Much like in humans, heart disease is a leading cause of illness and death in cats.

About 15 percent of cats with heart disease develop arterial thromboembolism, a painful and life-threatening condition where a blood clot travels from the heart into a distal vessel and blocks blood flow to a limb. ATE, as it’s also called, carries a poor prognosis and high mortality rate for affected cats, and veterinary cardiologists are still puzzling out how to predict and prevent it.

A new study led by cardiologists and critical care specialists at the NC State College of Veterinary Medicine aims to better understand risk factors for ATE in cats with congestive heart failure, with the hope of informing the development of improved preventative therapies. 

Dr. Leo Ragazzo, a second-year cardiology resident, is leading the research along with co-principal investigators Dr. Terri DeFrancesco, a professor of cardiology and critical care and Dr. Ronald Li, an associate professor of emergency and critical care. The team’s work is supported by a nearly $50,000 grant from the EveryCat Health Foundation, a nonprofit focused on feline health research, in addition to contributions from the American College of Veterinary Internal Medicine’s Cardiology Pacemaker grant program and the NC State Feline Health Center.

“This study is truly one of the most comprehensive approaches to trying to figure out what makes these cats form blood clots,” Ragazzo says. “It’s a great partnership, tapping into everyone’s interests and expertise to develop a robust analysis.”

The research team includes experienced feline specialists, coagulation research teams and cardiologists from NC State and Cornell. Rounding out the NC State group is associate professor of emergency and critical care Dr. Alex Lynch, also the founding co-director of the Feline Health Center. Dr. Robert Goggs from Cornell University’s Comparative Coagulation Laboratory will provide advanced analytical support.

Ragazzo designed the project, which builds upon a 2022 study from an Italian veterinary clinic that compared ATE rates in cats with different symptoms of heart disease. That research found that cats with cardiogenic pleural effusion, a buildup of fluid around the lungs caused by increased cardiac pressure, showed lower rates of ATE development than cats with cardiogenic pulmonary edema, a similar condition where fluid accumulates in the lungs. 

The Italian study hypothesized that this could be because the proteins and enzymes involved in pleural effusion, or possibly the comparatively lower inflammation levels associated with the condition, could inhibit the growth of blood clots via a process called fibrinolysis.

NC State researchers will go one step further to test that hypothesis. Ragazzo’s team will sample blood from cats in heart failure with either pleural effusion or pulmonary edema, run it through tests for coagulation and fibrinolysis and determine whether there’s a difference in clot formation between the two groups.

If the team can identify risk factors for ATE through this comparative analysis, it could help direct clinicians toward targeted preventive treatments.

“Right now, how we treat these cats is relatively the same, regardless of what type of heart failure they have,” says Ragazzo, who earned his DVM from Cornell. “But if we’re able to identify one group as more susceptible, or even more specifically, locate a marker in a specific part of coagulation, fibrinolysis or an inflammatory pathway, then we can get at-risk cats on stronger anticoagulant therapy.”

This project is particularly close to Ragazzo’s heart. He entered his residency wanting to conduct ATE research, and through the guidance of DeFrancesco and the Veterinary Academic Leaders program he was able to make that goal a reality.

“In my residency interviews, they would always ask, ‘What are you interested in?’” Ragazzo says. “And I would say, ‘I love the kitties. I don’t love so much that they get ATE, but I’d love to be able to figure out what’s going on and try to prevent it from happening.’ So it’s cool to see it all come to fruition in a full-circle moment.”

The project runs through spring 2026, and researchers are currently recruiting cats in heart failure. By participating, owners will receive a free echocardiogram and personalized instruction on how to manage their cat’s heart condition at home. Interested individuals should email NCStateCardiology@ncsu.edu for details.

Ragazzo’s is not the only NC State project to receive a grant from the EveryCat Foundation. Dr. Jennifer Luff, an associate professor of anatomic pathology, received funding for a project that will investigate a potential new therapy for oral squamous cell carcinoma in cats.

Luff hopes that a treatment that targets the CDK4/6 genes that cause tumor cell growth in humans with squamous cell carcinoma will also hold promise for cats with the common and aggressive cancer. 

Are you a veterinarian or cat owner interested in learning more about advances in cat care? Register for the 2025 Feline Health Symposium, hosted by the EveryCat Health Foundation and NC State Feline Health Center in Raleigh and online from April 26-27.