In some forms of heart disease, the most severe stage progresses to congestive heart failure. At this point, the heart can no longer pump enough blood to meet the body’s needs. Fluid begins to accumulate in the lungs or abdomen, breathing can be difficult, and daily life grows harder for both dogs and the people who love them.
This month, we have focused on myxomatous mitral valve disease (MMVD), the most common type of heart disease dogs develop as they age. In advanced cases of MMVD, congestive heart failure is the most frequent clinical complication and a leading cause of cardiac-related death. Dogs with other forms of heart disease can also progress to congestive heart failure over time.
For researchers and veterinarians, congestive heart failure represents both the greatest challenge and the greatest opportunity to improve care at the moment it matters most.
Medications Help, But They Are Not Enough
Current treatment for canine congestive heart failure is aimed at controlling symptoms and improving quality of life, rather than curing the underlying disease. Management typically centers on three main types of medications:
- Diuretics, which help remove fluid build-up from the lungs or abdomen
- Pimobendan, which strengthens heart contractions and widens blood vessels, easing pressure so it is easier for the heart to pump blood to the body
- ACE inhibitors, which relax blood vessels and reduce blood pressure, lowering strain on the heart
Together, these therapies can improve comfort and extend life. However, they also come with side effects that may complicate disease management and, in some cases, contribute to further progression.
This has driven researchers to look more closely at what happens inside the body in patients with congestive heart failure.
A New Focus on Blood Chloride Levels
One area receiving renewed attention is electrolyte balance, particularly blood chloride levels.
Low blood chloride (hypochloremia) has long been observed in patients with congestive heart failure, including dogs and humans, particularly in more advanced cases and in those receiving diuretic therapy. Traditionally, this was viewed as an unavoidable side effect of diuretics, which cause the body to excrete electrolytes along with excess fluid, as well as hormonal changes that disrupt fluid and salt balance in severe heart disease, and dilution from fluid overload.
But new research suggests a more complex story.
In humans, low chloride is increasingly recognized as a marker of more severe heart failure, associated with higher risks of hospitalization and mortality. CHF-funded research led by Dr. Darcy Adin, Associate Dean of Clinical Services for Small Animals at the University of Florida, is bringing this important insight forward for dogs. Her research has shown that low blood chloride is not just a consequence of treatment in dogs, it is also an important marker of advanced heart disease.
With a second grant from the AKC Canine Health Foundation, Dr. Adin is taking the next step. What if correcting these imbalances could actually help stabilize patients and improve quality of life?
She is now studying whether supplementing with oral potassium chloride can safely restore chloride levels and, ultimately, improve outcomes and quality of life for dogs living with congestive heart failure.
As Dr. Adin puts it, the goal is both simple and profound: what can we do to make this better for the patients?
More Good Days
For Sarah Coulson, that question became deeply personal. Her dog Winston, a Clumber Spaniel mix, was seemingly healthy until subtle changes in his breathing signaled something was wrong. Within weeks, Winston was diagnosed with end-stage MMVD and congestive heart failure, and the months that followed were marked by repeated hospitalizations and difficult decisions.
After his condition stabilized, Sarah enrolled Winston in Dr. Adin’s clinical study without hesitation. What followed surprised everyone. From March through August, Winston regained joy in everyday life. He was playful, eager to eat, and even strong enough to chase squirrels in the yard again. He greeted his cardiology team with tail wags and enthusiasm each visit, seemingly as eager to see them as they were to see him. Although Winston’s disease eventually progressed and he passed away that September, participating in the study gave him five meaningful, healthy months. Months filled with vibrancy, connection, and life. Stories like Winston’s are why this research matters.
Today, Dr. Adin’s research continues to build on stories like Winston’s. Her team is actively enrolling dogs with congestive heart failure and low blood chloride levels to study whether oral potassium chloride supplementation can restore electrolyte balance and help calm the body’s stress-response signals that can worsen heart disease over time.
If successful, this work could lead to longer-term studies and real changes in how congestive heart failure is treated, shifting care toward fewer side effects, better balance, and more good days for dogs who need them most.
Hearts to Heal When It Matters Most
This research represents the heart of the Hearts to Heal initiative. It focuses on dogs at the most fragile stage of disease and asks how care can be improved today, not years from now.
By supporting studies that examine real-world treatment challenges, the AKC Canine Health Foundation helps ensure that advances in science translate into better days for dogs and clearer guidance for veterinarians and families.
To learn more about CHF or to support canine heart health research, visit akcchf.org/heartstoheal. Every contribution helps move science closer to compassion and knowledge closer to care.
Interested in Clinical Trials:
If you or someone you know would like to enroll a dog in this study, click here for more information.
