Most students have experience making radiographs prior to veterinary school but have limited radiation safety training.

The use of radiation for the diagnosis of various medical conditions is ubiquitous in veterinary medicine, and manual restraint of a patient during X-ray exposure has become commonplace. Many prospective veterinary students have been involved with radiographs in general practice prior to veterinary school. Their experiences and level of safety training are largely unknown.   This prospective survey study involved two web-based questionnaires that were used to evaluate the experiences, knowledge, and attitudes toward radiation and how these changed following a radiation safety lecture as part of their first-year curriculum. The questionnaires were distributed to 122 first-year veterinary students before and after this lecture. All participating students (100%) had worked in a veterinary hospital prior to admission to veterinary school and 79% were involved in making radiographs; however, only 28% reported receiving radiation safety training. The content of the safety training reported was variable. After the radiation safety lecture, students were more likely to report that the radiation safety training they had received was useful, but fewer students reported feelings of safety when using radiation. Despite most students being involved with radiation in practice, few had received radiation safety training, as hypothesized. Contrary to our second hypothesis, a single lecture did significantly improve knowledge and attitudes in several, but not all, instances. Importantly, once students gained knowledge regarding radiation, they placed more importance on its safe use. These results suggest that in-clinic training of students in radiation safety is insufficient and that lecture-based training is useful for certain concepts.

True Coelomic Hernia and Herniorrhaphy in a Yellow-crowned Amazon Parrot ( Amazona ochrocephala).

An 8-year-old male yellow crowned Amazon parrot ( Amazona ochrocephala) was presented for an 8-month history of intermittent regurgitation, anorexia, and lethargy along with a 3-week history of a soft tissue mass cranial to the vent. Examination revealed a small soft tissue mass, approximately 2 cm in diameter, within the body wall of the coelomic cavity with no discoloration of the surrounding tissue. Full body computed tomography (CT) revealed a defect in the body wall on the ventral coelom from the right paramedian location extending to the right side, which contained intestines. Surgical exploration allowed for reduction of the coelomic hernia, which was encased in fibrous tissue and contained a well-vascularized and motile loop of bowel. The hernia sac was excised before closing the body wall in a simple interrupted pattern. Three months postoperatively, the bird was reported to be doing well at home with no further episodes of regurgitation or anorexia.

Induction dose and recovery quality of propofol and alfaxalone with or without midazolam coinduction followed by total intravenous anesthesia in dogs.

OBJECTIVES: To compare propofol and alfaxalone, with or without midazolam, for induction of anesthesia in fentanyl-sedated dogs, and to assess recovery from total intravenous anesthesia (TIVA). STUDY DESIGN: Prospective, incomplete, Latin-square study. ANIMALS: Ten dogs weighing 24.5 ± 3.1 kg (mean ± standard deviation). METHODS: Dogs were randomly assigned to four treatments: treatment P-M, propofol (1 mg kg-1) and midazolam (0.3 mg kg-1); treatment P-S, propofol and saline; treatment A-M, alfaxalone (0.5 mg kg-1) and midazolam; treatment A-S, alfaxalone and saline, administered intravenously (IV) 10 minutes after fentanyl (7 µg kg-1) IV. Additional propofol or alfaxalone were administered as necessary for endotracheal intubation. TIVA was maintained for 35-55 minutes by infusions of propofol or alfaxalone. Scores were assigned for quality of sedation, induction, extubation and recovery. The drug doses required for intubation and TIVA, times from sedation to end of TIVA, end anesthesia to extubation and to standing were recorded. Analysis included a general linear mixed model with post hoc analysis (p < 0.05). RESULTS: Significant differences were detected in the quality of induction, better in A-M than A-S and P-S, and in P-M than P-S; in total intubation dose, lower in P-M (1.5 mg kg-1) than P-S (2.1 mg kg-1), and A-M (0.62 mg kg-1) than A-S (0.98 mg kg-1); and lower TIVA rate in P-M (268 µg kg-1 minute-1) than P-S (310 µg kg-1 minute-1). TIVA rate was similar in A-M and A-S (83 and 87 µg kg-1 minute-1, respectively). Time to standing was longer after alfaxalone than propofol, but was not influenced by midazolam. CONCLUSIONS AND CLINICAL RELEVANCE: Addition of midazolam reduced the induction doses of propofol and alfaxalone and improved the quality of induction in fentanyl-sedated dogs. The dose rate of propofol for TIVA was decreased.

Retro-orbital and disseminated B-cell lymphoma in a yellow-collared macaw (Primolius auricollis).

A yellow-collared macaw was presented with unilateral left exophthalmia. The complete blood cell count and biochemistry revealed a heterophilic leukocytosis and elevation in liver parameters, respectively. A computed tomography scan showed a contrast-enhancing retrobulbar mass and hepatomegaly. Cytology of the liver was consistent with a round cell tumor, most likely lymphoma. The bird died after 2 months of palliative care. Postmortem examination confirmed a retro-orbital and disseminated B-cell lymphoma.

Lymphome B rétro-orbital et disséminé chez un ara à collier jaune(Primolius auricollis). Un ara à collier jaune a été présenté avec de l'exophtalmie unilatérale gauche. La formule sanguine complète et la biochimie ont révélé une leucocytose hétérophile et une élévation des paramètres hépatiques, respectivement. La tomodensitométrie à l'aide d'une injection de milieu de contraste a montré une masse rétrobulbaire et une hépatomégalie. La cytologie du foie était conforme à une tumeur à cellules rondes, le plus probablement un lymphome. L'oiseau est mort après 2 mois de soins palliatifs. L'examen postmortem a confirmé un lymphome B rétro-orbital et disséminé.(Traduit par Isabelle Vallières).

Ultrasonography detects early laryngeal muscle atrophy in an equine neurectomy model.

INTRODUCTION: A unilateral neurectomy model was used to study the relationship between histologic and ultrasonographic tissue characteristics during muscle atrophy over time. METHODS: This investigation was an in vivo experimental study in an equine model (n = 28). Mean pixel intensity of ultrasonographic images was measured, a muscle appearance grade was assigned weekly, and muscles were harvested from 4 to 32 weeks. Minimum fiber diameter, fiber density per unit area, percent collagen, percent fat, and fiber type profile were measured from muscle cryosections and correlated with the ultrasonographic parameters. RESULTS: A significant relationship was identified between collagen content, minimum fiber diameter, and ultrasonographic muscle appearance by as early as 8 weeks. There was no apparent association between fat content of muscle and the ultrasonographic appearance of atrophy before 28 weeks. CONCLUSIONS: Early muscle atrophy before fatty infiltration is detectable with ultrasound. The effect of muscle collagen content on echointensity may be mediated by reduced fiber diameter.

DISTRIBUTION AND SHORT- AND LONG-TERM EFFECTS OF INJECTED GELIFIED ETHANOL INTO THE LUMBOSACRAL INTERVERTEBRAL DISC IN HEALTHY DOGS.

Radiopaque gelified ethanol preparation has been described as a useful agent for treatment of humans with intervertebral disc protrusion. The material is injected into the nucleus pulposus under image guidance with intention to cause the protruded disc material to recede. Because treatment options for dogs with chronic protrusions are limited, new and minimally invasive treatments are desirable. The aim of this experimental, descriptive, prospective study was to assess the feasibility and safety of percutaneous injection of gelified ethanol into the lumbosacral intervertebral disc of dogs. Lumbosacral intervertebral discs of normal dogs (n = 9) were imaged with magnetic resonance imaging and then injected with gelified ethanol using image guidance. The accuracy of gelified ethanol placement in the nucleus pulposus and presence of leakage of the injected material were documented. Postinjection computed tomography (CT) findings (n = 9), short-term (n = 9) and long-term (n = 4) follow-up magnetic resonance imaging and CT findings were compared to document the distribution of the injected preparation and identify effects on adjacent tissues. Percutaneous injection of the intervertebral disc was successful in delivering radiopaque gelified ethanol to the nucleus pulposus in all dogs. Leakage of the injected material into the vertebral canal was present in three dogs immediately following injection and in another additional dog at 1 year following injection. All dogs tolerated the injection well and had no clinical adverse reactions within the study period. Findings indicated that injection of the nucleus pulposus of healthy dogs was well tolerated, even in the presence of mild leakage of material from the intervertebral disc.

3D-Ultrasonography for evaluation of facial muscles in patients with chronic facial palsy or defective healing: a pilot study.

BACKGROUND: While standardized methods are established to examine the pathway from motorcortex to the peripheral nerve in patients with facial palsy, a reliable method to evaluate the facial muscles in patients with long-term palsy for therapy planning is lacking. METHODS: A 3D ultrasonographic (US) acquisition system driven by a motorized linear mover combined with conventional US probe was used to acquire 3D data sets of several facial muscles on both sides of the face in a healthy subject and seven patients with different types of unilateral degenerative facial nerve lesions. RESULTS: The US results were correlated to the duration of palsy and the electromyography results. Consistent 3D US based volumetry through bilateral comparison was feasible for parts of the frontalis muscle, orbicularis oculi muscle, depressor anguli oris muscle, depressor labii inferioris muscle, and mentalis muscle. With the exception of the frontal muscle, the facial muscles volumes were much smaller on the palsy side (minimum: 3% for the depressor labii inferior muscle) than on the healthy side in patients with severe facial nerve lesion. In contrast, the frontal muscles did not show a side difference. In the two patients with defective healing after spontaneous regeneration a decrease in muscle volume was not seen. Synkinesis and hyperkinesis was even more correlated to muscle hypertrophy on the palsy compared with the healthy side. CONCLUSION: 3D ultrasonography seems to be a promising tool for regional and quantitative evaluation of facial muscles in patients with facial palsy receiving a facial reconstructive surgery or conservative treatment.

Chronic liver lobe torsion in a cat.

A 13 yr old castrated male blue British shorthair with a 3 mo history of vomiting was diagnosed with a left lateral liver lobe mass following abdominal ultrasonography. At the time of celiotomy, liver lobe torsion (LLT) of the left lateral lobe was also present. Histopathologic evaluation of the liver mass and associated lobe revealed extensive necrosis secondary to chronic torsion. This is the second reported case of LLT in a cat. Both cases were associated with liver masses. The cat presented in this case remained clinically normal 8 mo postoperatively following lobectomy of the affected lobe.

Imaging diagnosis--temporomandibular joint dysplasia in a Basset Hound.

A 5-month-old intact male Basset Hound presented for evaluation of pain and crepitation during manipulation of the temporomandibular joint, worse on the right side. A computed tomography (CT) scan of the head was performed. The CT images demonstrated the osseous features of temporomandibular joint dysplasia and facilitated a 3D reconstruction, which allowed better visualization of the dysplastic features. The patient responded to conservative management with a tape muzzle with no recurrence reported by the owner 6 months after presentation.

Comparison between computed tomography, fluoroscopy, and ultrasonography for guiding percutaneous injection of the canine intervertebral disc.

A minimally invasive method for delivering injectable therapeutic agents would be desirable for the treatment of intervertebral disc disease in dogs. The purpose of this study was to compare computed tomography (CT), ultrasonography (US), and fluoroscopy modalities for guiding percutaneous injection into canine intervertebral discs. Intervertebral discs of 14 dog cadavers were injected with a gelified ethanol therapeutic agent. Successful injectate placement and injectate leakage were determined based on necropsy inspection of discs. Injection into the nucleus pulposus was successful in 55 of 78 (71%) of all injected discs. Injections guided using CT and fluoroscopy were significantly more successful than US-guided injections. Odds of successful injection without leakage were greater for CT vs. US (P = 0.0026) but there was no significant difference between CT and fluoroscopy (P = 0.0620). Injection success rates did not differ among vertebral sites or dog cadavers of varying weights. Forty-nine (63%) of injection sites had injectate leakage outside the disc and 10 of these involved structures within the vertebral canal. The highest rate of injection success with the least amount of leakage was achieved with CT guidance. Findings indicated that CT, fluoroscopy, and US are feasible modalities for guiding percutaneous injection of a gelified ethanol therapeutic agent into the canine intervertebral disc, with moderate to high success rates for different regions of the spine. However, a moderately high rate of injectate leakage occurred outside of the disc and this should be taken into consideration for future safety and efficacy studies.

Quantitative ultrasonography of facial muscles.

INTRODUCTION: There is no standardized method for examination of facial muscles with ultrasound. The purpose of this study was to identify those facial muscles accessible for reliable identification and to provide reference data. METHODS: In healthy subjects all facial muscles were screened for visibility, separation from adjacent muscles, and reliability of landmarks. Bilateral scans of reliable muscles were performed in 40 adult volunteers. RESULTS: Six facial muscles were clearly demarcated with ultrasound. These were: frontalis, orbicularis oculi, orbicularis oris, depressor anguli oris, depressor labii inferioris, and mentalis muscles. Cross-sectional area and muscle thickness showed gender differences and were independently related to age for some muscles. A significant left-right side difference was only seen for the orbicularis oculi muscle in women. CONCLUSIONS: These data demonstrate the usefulness of ultrasonography to assess facial muscles and provide reference values that can be applied in the clinical setting.

Experimental transmission of enzootic nasal adenocarcinoma in sheep.

Enzootic nasal adenocarcinoma (ENA) is a contagious neoplasm of the secretory epithelial cells of the nasal mucosa of sheep and goats. It is associated with the betaretrovirus, enzootic nasal tumor virus (ENTV), but a causative relationship has yet to be demonstrated. In this study, 14-day-old lambs were experimentally infected via nebulization with cell-free tumor filtrates derived from naturally occurring cases of ENA. At 12 weeks post-infection (wpi), one of the five infected lambs developed clinical signs, including continuous nasal discharge and open mouth breathing, and was euthanized. Necropsy revealed the presence of a large bilateral tumor occupying the nasal cavity. At 45 wpi, when the study was terminated, none of the remaining infected sheep showed evidence of tumors either by computed tomography or post-mortem examination. ENTV-1 proviral DNA was detected in the nose, lung, spleen, liver and kidney of the animal with experimentally induced ENA, however there was no evidence of viral protein expression in tissues other than the nose. Density gradient analysis of virus particles purified from the experimentally induced nasal tumor revealed a peak reverse transcriptase (RT) activity at a buoyant density of 1.22 g/mL which was higher than the 1.18 g/mL density of peak RT activity of virus purified from naturally induced ENA. While the 1.22 g/mL fraction contained primarily immature unprocessed virus particles, mature virus particles with a similar morphology to naturally occurring ENA could be identified by electron microscopy. Full-length sequence analysis of the ENTV-1 genome from the experimentally induced tumor revealed very few nucleotide changes relative to the original inoculum with only one conservative amino acid change. Taken together, these results demonstrate that ENTV-1 is associated with transmissible ENA in sheep and that under experimental conditions, lethal tumors are capable of developing in as little as 12 wpi demonstrating the acutely oncogenic nature of this ovine betaretrovirus.

Ultrasound-guided percutaneous antegrade hydropropulsion to relieve ureteral obstruction in a pet guinea pig (Cavia porcellus).

Severe hydroureter and hydronephrosis secondary to ureteral obstruction by calculus were present in a guinea pig. A palliative ultrasound-guided percutaneous antegrade hydropropulsion was performed under general anesthesia to relieve the ureteral obstruction and the associated clinical signs. We describe the technique and the considerations for its potential application in similar cases.

Hydropropulsion antérograde percutanée guidée par échographie pour soulager l'obstruction urétérale d'un cobaye de compagnie(Cavia porcellus). Une urétérohydrose et une hydronéphose graves secondaires à une obstruction urétérale causée par des calculs étaient présentes chez un cobaye. Une hydropropulsion antérograde percutanée guidée par échographie a été réalisée sous anesthésie générale pour soulager l'obstruction urétérale et les signes cliniques connexes. Nous décrivons la technique et les considérations pour son application potentielle dans des cas semblables.(Traduit par Isabelle Vallières).

The Ontario Veterinary College Hip Certification Program -- assessing inter- and intra-observer repeatability and comparison of findings to those of the Orthopedic Foundation for Animals.

In Canada, the Ontario Veterinary College (OVC) has offered radiographic screening for hip dysplasia for many years, but there are other options for this service including the Orthopedic Foundation for Animals (OFA). There are some differences between the OFA and the OVC methods, and this study compares the OVC and OFA hip certification results in 37 dogs. There was good agreement between the two programs but in some instances there was a difference in the pass/fail status of a dog. Neither the OFA nor the OVC was more likely to fail or pass a given dog. The repeatability of the OVC results was assessed by both inter- and intra-observer comparisons in 100 dogs. There was at least 86% agreement among and within radiologists, but in 5 cases the disagreement resulted in a difference in the pass/fail status of the dog. These results illustrate the inherent variation in radiographic hip evaluation and highlight the importance of consensus grading practices to improve the accuracy of hip evaluation.

Programme de certification des hanches de l'Ontario Veterinary College ­ Évaluation de la reproductibilité inter- et intra-observateur et comparaison des résultats à ceux de l'Orthopedic Foundation for Animals. Au Canada, l'Ontario Veterinary College (OVC) offre le dépistage radiographique de la dysplasie de la hanche depuis de nombreuses années, mais il y a d'autres options pour ce service, incluant l'Orthopedic Foundation for Animals (OFA). Il y a certaines différences entre les méthodes de l'OFA et de l'OVC et cette étude compare les résultats de certification de la hanche de l'OVC et de l'OFA chez 37 chiens. Il y avait une bonne concordance entre les deux programmes, mais dans certains cas, il y avait une différence au niveau du statut d'échec-réussite d'un chien. Ni l'OFA ni l'OVC ne présentait une probabilité accrue de donner un résultat d'échec ou de réussite à un chien particulier. La reproductibilité des résultats de l'OVC a été évaluée par des comparaisons inter- et intra-observateur chez 100 chiens. Il y avait au moins 86 % de concordance entre et parmi les radiologistes, mais dans 5 cas, la discordance s'est traduite par une différence du statut de réussite et d'échec chez le chien. Les résultats illustrent la variation inhérente à l'évaluation radiographique de la hanche et souligne l'importance de pratiques de classification par consensus afin d'améliorer l'exactitude de l'évaluation de la hanche.(Traduit par Isabelle Vallières).

Voices from Service Providers Who Supported Young Caregivers throughout the COVID-19 Pandemic in the Canadian Context.

This empirical research is part of a larger project beginning in 2020 and ongoing until 2023, exploring the impact of the COVID-19 pandemic on young caregivers aged 5-25 years and their families in Canada. This qualitative research utilizes the social determinants of health as a conceptual framework and a collective case study design to emphasize the voices and experiences of service providers (professionals offering services to young caregiver clients) during the COVID-19 pandemic, and exploring their perspectives on the impact of the pandemic on young caregivers and their families. The central research question guiding this study was "How do service providers (professionals) working with young caregiver clients in Canada describe the impacts of the pandemic on themselves, their professional praxis, and on their young caregiver clients?" The aim of this study was to develop a deeper understanding of the impact of the pandemic on young caregivers in Canada, from the perspectives of service providers, as well as to understand the experiences of service providers in their own voices. Data were collected from service providers working within three (3) different organizations offering programs and services to young caregiver clients in Ontario, Canada. In total, six (6) individual interviews were conducted with service providers who were directors/program managers, and four (4) group interviews were conducted with thirteen (13) service providers who were frontline staff members who worked directly with young caregivers and their families. In total, nineteen (n = 19) unique service providers participated in this study. Our findings point to two primary overarching themes, namely (1) service providers' responses to the pandemic and (2) observations by service providers about the impacts of the pandemic on young caregivers, and a secondary theme, (3) positive outcomes from the COVID-19 pandemic on young caregivers, that emerged through the analysis. The pandemic led to increased demands for services by young caregiver clients. Service providers were required to adapt their service delivery methods in order to comply with public health guidelines. They shared how their work impacted their mental health as they struggled to maintain personal and professional boundaries while working from home during the pandemic. Importantly, service providers identified similar, simultaneous, and co-occurring impacts of the pandemic between their young caregiver clients, including isolation, difficulties in navigating online spaces, and challenges in navigating boundaries while working from home with family members.

The Impact of Public Health Restrictions on Young Caregivers and How They Navigated a Pandemic: Baseline Interviews from a Longitudinal Study Conducted in Ontario, Canada.

This qualitative research study is a part of a larger research project exploring the experiences of young caregivers aged 5-26 years and their families navigating the COVID-19 pandemic between 2020 to 2023. Data were collected from 14 young caregivers who participated in baseline interviews. The central research question guiding this study: What was, is, and will be the impact of changing public health restrictions on young caregivers and their families during the pandemic and pandemic recovery? Seven themes emerged through analysis: (1) Navigating Care During the Height of Public Health Restrictions, (2) Neighbourhood and Built Environment During the Pandemic, (3) Perceptions Towards COVID-19 and Public Health Restrictions/Efforts, (4) The Impact of Public Health Restrictions on Relationships, (5) Mental Health Challenges of Being a Young Caregiver During a Pandemic, (6) Navigating Formal Services and Supports, and (7) Recommendations from Young Caregivers. The findings from this empirical research suggest that young caregivers found it easier to navigate their caregiving responsibilities when public health restrictions and work-from-home mandates were initially implemented; however, this later changed due to challenges in finding respite from caregiving, maintaining social connections with friends, creating personal space at home, and finding adequate replacements for programs once offered in person.

Comparison of three techniques for paravertebral brachial plexus blockade in dogs.

OBJECTIVE: To compare success and complication rates, based on staining of nerves and other structures, among three techniques of paravertebral brachial plexus blockade (PBPB) in dogs. STUDY DESIGN: Prospective randomized design. ANIMALS: A total of 68 thoracic limbs from 34 dogs. METHODS: Limbs were randomly assigned to blind (BL) (n = 24), nerve stimulator-guided (NS) (n = 21) or ultrasound-guided (US) (n = 23) technique. Injections were made with 0.3 mL kg(-1) of lidocaine mixed with new methylene blue. Time to perform each block and current used during NS technique were recorded. Dogs were anesthetized during the blocks and euthanized once completed. Dissections were performed to evaluate staining of nerves, spinal cord, mediastinum, pleura and vessels. An anova and Tukey adjustment for time, logistic regression for association between current and nerve staining and a generalized linear mixed model for staining of different structures were used. Significance was considered when p ≤ 0.05. RESULTS: The median (range) number of nerves stained was 2 (0-4) with BL, 1 (0-3) with NS and 1 (0-4) with US guided technique. No significant differences in staining of C6, C8 and T1 or other structures were found among techniques. Nerve C7 was more likely to be stained by BL (p = 0.05). Time to perform the blocks was significantly different among techniques, with mean ± SD duration in minutes of 3.6 ± 1.8 with BL, 6.3 ± 2.7 with US and 12.2 ± 5 with NS. The most common complication was staining of the spinal cord (29%, 38% and 39% with BL, NS and US, respectively). CONCLUSIONS: Success rates were low and complication rates were relatively high, based on staining, with the three techniques. CLINICAL RELEVANCE: The use of more advanced techniques for PBPB in dogs is not justified according to this study. Clinical significance of the complications encountered in this study should be evaluated.

Unfolding What Self-Compassion Means in Young Carers' Lives.

Young carers (YCs) are children and youth who provide caregiving for family members who may experience an illness, disability, addiction, language barriers, and/or age-related needs. Many of them show compassion towards others and continue to put their family members' needs before their own. They also report having no time for other activities or for themselves due to the caregiving role. Self-compassion might allow YCs to be kind to themselves, be mindful of their emotions, and understand that others, like them, go through similar experiences. While the relationship between outward and inward compassion has been examined in past research, studies have yet to determine YCs' self-compassion level in the context of providing care for others. The purpose of this qualitative study was to gain a better understanding of what compassion and self-compassion meant for YCs and whether they saw themselves as self-carers in addition to being caregivers. Six focus groups with YCs ages 12 to 18 years (n = 33) were conducted. Eight boys and 26 girls were divided into younger and older focus groups. A constant comparison analysis yielded three major themes: characteristics of compassion, self-compassion in YCs, and supports for self-compassion. Overall, YCs showed continual compassion for their loved ones, but despite understanding the value of self-care and self-compassion in one's lives, very few YCs displayed self-compassion. Some reported conflicts and tensions within them and between them and their family member(s). The role of parents and YC programs were addressed as a possibility for supporting self-compassion.

Effects of hypercapnia, hypocapnia, and hyperoxemia on brain morphometrics determined by use of T1-weighted magnetic resonance imaging in isoflurane-anesthetized dogs.

OBJECTIVE: To evaluate the effects of various combinations of PaCO2 and PaO2 values on brain morphometrics. ANIMALS: 6 healthy adult dogs. PROCEDURES: A modified Latin square design for randomization was used. Dogs were anesthetized with propofol (6 to 8 mg/kg, IV), and anesthesia was maintained with isoflurane (1.7%) and atracurium (0.2 mg/kg, IV, q 30 min). Three targeted values of PaCO2 (20, 40, and 80 mm Hg) and 2 values of PaO2 (100 and 500 mm Hg) were achieved in each dog, yielding 6 combinations during a single magnetic resonance (MR) imaging session. When the endpoints were reached, dogs were given at least 5 minutes for physiologic variables to stabilize before T1-weighted MR images were obtained. Total brain volume (TBV) and lateral ventricular volume (LVV) were calculated from manually drawn contours of areas of interest by use of a software program, with each dog serving as its own control animal. Three blinded investigators subjectively evaluated the lateral ventricular size (LVS) and the cerebral sulci width (CSW). Brain morphometric values were compared among the target blood gas states. RESULTS: No significant differences in TBV were found among target states. The LVV was significantly greater during hypocapnia, compared with hypercapnia at the same PaO2 value. With regard to the subjective evaluations, there were no significant differences among evaluators or among combinations of PaO2 and PaCO2 values. CONCLUSIONS AND CLINICAL RELEVANCE: The changes observed in LVV during hypocapnia and hypercapnia may serve as a potential confounding factor when neuromorphometric evaluations are performed in anesthetized dogs.

On the association between sexual attraction and adolescent risk behavior involvement: Examining mediation and moderation.

On the basis of a large-scale survey of high-school youth, the authors compared adolescents reporting exclusively heterosexual, mostly heterosexual, bisexual, and predominately same-sex attraction based on high-risk involvement across a range of risk behaviors. Bisexual and same-sex attracted groups were characterized by heightened high-risk involvement relative to the other two groups. Mediation analysis was used to determine whether these group disparities were explained by a set of normative predictive factors spanning multiple life domains. Differences among a combined exclusively/mostly heterosexual attraction group and both the bisexual and same-sex attraction groups were attenuated (66% and 50%, respectively) after incorporating the hypothesized intervening predictive factors, providing evidence of partial mediation. Primary mediators included intrapersonal (attitudes toward risk-taking; academic orientation), interpersonal (peer victimization; parental relationships; unstructured activities), and environmental (substance availability) factors. Mediation results were consistent across participant age and sex. Implications, limitations, and directions for future research are discussed.