colleagues and belief that anesthesiologists are an important part of the health care team. More weeks on the anesthesia clinical rotation was positively and significantly associated with increased rotation enjoyment. Enjoyment in the anesthesia class [p = 0.001, Exp(ß) = 2.1, 95% confidence interval (CI): 1.3-3.4] and belief that anesthesia is interesting [p = 0.013, Exp(ß) = 2.6, 95% CI: 1.2-5.4] were predictors that respondents would be more likely to consider a career as a veterinary anesthesiologist. CONCLUSIONS: Those veterinary students with an interest in pharmacology and who enjoyed their anesthesia course were more likely to consider a career as a veterinary anesthesiologist. If students indicated no interest in specializing in veterinary anesthesia, they appreciated the value the specialty brings to animal care and believed that veterinary anesthesiologists are respected by their peers.

Little Brown Bats (Myotis lucifugus) Are Resistant to SARS-CoV-2 Infection.

It has been proposed that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus that spread through human populations as a pandemic originated in Asian bats. There is concern that infected humans could transmit the virus to native North American bats; therefore, the susceptibility of several North American bat species to the pandemic virus has been experimentally assessed. Big brown bats (Eptesicus fuscus) were shown to be resistant to infection by SARS-CoV-2, whereas Mexican free-tailed bats (Tadarida brasiliensis) became infected and orally excreted moderate amounts of virus for up to 18 d postinoculation. Little brown bats (Myotis lucifugus) frequently contact humans, and their populations are threatened over much of their range due to white-nose syndrome, a fungal disease that is continuing to spread across North America. We experimentally challenged little brown bats with SARS-CoV-2 to determine their susceptibility and host potential and whether the virus presents an additional risk to this species. We found that this species was resistant to infection by SARS-CoV-2. These findings provide reassurance to wildlife rehabilitators, biologists, conservation scientists, and the public at large who are concerned with possible transmission of this virus to threatened bat populations.

A retrospective case-control study evaluating systemic blood pressure and heart rate in dogs with brain herniation under general anesthesia.

OBJECTIVE: To examine whether increased systemic arterial blood pressure (ABP) and decreased heart rate (HR) under inhalant anesthesia were suggestive of the Cushing reflex (CR) in dogs with neurological diseases based on magnetic resonance imaging (MRI) findings. STUDY DESIGN: Retrospective case-control study. ANIMALS: A sample of 137 client-owned dogs admitted to two veterinary teaching hospitals for diagnosis and patient care owing to suspected intracranial disease from 2005 to 2020. All dogs underwent general anesthesia for MRI of the brain. METHODS: Based on MRI study reports, dogs were divided into three study groups: group A, dogs with suspected brain herniation; group B, dogs with an abnormal MRI finding but without suspicion of herniation; and group C, dogs with structurally unremarkable brains (control). Initial evaluation by an anesthesiologist resulted in 58 cases selected for further review based on suspicion of having intracranial hypertension, as indicated by ABP and HR changes under anesthesia. Anesthetic records were randomized and independently reviewed by three board-certified anesthesiologists blinded to MRI diagnosis who allocated each dog into one of three groups: 1) likely to have CR; 2) unlikely to have CR; or 3) insufficient data for determination. RESULTS: Of the 58 cases evaluated, nine were considered likely to have CR and 48 were considered unlikely to have CR. In one case, the anesthesiologists were unable to determine whether CR occurred. Of the nine dogs with likely CR, three had an MRI diagnosis of intracranial herniation. The remaining six dogs suspected of CR belonged to the normal brain group. CONCLUSIONS AND CLINICAL RELEVANCE: The ABP and HR changes associated with CR are not reliably associated with brain herniation in dogs undergoing general anesthesia.

Ultrasound-guided and 'blind' sciatic nerve injection techniques: Comparison in rat cadavers.

OBJECTIVE: To compare the success rate and extent of sciatic nerve staining with a bupivacaine-dye solution using two injection techniques: 'blind' or ultrasound-guided approach. STUDY DESIGN: Prospective, experimental, randomized, cadaveric study. ANIMALS: Adult female Wistar rat cadavers [n = 24, mass 352 g (323-374)]. METHODS: Each sciatic nerve was randomly allocated to one of two groups: 'blind' (group B) or ultrasound-guided approach (group US) to injection. Following injection of bupivacaine-dye solution (0.1 mL), gross anatomical dissection was performed to visualize nerve staining, categorizing it as either positive or negative. The length of nerve staining was then measured and visual inspection conducted to identify potential nerve damage. Fisher's exact test was used to compare positive or negative nerve staining, and the Wilcoxon signed rank test used to compare the length of nerve staining between groups. RESULTS: In group B, the bupivacaine-dye solution stained 16/24 sciatic nerves (67% success). In group US, staining was successfully observed in all 24 nerves (100% success, p < 0.004). The length of nerve staining [median (interquartile range)] was 2 (2-3) mm in group B and 5 (4-6) mm in group US (p < 0.001). One sciatic nerve in group B had injectate distributed over 16 mm, suggestive of an intraneural injection. No signs of laceration or nerve damage were visible under 6× magnification in either group. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrasound-guided approach for sciatic nerve injection demonstrated a higher success rate with superior injectate distribution when compared with the 'blind' approach. Ultrasound guidance is recommended over a 'blind' approach for sciatic nerve block in rats when possible.

Serologic Survey of Selected Arthropod-Borne Pathogens in Free-Ranging Snowshoe Hares (Lepus americanus) Captured in Northern Michigan, USA.

Snowshoe hares (Lepus americanus) in the Upper Peninsula (UP) of Michigan, USA, occupy the southern periphery of the species' range and are vulnerable to climate change. In the eastern UP, hares are isolated by the Great Lakes, potentially exacerbating exposure to climate-change-induced habitat alterations. Climate change is also measurably affecting distribution and prevalence of vector-borne pathogens in North America, and increases in disease occurrence and prevalence can be one signal of climate-stressed wildlife populations. We conducted a serosurvey for vector-borne pathogens in snowshoe hares that were captured in the Hiawatha National Forest in the eastern UP of Michigan, USA, 2016-2017. The most commonly detected antibody response was to the mosquito-borne California serogroup snowshoe hare virus (SSHV). Overall, 24 (51%) hares screened positive for SSHV antibodies and of these, 23 (96%) were confirmed positive by plaque reduction neutralization test. We found a positive association between seroprevalence of SSHV and live weight of snowshoe hares. Additionally, we detected a significant effect of ecological land type group on seroprevalence of SSHV, with strong positive support for a group representing areas that tend to support high numbers of hares (i.e., acidic mineral containing soils with cedar, mixed swamp conifers, tamarack and balsam fir as common overstory vegetation). We also detected and confirmed antibodies for Jamestown Canyon virus and Silverwater virus in a single hare each. We did not detect antibodies to other zoonotic vector-borne pathogens, including Lacrosse encephalitis virus, West Nile virus, Borrelia burgdorferi, Powassan virus, and Francisella tularensis. These results provide a baseline for future serological studies of vector-transmitted diseases that may increase climate vulnerability of snowshoe hares in the UP of Michigan, as well as pose a climate-related zoonotic risk.

Comparison of atlantoaxial and lumbosacral cerebrospinal fluid centesis techniques in South American camelids.

BACKGROUND: Iatrogenic blood contamination during cerebrospinal fluid (CSF) centesis is common, which can limit the diagnostic usefulness of the sample. A novel ultrasound-guided CSF collection technique is described in horses, by which CSF is obtained from the atlantoaxial (AA) space. HYPOTHESIS/OBJECTIVES: To compare ultrasound-guided AA centesis with lumbosacral (LS) centesis in South American camelids (SAC). The hypotheses were that AA centesis would yield samples with less blood contamination although being technically more challenging than LS centesis. ANIMALS: Eight clinically healthy adult SAC from a university-owned teaching herd. METHODS: Single-blinded, randomized, 4-way, 4-period crossover study in which 2 veterinarians each performed both centesis techniques on each animal once. Cytological sample analysis was performed, and the technical difficulty of sample acquisition was assessed. RESULTS: The CSF was collected successfully and without complications by either technique during all collection attempts. Aspects of technical difficulty and concentrations of CSF analytes did not vary significantly between techniques. Median total nucleated cell and red blood cell counts were 1/µL and 0.5/µL and 167.5/µL and 155/µL for AA and LS techniques, respectively. The median total protein concentration was 32.9 mg/dL and 38 mg/dL for AA and LS centeses. A median of 1 attempt was necessary for both centesis techniques and the median number of needle repositioning events was 1 for AA and 0 for LS. CONCLUSION AND CLINICAL IMPORTANCE: Depending on clinical circumstances, ultrasound-guided AA centesis appears to be an acceptable alternative to other techniques for collection of CSF from SAC.

Ultrasound-guided sciatic nerve block in Wistar rat cadavers: Relevant anatomy and injection distribution.

OBJECTIVE: To investigate the feasibility of an ultrasound-guided sciatic nerve block by describing the sonoanatomy and comparing the distribution of two volumes of bupivacaine dye solution for nerve staining. STUDY DESIGN: Randomized, experimental, assessor-blinded cadaveric study. ANIMALS: A total of 40 adult female Wistar rat cadavers. METHODS: After studying the sonoanatomy of the sciatic nerve and adjacent structures using a high-resolution linear transducer (19-5 MHz), rat cadavers were randomly divided into two groups that were administered either 0.1 mL (group 0.1) or 0.2 mL (group 0.2) of bupivacaine dye solution per nerve, delivered via an in-plane technique. The extent of nerve staining was subsequently evaluated following dissection. Statistical analysis consisted of assessing data distribution using the Shapiro-Wilk test, followed by paired t-tests for continuous data, Mann-Whitney U test and McNemar's test for categorical data. Statistical significance was defined as p < 0.05. RESULTS: The sciatic nerve was identified bilaterally as a double ellipsoid-shaped image, surrounded by a hyperechoic fascia separating the biceps femoris from the adductor muscle. The hypoechoic structure formed by the bupivacaine dye solution around the nerve was effectively visualized using ultrasound imaging. Sciatic nerve staining was successfully achieved in all pelvic limbs, with dye spread of 4.82 ± 1.55 mm and 5.47 ± 2.18 mm in groups 0.1 and 0.2, respectively (p = 0.128). CONCLUSIONS AND CLINICAL RELEVANCE: This study achieved a detailed understanding of the sonoanatomy of the sciatic nerve and its adjacent structures, highlighting the feasibility of the ultrasound-guided technique for injection in Wistar rats. Furthermore, the results show a comparable distribution of dye solution in both groups. Use of the ultrasound-guided sciatic nerve block technique in rats not only exhibits substantial potential for regional anesthesia but also opens avenues for translational studies.