Browsing by Author "Saunders, Ashley"

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    Cardiac magnetic resonance imaging detects myocardial abnormalities in naturally infected dogs with chronic, asymptomatic Chagas disease
    (2023-04-14) Matthews, Derek; Fries, Ryan; Jeffery, Nicholas; Hamer, Sarah; Saunders, Ashley
    Trypanosoma cruzi infection causes inflammation and fibrosis, resulting in cardiac damage in dogs. The objectives of this study were to describe cardiac magnetic resonance imaging (CMR) in naturally infected dogs with chronic Chagas disease and the frequency of abnormalities for CMR and cardiac diagnostic tests. Ten asymptomatic, client-owned dogs seropositive for T. cruzi were prospectively enrolled in an observational study evaluating echocardiography, ECG (standard and ambulatory), cardiac troponin I (cTnI), and CMR. Standard ECG measurements (3/10) and cTnI concentration (1/10) outside the reference range were uncommon. Ambulatory ECG abnormalities were documented more frequently (6/10 dogs) than with standard ECG and included ventricular arrhythmias (4), supraventricular premature beats (3), second-degree atrioventricular block (2), and sinus arrest (1). Echocardiographic abnormalities were documented in 6/10 dogs including mildly increased left ventricular internal dimension in diastole (1) and decreased right ventricular (RV) systolic function based on reductions in tricuspid annular plane systolic excursion (3) and RV S’ (4). Abnormalities were detected with CMR in 7/10 dogs including delayed myocardial en-hancement in 5 of which 2 also had increased extracellular volume, abnormal wall motion in 5, and loss of apical compact myocardium in 1. In conclusion, CMR abnormalities were common, and the results of this study suggest CMR can provide useful information in dogs with T. cruzi in-fection and may support naturally infected dogs for future clinical investigation as an animal model for Chagas disease.
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    Collection of triatomines from sylvatic habitats by a Chagas-positive, trained scent-detection canine in Texas, USA
    (2022-09-13) Christopher, Devin; Curtis-Robles, Rachel; Hamer, Gabriel; Bejcek, Justin; Saunders, Ashley; Rochell, Walter; Cropper, Thomas Leo; Hamer, Sarah
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    DOG-VECTOR-PARASITE INTERACTIONS IN THE CHAGAS DISEASE SYSTEM: CARDIAC CLINIC STATUS OF NATURALLY-INFECTED DOGS ACROSS THE US
    (2019-07-09) Meyers, Alyssa Catherine; Hamer, Sarah; Hamer, Gabe; Cummings, Kevin; Saunders, Ashley
    In the southern U.S., triatomine vectors maintain Trypanosoma cruzi- the protozoan parasite that causes Chagas disease in humans and animals- in sylvatic cycles. Infection with T. cruzi may be asymptomatic or lead to heart disease and death. Using dogs as a model host system, our objectives were to improve the ecological and clinical understanding of Chagas disease in the U.S. We collected 461 triatomines from Big Bend National Park from 2015- 2017 and found an overall infection prevalence of 23.1%. Blood meal analysis on 42 triatomines showed DNA evidence of humans, domestic animals, wild birds and mammalian wildlife. In 2015-17, we sampled 1,660 working dogs from 43 states using three independent serology assays to detect a seroprevalence of 7.3% (CI: 6.1-8.6%). To better characterize the cardiac outcomes in T. cruzi-infected dogs we applied a 24-hour Holter monitor to 17 T. cruzi-infected, 18 uninfected dogs and 4 dogs with discordant serology results. The presence of ECG abnormalities varied by T. cruzi infection status (p<0.001) and positive dogs had higher serum concentrations of cardiac troponin I (cTnI), a biomarker for cardiac injury, than both negative dogs (p=0.044) and discordant dogs (p=0.06). Finally, we performed a retrospective study looking at 375 dogs presented to a teaching hospital in Texas. T. cruzi-infected dogs (N=63, 16.8%) were significantly younger than negative dogs (N=312) (mean 5.9 vs. 7.4 yr old respectively; p=0.0069) with no difference in infections by sex or breed. Infected dogs were more likely to have ventricular arrhythmias (28.6%), combinations of ECG abnormalities, and cTnI greater than 0.129 ng/mL (ADVIA assay). Combining ecological and clinical approaches to enhance our understanding of Chagas disease should provide insight for vector control and measures to protect veterinary and public health.
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    High incidence of Trypanosoma cruzi infections in a cohort of dogs directly detected through longitudinal tracking at multi-dog kennels, Texas, USA
    (2021-06-21) Busselman, Rachel; Meyers, Alyssa; Zecca, Italo; Auckland, Lisa; Castro, Andres; Dowd, Rebecca; Curtis-Robles, Rachel; Hodo, Carolyn; Saunders, Ashley; Hamer, Sarah
    Canine Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is increasingly recognized as a health concern for dogs in the USA, and infected dogs may signal geographic regions of risk for human disease. Dogs living in multi-dog kennel environments where triatomine vectors are endemic may be at high risk for infection. We monitored a cohort of 64 T. cruzi-infected and uninfected dogs from across 10 kennels in Texas, USA, to characterize changes in infection status over time. We used robust diagnostic criteria in which reactivity on multiple independent platforms was required to be considered positive. Among the 30 dogs enrolled as serologically- and/or PCR-positive, all but one dog showed sustained positive T. cruzi diagnostic results over time. Among the 34 dogs enrolled as serologically- and PCR-negative, 10 new T. cruzi infections were recorded over a 12-month period. The resulting incidence rate was 30.7 T. cruzi infections per 100 dogs per year. This study highlights the risk of T. cruzi infection to dogs in kennel environments, despite multiple vector control methods employed by kennel owners. To protect both dog and human health, there is an urgent need to develop more integrated vector control methods as well as prophylactic and curative antiparasitic treatment options for T. cruzi infection in dogs.
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    Peer Review of Teaching Classroom Observation Feedback Form
    (2018-06-20) Macik, Maria; Chaney, Kristin; Saunders, Ashley; Cornell, Karen
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    Peer Review of Teaching Observation Notes
    (2018-06-22) Macik, Maria; Chaney, Kristin; Saunders, Ashley
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    Peer Review of Teaching Post-Observation Reflection Form
    (2018-06-22) Macik, Maria; Chaney, Kristin; Saunders, Ashley; Cornell, Karen
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    Peer Review of Teaching Pre-Observation Form
    (2018-06-22) Macik, Maria; Chaney, Kristin; Saunders, Ashley; Cornell, Karen