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  • Author or Editor: Richard F. Larson x
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Abstract

Objective—To evaluate the effect of infection with bovine respiratory syncytial virus (BRSV) on clearance of inhaled antigens from the lungs of calves.

Animals—Eleven 6- to 8-week-old Holstein bull calves.

Procedures—Aerosolized 99mtechnetium (99mTc)-labeled diethylene triamine pentacetate (DTPA; 3 calves), commonly used to measure integrity of the pulmonary epithelium, and 99mTc-labeled ovalbumin (OA; 8 calves), commonly used as a prototype allergen, were used to evaluate pulmonary clearance before, during, and after experimentally induced infection with BRSV or sham inoculation with BRSV. Uptake in plasma (6 calves) and lung-efferent lymph (1 calf) was examined.

Results—Clearance of 99mTc-DTPA was significantly increased during BRSV infection; clearance of 99mTc-OA was decreased on day 7 after inoculation. Clearance time was correlated with severity of clinical disease, and amounts of 99mTc-OA in plasma and lymph were inversely correlated with clearance time. Minimum amounts of 99mTc-OA were detected at time points when pulmonary clearance of 99mTc-OA was most delayed.

Conclusions and Clinical Relevance—BRSV caused infection of the respiratory tract with peak signs of clinical disease at 7 or 8 days after inoculation. Concurrently, there was a diminished ability to move inhaled protein antigen out of the lungs. Prolonged exposure to inhaled antigens during BRSV infection may enhance antigen presentation with consequent allergic sensitization and development of chronic inflammatory lung disease.

Impact for Human Medicine—Infection of humans with respiratory syncytial virus early after birth is associated with subsequent development of allergic asthma. Results for BRSV infection in these calves suggested a supportive mechanism for this scenario.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To describe effects of lifetime food restriction on causes of death and the association between body-mass characteristics and time of death in dogs.

Design—Paired-feeding study.

Animals—48 dogs from 7 litters.

Procedures—Dogs were paired, and 1 dog in each pair was fed 25% less food than its pair mate from 8 weeks of age until death. Numerous morphometric and physiologic measures were obtained at various intervals throughout life. Associations of feeding group to time and causes of death were evaluated, along with important associated factors such as body composition components and insulin-glucose responses.

Results—Median life span was significantly longer for the group that was fed 25% less food, whereas causes of death were generally similar between the 2 feeding groups. High body-fat mass and declining lean mass significantly predicted death 1 year prior to death, and lean body composition was associated with metabolic responses that appeared to be integrally involved in health and longevity.

Conclusions and Clinical Relevance—Results were similar to results of diet restriction studies in rodents and primates, reflecting delayed death from species- and strain-specific intrinsic causes. Clinicians should be aware that unplanned body mass changes during mid- and later life of dogs may indicate the need for thorough clinical evaluation. (J Am Vet Med Assoc 2005;226:225–231)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine effects of regional variation, interobserver variability, and vessel selection on quantitative vascular variables derived by dynamic contrast-enhanced computed tomography (DCE-CT) of the brain of clinically normal dogs.

Animals—14 adult dogs with no evidence of CNS dysfunction.

Procedures—Dogs were randomly assigned to 4 groups, and DCE-CT was performed at the level of the frontal lobe, rostral portion of the parietal-temporal lobes, caudal portions of the parietal-temporal lobes, or occipital lobe–cerebellum for groups 1 to 4, respectively. Cerebral blood flow (CBF), cerebral blood volume (CBV), and permeability in gray and white matter for both a large and small artery were calculated and compared. Values among 3 observers and 4 regions of the brain were calculated and compared.

Results—Significant interobserver variability was detected for CBF and permeability in white matter. Values calculated for large and small arteries were correlated for CBV and CBF but not for permeability. Overall mean ± SD for CBF, CBV, and permeability in gray matter was 53.5 ± 27.7 mL/min/100 g, 2.9 ± 1.4 mL/100 g, and 1.4 ± 2.2 mL/min/100 g, respectively. Mean for CBF, CBV, and permeability in white matter was 44.2 ± 28.5 mL/min/100 g, 2.5 ± 1.5 mL/100 g, and 0.9 ± 0.7 mL/min/100 g, respectively. Values did not differ significantly among brain regions.

Conclusions and Clinical Relevance—Significant regional variations were not detected for quantitative vascular variables in the brain of clinically normal dogs. However, interobserver variability and vessel selection have an important role in variable estimation.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To quantify myocardial contrast enhancement (MCE) of the left ventricle (LV) by use of cardiac magnetic resonance imaging (CMRI) in healthy cats and cats with hypertrophic cardiomyopathy (HCM) and to compare MCE between the 2 groups.

Animals—10 healthy cats and 26 Maine Coon cats with moderate to severe HCM but without clinical evidence of congestive heart failure.

Procedure—Anesthetized cats underwent gradient echo CMRI examination. Short-axis images of the LV were acquired before and 7 minutes after IV administration of gadolinium dimeglumine. Regions of interest were manually traced in the quadrants of 5 mid-LV slices acquired at end systole, and the MCE percentage was calculated from summed weight-averaged data from all slices. Doppler tissue imaging echocardiography was performed to measure the early diastolic myocardial velocity (Em) as an index of diastolic function. Three-way repeated-measures ANOVA was used to determine differences in MCE between cats with HCM and healthy cats. Simple linear regression was used to assess whether MCE was correlated with LV mass, LV mass index (LVMI), or Em. A Student t test was used to compare the SDs of the postcontrast myocardial signal intensity between the 2 groups.

Results—There was no difference in MCE between cats with HCM and healthy cats. There was no correlation of MCE with LV mass, LVMI, or Em. There was no difference in heterogeneity of signal intensities of LV myocardium between the 2 groups.

Conclusions and Clinical Relevance—Contrastenhancement CMRI was not useful in detecting diffuse myocardial fibrosis in cats with HCM. (Am J Vet Res 2005;66:1891–1894)

Full access
in American Journal of Veterinary Research