Original Project Description:
Chagas disease is a deadly parasitic heart disease of dogs, humans, and other mammals. Chagas disease is a risk where ‘kissing bug’ insect vectors are located, including South America, Central America, Mexico, and the southern United States. The risk of Chagas disease in dogs also extends to regions where dogs from the south may travel or be re-located, so dogs across the US may be at risk. However, tools to prevent and manage canine Chagas cases are lacking as there is no vaccine and no widely-validated antiparasitic treatments. The investigators have spent the past 8 years characterizing how natural infections impact the health of dogs, and how disease progresses in the absence of treatment. Given this baseline information, the team will develop and refine a canine Chagas disease scoring system to categorize the severity of the disease (measured by a panel of sensitive diagnostic tests and clinical assessments). This scoring system is a critical prerequisite for deploying new treatments.
The investigators will then treat 100 dogs with a modified dosing regimen of benznidazole. In preliminary studies, this dosing protocol achieved a high success in curing dogs of the parasitic infection while also improving their clinical status. The team will specifically enroll dogs in different stages of disease (asymptomatic dogs; dogs with mild disease; dogs with severe disease) to draw conclusions on which dogs will benefit most from treatment. Given the team’s expertise in epidemiology, cardiology, and parasitology, and their foundation of work with Chagas -infected dogs, they are uniquely qualified to carry out this study to provide tools to help dogs while also advancing the One Health initiative.
Presentations:
Kissing bugs and Chagas disease: What about the dogs? Greater Houston Golden Retriever ClubMeeting. Outreach talk. April 2025. Sarah Hamer and Rachel Busselman. Lexington, TX.
American Association of Veterinary Parasitology, St. Louis, MO, June 20-23, 2025. Invited by Elanco for sponsored evening keynote. Chagas disease- a neglected yet increasingly recognized veterinary threat. Sarah Hamer.
Greater Houston Golden Retriever Club Meeting. Kissing bugs and Chagas disease: What about the dogs? Outreach talk. April 2025. Sarah Hamer and Rachel Busselman. Lexington, TX.
Texas A&M Pre-Vet Society Meeting. September 2025. Research and Veterinary Medicine: The Case of Chagas Disease. Rachel Busselman. College Station, TX.
Fort Bend Kennel Club monthly meeting. November 2025. Kissing bugs and Chagas disease: What about the dogs? Rachel Busselman. Via zoom.
Report to Grant Sponsor from Investigator:
Canine Chagas disease is prevalent throughout the southern United States and impacts dogs in a variety of ways. While some infected dogs live without symptoms for years, others develop acute lifelimiting disease or go on to develop late-stage heart problems and heart failure due to the damage the parasite inflicts on heart tissue. Based on data we have collected from hundreds of dogs over many years, we have developed pilot Chagas disease staging criteria to help us understand disease progression and identify the best testing and treatment options for dogs at each stage of the disease.
The preliminary disease ‘stages’ of Chagas disease describe the infection status and clinical impact on the dogs, including dogs that are infected with no symptoms (stage A), infected dogs that experience some ECG abnormalities (stage B1), infected dogs that experience Echo abnormalities indicating structural changes to the heart (stage B2), and infected dogs experiencing congestive heart failure (stage C). We plan to further analyze the nearly 200 hospital-diagnosed cases since 2020 and additional research cases we have seen to make sure our staging criteria truly fits with the diagnostic and clinical realities of different types of dogs from different areas with canine Chagas disease. This staging system will ideally guide veterinarians as they diagnose, manage, and treat dogs with Chagas disease.
We have actively enrolled nearly 30 dogs in our clinical study through the Texas A&M Small Animal Hospital to evaluate an antiparasitic treatment to kill the parasite that causes Chagas disease and improve clinical outcomes. Dogs enrolled in the study have a variety of symptoms associated with Chagas disease, ranging from stage A (no symptoms) to stage C (heart failure). Owners filled out information about each dog’s health history and environmental conditions where they live. We have done a comprehensive initial clinical evaluation and detailed diagnostic tests with each dog before starting them on our treatment protocol, which will continue for 6 months. We are monitoring any clinical signs these dogs experience while on the treatment protocol by asking the owners to fill out a survey every two weeks and get in touch with us in the meantime if something changes. Currently, 23 dogs are between 4 and 18 weeks into their treatment protocols. We are in the process of further analyzing the data collected about potential environmental risks of Chagas disease and historic clinical signs, as well as the physical exam, ECGs, echocardiogram, and parasite testing findings for each dog.
We will continue actively monitoring this group of dogs and look forward to their 6-month recheck appointments after they have finished the benznidazole treatment. We will also enroll more dogs from a kennel environment to increase the number of dogs we can treat and monitor as part of this study.