Cardiology

Did you know that approximately 10% of dogs presented to first opinion practices have heart disease, with the majority of cases suffering with myxomatous mitral valve disease (MMVD) or, less commonly, dilated cardiomyopathy (DCM)?

Both diseases may eventually lead to overt congestive heart failure, a condition for which treatment requires not only initiation of appropriate medications, but also long-term monitoring and ongoing tailored dose adjustments, in order to gain the best outcome for the patient.

What are the clinical signs of canine congestive heart failure?

 The signs of congestive heart failure occur as a result of forwards failure (reduced cardiac output) or backwards failure (ascites / pulmonary oedema).

Clinically, the dog may display breathlessness, exercise intolerance and sometimes weight loss and coughing. However, these signs may also indicate a respiratory problem, which can make diagnosis challenging.

How do you diagnose canine congestive heart failure?

 Unfortunately, there is no one single diagnostic test for congestive heart failure. Diagnosis is usually made using a combination of history, physical examination, bloodwork and further imaging. Findings may include:

Physical Examination:

Increased respiratory rate and effort
Presence of a significant heart murmur
Increased heart rate
Loss of sinus arrhythmia

Bloodwork:

Elevated cardiac biomarkers

Radiography:

Increased overall heart size
Bulging left atrium
Pulmonary venous congestion

Echocardiology:

Increased left atrial : aortic ratio

 

What are the treatment options for canine congestive heart failure?

Once a dog has been diagnosed with congestive heart failure, the next step is to develop a treatment plan best suited to the individual patient.

A combination of multiple medications are usually prescribed to dogs in congestive heart failure. Pimobendan is a key component in this treatment matrix. It is beneficial in CHF cases due to its dual action:

Positive inotropy for improved contractility without increasing myocardial oxygen demand
Vasodilation for reduced preload and afterload, easing the workload of the failing heart

Ultimately, the primary objective with treatment is to improve the dogs’ quality-of-life.

Regular treatment and monitoring will then, in turn, improve the dogs’ breathing. Their exercise tolerance will improve, any ascites will be resolved and there will be a reduction in the severity of the dogs’ cough.

How do I monitor a dog with heart failure?

Regular check-up appointments are vital for any dog with a chronic medical condition. Those with CHF will require routine physical examinations, including a thorough auscultation of the thorax, blood pressure assessment and routine bloodwork (primarily to monitor for pre-renal azotaemia as a result of diuresis).

Alongside regular in-clinic monitoring, it is important to work with the owner to explain how they can help monitor their dogs condition at home. Improvements in resting respiratory rate and effort are often very noticeable to owners, and providing them with easy ways in which to record this improvement can also help with the overall veterinary assessment.

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