Congestive Heart Failure in Dogs: Signs, Diagnosis, Monitoring, and Care

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Congestive heart failure (CHF) in dogs is a clinical syndrome in which the heart can no longer pump blood effectively, leading to fluid accumulation in the lungs (pulmonary edema), the chest cavity (pleural effusion), or the abdomen (ascites). For owners, the earliest signs of dog heart failure symptoms often include a persistent cough, labored breathing, reduced exercise tolerance, and restlessness, especially at night. Immediate veterinary evaluation is critical because CHF is a progressive condition that, without treatment, carries a poor prognosis. However, with modern veterinary therapies, many dogs enjoy months to years of good quality life after diagnosis.

This article provides a definitive, evidence-based review of canine congestive heart failure, covering its pathophysiology, causes, clinical signs, diagnostic methods, monitoring strategies, and current treatment protocols. The content is grounded in peer-reviewed veterinary research and international clinical guidelines.

At a Glance: Key Facts About CHF in Dogs

Anatomy and Pathophysiology of Canine Heart Failure

The heart is a dual-pump organ. The right side receives deoxygenated blood from the body and pumps it through the lungs. The left side receives oxygenated blood from the lungs and pumps it to the rest of the body. In CHF, the failing heart cannot maintain adequate cardiac output. The body compensates through neurohormonal activation, including the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system. These compensatory mechanisms initially help maintain blood pressure but eventually become maladaptive, causing vasoconstriction, sodium and water retention, and further cardiac remodeling.

In left-sided CHF, the most common form in dogs, increased pressure in the left atrium and pulmonary veins forces fluid into the lung interstitium and alveoli, producing pulmonary edema. In right-sided CHF, fluid accumulates in the systemic venous system, leading to ascites, pleural effusion, and peripheral edema. Many dogs with advanced disease develop biventricular failure.

Recent research has clarified the molecular mechanisms underlying CHF. The type-1 ryanodine receptor (RyR1), traditionally associated with skeletal muscle, is also expressed in cardiac myocytes. In dogs and humans with cardiac hypertrophy and heart failure, RyR1 expression increases, and this receptor contributes to abnormal calcium release from the sarcoplasmic reticulum via the type-2 ryanodine receptor (RyR2) [10]. This calcium dysregulation impairs both contraction and relaxation of the heart muscle.

Primary Causes of Congestive Heart Failure in Dogs

The two most common acquired heart diseases leading to CHF in dogs are myxomatous mitral valve disease (MMVD) and dilated cardiomyopathy (DCM).

Myxomatous Mitral Valve Disease (MMVD) accounts for approximately 75% of all canine heart disease. It is characterized by progressive thickening and prolapse of the mitral valve leaflets, leading to mitral regurgitation. The regurgitant jet causes volume overload of the left atrium and left ventricle, eventually resulting in left-sided CHF. MMVD is most prevalent in small-breed dogs such as Cavalier King Charles Spaniels, Dachshunds, Miniature Poodles, Maltese, and Toy Poodles [1]. The condition is age-related and nearly universal in senior small-breed dogs.

Dilated Cardiomyopathy (DCM) is a primary myocardial disease in which the heart muscle becomes thin and weak, resulting in a dilated, poorly contractile left ventricle. DCM is most common in large and giant breeds, including Doberman Pinschers, Great Danes, Boxers, and Irish Wolfhounds. It can be genetic or acquired (e.g., taurine deficiency in certain breeds). Thoracic radiography in DCM reveals generalized cardiomegaly with pulmonary venous distension, and the vertebral left atrial size (VLAS) and radiographic left atrial dimension (RLAD) are useful measurements for assessing left atrial enlargement [16].

Other causes of CHF include:

• Chronic valvular fibrosis (advanced MMVD)
• Infectious endocarditis (bacterial infection of heart valves)
• Myocarditis (e.g., canine parvovirus in neonates) [18]
• Pericardial effusion (fluid in the sac around the heart)
• Heartworm disease (Dirofilaria immitis)
• Congenital heart defects (e.g., patent ductus arteriosus, subaortic stenosis)
• Arrhythmogenic right ventricular cardiomyopathy (e.g., in Boxers)

Risk Factors and Breed Predispositions

Risk factors for CHF in dogs include:

• Age: MMVD prevalence increases with age; most dogs are over 8 years at diagnosis [1].
• Breed size: Small breeds (< 15 kg) are predisposed to MMVD; large breeds to DCM.
• Sex: Male dogs may be slightly overrepresented for MMVD.
• Genetics: Specific genetic mutations have been identified for DCM in Dobermans and Boxers.
• Nutrition: Taurine deficiency can cause reversible DCM in certain breeds (e.g., Golden Retrievers, Newfoundlands, Cocker Spaniels).
• Obesity: Increases hemodynamic load on the heart.
• Concurrent disease: Chronic kidney disease, hypertension, and hyperthyroidism (rare in dogs) can exacerbate heart disease.

Recognizing Dog Heart Failure Symptoms

The clinical signs of CHF depend on the severity and laterality of failure. Owners and veterinarians should recognize these common presentations.

Left-sided CHF (most common in MMVD and DCM):

• Cough (often moist, productive, worse at night or after lying down)
• Tachypnea (rapid breathing at rest)
• Dyspnea (labored breathing)
• Orthopnea (difficulty breathing when lying flat; dog may prefer to sit or stand)
• Exercise intolerance
• Cyanosis (blue or purple mucous membranes)
• Collapse or syncope (fainting)
• Crackles (rales) on thoracic auscultation
• Muffled heart sounds if pleural effusion is present

Right-sided CHF:

• Abdominal distension (ascites)
• Jugular venous distension
• Hepatomegaly (enlarged liver)
• Peripheral edema (pitting edema of limbs, rarely seen in dogs)
• Weight loss (cardiac cachexia)
• Weakness

Subtle signs in early or compensated CHF:

• Restlessness, especially at night
• Increased sleeping respiratory rate (SRR) > 30 breaths per minute
• Decreased appetite
• Lethargy
• Behavioral changes (e.g., seeking more attention or hiding)

The classic "dog heart failure symptoms" that owners report first are a persistent cough that is not productive of phlegm, and rapid breathing that does not resolve with rest. In one study of dogs with MMVD stage C, 77.5% presented with left-sided CHF at the time of diagnosis [19].

Veterinary Examination and Diagnostic Approach

A thorough diagnostic workup is essential to confirm CHF, determine its cause, assess severity, and guide therapy.

Physical Examination

The veterinarian will perform a complete physical exam, focusing on:

• Thoracic auscultation: Heart murmur (typically left apical systolic for MMVD, left basilar systolic for DCM), gallop rhythm, arrhythmias, lung crackles, or muffled sounds.
• Mucous membrane color and capillary refill time: Pale, cyanotic, or prolonged CRT indicate poor perfusion.
• Jugular vein assessment: Distension or pulsation suggests right-sided CHF.
• Abdominal palpation: Hepatomegaly, splenomegaly, or fluid wave (ascites).
• Femoral pulse quality: Weak or irregular pulses suggest low cardiac output or arrhythmia.

Thoracic Radiography (Chest X-rays)

Radiography is the cornerstone for diagnosing pulmonary edema and pleural effusion. In left-sided CHF, radiographic findings include:

• Interstitial to alveolar pulmonary infiltrates (typically in the perihilar region in MMVD, diffuse in DCM)
• Enlarged left atrium (seen as a bulge on the dorsoventral view)
• Enlarged pulmonary veins (pulmonary venous distension)
• Generalized cardiomegaly

The right pulmonary vein-to-pulmonary artery ratio (RPV/RPA) has been investigated as a diagnostic tool. While the RPV/RPA measured at the end of the T wave has high sensitivity (96.6%) for detecting stage C CHF, its specificity is low (36.8%), meaning many dogs without CHF will have an abnormal ratio. A more accurate measurement is the right pulmonary vein-to-aortic root ratio (RPV/Ao) at the end of the T wave, with a cutoff > 1.07 providing 83.1% sensitivity and 71.1% specificity for identifying CHF [6].

In DCM, radiography shows generalized cardiomegaly with a globoid heart shape, pulmonary venous distension, and often pleural effusion. The combination of VLAS and RLAD measurements improves diagnostic accuracy [16].

Echocardiography (Cardiac Ultrasound)

Echocardiography is the definitive imaging modality for diagnosing the underlying heart disease. It provides:

• Two-dimensional imaging: Valve morphology, chamber dimensions, wall thickness, and pericardial effusion.
• M-mode: Left ventricular systolic and diastolic dimensions, fractional shortening, and ejection fraction.
• Doppler: Velocity and direction of blood flow, severity of regurgitation, and estimation of pulmonary artery pressure.

In MMVD, echocardiography reveals thickened, prolapsing mitral valve leaflets, left atrial enlargement, and a regurgitant jet across the mitral valve. In DCM, the left ventricle is dilated with reduced fractional shortening (< 20-25%) and ejection fraction.

Advanced deep learning models, such as GGNet, can fuse echocardiographic and radiographic data to accurately stage MMVD. One study using GGNet on 902 dogs achieved high accuracy in classifying normal, stage B1, stage B2, and stage C disease [13]. While these tools are not yet widely available, they represent the future of automated cardiac diagnosis.

Electrocardiography (ECG)

An ECG is indicated to detect arrhythmias (atrial fibrillation, ventricular premature complexes, ventricular tachycardia) and conduction disturbances. Atrial fibrillation is common in advanced DCM and severe MMVD.

Blood Work

Laboratory tests are essential for baseline assessment and monitoring:

• Complete blood count: May show stress leukogram or anemia.
• Serum biochemistry: Evaluate renal function (creatinine, BUN), electrolytes (sodium, potassium, chloride), and liver enzymes.
• Cardiac biomarkers: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is elevated in CHF and helps differentiate cardiac from respiratory causes of dyspnea.
• Thyroid profile: Hyperthyroidism can cause secondary cardiomyopathy.

Serum chloride concentration has emerged as a key prognostic marker. In dogs with CHF, lower serum chloride is independently associated with higher concentrations of angiotensin peptides and aldosterone. Each 5 mmol/L decrease in chloride corresponds to a 32-45% increase in angiotensin metabolites and a 39% increase in aldosterone [3]. Hypochloremia (chloride < 100 mEq/L) identifies a distinct RAAS phenotype with higher neurohormonal activation.

Urinalysis and Urine Electrolytes

Urinalysis is important to assess renal function and detect proteinuria. In acute CHF, spot urinary electrolyte measurements after intravenous furosemide provide valuable prognostic information. Higher urinary sodium concentration and urinary sodium-to-potassium ratio (uNa:K) are associated with greater improvement in radiographic pulmonary congestion and shorter hospitalization. Dogs that survive to discharge have a higher uNa:K than those that die during hospitalization [2].

In chronic CHF, urine sodium concentration (uNa) can assess diuretic responsiveness. In one study, 45% of dogs receiving oral loop diuretics had consistently low uNa (< 70 mmol/L), indicating poor diuretic responsiveness [4]. These dogs may require higher doses or alternative diuretic strategies.

Advanced Diagnostics

• Arterial blood gas: Assess oxygenation and acid-base status.
• Blood pressure measurement: Hypertension can exacerbate CHF.
• Heartworm antigen testing: Indicated in endemic areas.
• Cardiac catheterization: Rarely needed for CHF diagnosis but may be used for congenital defects.
• Gut microbiota analysis: Emerging research suggests that gut dysbiosis may play a role in CHF. Dogs with CHF have overabundance of Escherichia/Shigella and reduced Megamonas compared to healthy controls [15]. The clinical utility of microbiome testing is still under investigation.

Staging and Classification

The American College of Veterinary Internal Medicine (ACVIM) staging system for MMVD is widely used:

• Stage A: High risk but no structural heart disease (e.g., Cavalier King Charles Spaniel puppy).
• Stage B1: Structural heart disease (murmur) without cardiomegaly or clinical signs.
• Stage B2: Structural heart disease with cardiomegaly (radiographic or echocardiographic) but no clinical signs.
• Stage C: Current or past clinical signs of CHF.
• Stage D: End-stage disease refractory to standard therapy.

Stage D is defined by the need for high-dose diuretics (furosemide > 8 mg/kg/day or equivalent torasemide dose) [19]. Dogs in stage D have a median survival time of 155 days after diagnosis, with 77.5% having left-sided CHF at presentation [19].

Evidence-Based Management of Congestive Heart Failure

The goals of CHF therapy are to relieve congestion, improve cardiac output, slow disease progression, and maintain quality of life. Treatment is tailored to the underlying cause, stage, and individual patient response.

Acute Decompensated CHF (Emergency Management)

Dogs presenting with acute respiratory distress from pulmonary edema require immediate intervention:

1. Oxygen therapy: Flow-by, mask, or oxygen cage.
2. Diuresis: Intravenous furosemide (2 mg/kg bolus, repeated as needed). The first spontaneous urination within 2 hours after furosemide provides urine for electrolyte analysis [2].
3. Vasodilation: Nitroglycerin paste (topical) or sodium nitroprusside (IV) for afterload reduction.
4. Positive inotropy: Pimobendan (0.2-0.3 mg/kg PO or IV) or dobutamine (IV) for DCM.
5. Thoracocentesis: If pleural effusion is present.
6. Sedation: Butorphanol or acepromazine to reduce anxiety and oxygen demand.

The circulatory equilibrium framework helps understand the hemodynamic effects of inotropes. In a canine model of acute heart failure, milrinone (a phosphodiesterase III inhibitor) reduced effective stressed blood volume and increased cardiac output but caused a decrease in aortic pressure [17]. This highlights the delicate balance between improving pump function and maintaining perfusion pressure.

Chronic CHF Management

Loop Diuretics Furosemide is the first-line diuretic for CHF. The goal is to use the lowest effective dose to maintain euvolemia. Torasemide is a more potent alternative with better bioavailability and longer duration of action. In stage D dogs, torasemide and furosemide show similar survival times, though torasemide may cause higher creatinine and lower potassium levels [19].

A subset of dogs with MMVD-related CHF may achieve stability allowing diuretic withdrawal. In a retrospective study of 3,055 dogs, 6 dogs (0.2%) achieved stability without diuretics for at least 1 year. These dogs had azotemia, radiographic evidence of reduced heart size, and long-term clinical stability [1]. This phenomenon is rare but suggests that reversible factors may contribute to CHF in some cases.

Pimobendan Pimobendan is a positive inotrope and vasodilator (inodilator) that improves cardiac output and survival in dogs with CHF. It is the standard of care for MMVD stage C and D. The recommended dose is 0.2-0.3 mg/kg PO every 12 hours. Three-dimensional (3D) printed pimobendan tablets (printlets) are being developed to allow dose flexibility and smaller tablet sizes, which may improve compliance in small dogs [20].

The timing of pimobendan initiation is critical. Dogs that receive pimobendan in the preclinical stage (stage B2) and then progress to CHF have shorter survival from the onset of CHF compared to pimobendan-naive dogs (168 days vs. 359 days) [5]. This does not mean pimobendan is harmful; rather, it suggests that dogs requiring preclinical therapy have more aggressive disease. The overall benefit of preclinical pimobendan in delaying CHF onset is well established.

Angiotensin-Converting Enzyme Inhibitors (ACEi) Enalapril or benazepril (0.25-0.5 mg/kg PO every 12-24 hours) inhibit RAAS activation, reducing vasoconstriction and sodium retention. ACEi therapy is associated with longer survival to cardiac mortality in dogs with CHF [7].

Sacubitril/Valsartan This angiotensin receptor-neprilysin inhibitor (ARNI) is a newer option for CHF in dogs. In a retrospective study of 50 dogs with MMVD and CHF, sacubitril/valsartan (mean dose 18.1 mg/kg PO every 12 hours) was well tolerated, with only 6% adverse events. Median survival was 577 days for all dogs, and 1,149 days for stage C dogs [8]. Owners reported improved energy and exercise capacity in 83% of dogs. This drug represents a promising addition to the CHF armamentarium.

Spironolactone This aldosterone antagonist (1-2 mg/kg PO every 12-24 hours) provides additional RAAS blockade and has diuretic-sparing effects. It is often added in stage C and D.

Beta-Blockers Carvedilol or atenolol may be used in dogs with DCM or arrhythmias, but they must be introduced cautiously at low doses due to negative inotropic effects.

Novel Therapies Under Investigation

• Ulacamten: A cardiac myosin inhibitor designed for heart failure with preserved ejection fraction (HFpEF). Preclinical studies show low-to-moderate clearance and moderate bioavailability in dogs [12].
• Aficamten: Another myosin inhibitor that increases diastolic chamber volumes without reducing cardiac output in healthy dogs, due to preserved length-dependent force generation [14].
• MRS2339: A nucleotide activator of cardiac P2X4 receptors that improves systolic function in canine models of heart failure by increasing cyclic GMP levels [9].

These agents are not yet approved for clinical use in dogs but represent active areas of research.

Monitoring Heart Failure in Dogs

Regular monitoring is essential to adjust therapy and detect decompensation early.

Home Monitoring by Owners

• Resting respiratory rate: Count breaths per minute when the dog is asleep or resting quietly. A rate consistently > 30 breaths per minute warrants veterinary attention. A rate > 40 breaths per minute is an emergency.
• Body weight: Daily or weekly weighing can detect fluid retention (weight gain > 2-3%).
• Appetite and activity: Decreased appetite or lethargy may signal worsening CHF.
• Cough frequency: Note any increase in coughing, especially at night.
• Gum color: Pale or blue gums indicate poor oxygenation.

Veterinary Monitoring

• Serial thoracic radiographs: Assess pulmonary edema severity and cardiac size.
• Echocardiography: Every 3-12 months to track disease progression.
• Blood work: Renal function, electrolytes, and NT-proBNP every 1-3 months.
• Urine electrolytes: Spot uNa can assess diuretic responsiveness in chronic CHF [4].
• Blood pressure: Monitor for hypotension or hypertension.
• ECG: If arrhythmias are present or suspected.

Urine Sodium as a Monitoring Tool In dogs receiving oral loop diuretics for chronic CHF, urine sodium concentration (uNa) is a practical measure of diuretic responsiveness. A uNa < 70 mmol/L suggests poor response and may indicate the need for dose adjustment or combination therapy. Importantly, the dose of diuretic and time from last administration do not reliably predict uNa, highlighting the value of direct measurement [4].

Serum Chloride and RAAS Monitoring Hypochloremia is a marker of RAAS activation and poor prognosis. Monitoring serum chloride helps identify dogs that may benefit from more aggressive RAAS blockade or chloride supplementation [3].

Prognosis and Survival

Survival times for dogs with CHF vary widely based on etiology, stage, and response to therapy.

Factors associated with longer survival include:

• ACE inhibitor therapy [7]
• Higher uNa:K ratio at presentation [2]
• Normal serum chloride concentration [3]
• Good diuretic responsiveness [4]
• Stage C (vs. D) at diagnosis [8, 19]

Factors associated with shorter survival include:

• Preclinical pimobendan use (reflects more aggressive disease) [5]
• Hypochloremia [3]
• Low uNa on chronic diuretic therapy [4]
• Development of azotemia (cardiorenal syndrome) [11]
• Pulmonary hypertension [19]
• Arrhythmias [19]

Complications and Comorbidities

Cardiorenal Syndrome Heart and kidney function are intimately linked. In dogs with MMVD, cardiorenal syndrome (CRS) is characterized by progressive renal dysfunction secondary to reduced cardiac output and neurohormonal activation. Serum peptidomic profiling has identified signatures associated with peroxisomal and mitochondrial pathways in dogs with MMVD-associated CRS [11]. These findings may lead to earlier detection of kidney involvement.

Pulmonary Hypertension Elevated pulmonary artery pressure is common in advanced MMVD and DCM, occurring in 37.7% of stage D dogs [19]. It worsens dyspnea and right-sided CHF. Treatment includes sildenafil or tadalafil.

Arrhythmias Atrial fibrillation, ventricular premature complexes, and ventricular tachycardia are common in advanced CHF. They can cause syncope or sudden death. Management includes antiarrhythmic drugs (e.g., amiodarone, sotalol, mexiletine) and, in some cases, pacemaker implantation.

Cachexia Cardiac cachexia (muscle wasting) is a poor prognostic sign. Nutritional support with high-quality protein and omega-3 fatty acids may help.

Prevention and Early Intervention

Preventing CHF involves identifying and managing heart disease before clinical signs develop.

• Regular veterinary checkups: Annual auscultation for heart murmurs in at-risk breeds.
• Echocardiographic screening: For breeds predisposed to MMVD or DCM.
• Preclinical pimobendan: In dogs with MMVD stage B2 (cardiomegaly without CHF), pimobendan reduces the risk of CHF onset and prolongs survival.
• Weight management: Obesity increases cardiac workload.
• Dental health: Periodontal disease is associated with endocarditis.
• Heartworm prevention: Year-round prevention in endemic areas.
• Taurine supplementation: For breeds at risk of taurine-deficient DCM.

Unsafe Home Remedies and Misconceptions

Owners should avoid these common but dangerous practices:

• Human heart medications: Never give dogs human furosemide, ACE inhibitors, or beta-blockers without veterinary guidance. Doses are different and some human formulations contain toxic excipients (e.g., xylitol).
• Herbal diuretics: Dandelion, parsley, and juniper berry are not effective for CHF and can cause electrolyte imbalances.
• Salt restriction: While low-sodium diets are recommended, severe salt restriction can cause hyponatremia and worsen RAAS activation. Use veterinary therapeutic diets formulated for heart disease.
• Withholding water: Dogs with CHF need access to fresh water. Water restriction can cause dehydration and worsen kidney function.
• Cough suppressants: Over-the-counter cough medicines (e.g., dextromethorphan) do not treat the underlying cause and can mask worsening CHF.
• Essential oils: Some oils (e.g., tea tree, wintergreen) are toxic to dogs and can cause respiratory distress.

Emergency Red Flags

Owners should seek immediate veterinary care if their dog shows any of the following:

• Respiratory rate > 40 breaths per minute at rest
• Open-mouth breathing or panting when at rest
• Blue or pale gums
• Collapse or fainting
• Coughing up frothy pink fluid
• Inability to lie down or rest comfortably
• Distended abdomen with respiratory distress
• Sudden weakness or paralysis of hind limbs (suggestive of aortic thromboembolism)

Clinical Reasoning and Diagnostic Workflow: From Suspicion to Confirmation

The diagnostic journey for congestive heart failure in dogs begins not in the veterinary clinic, but in the owner's home. Recognizing the earliest dog heart failure symptoms and understanding when to seek veterinary attention can significantly alter the disease trajectory. When an owner reports a cough that persists beyond a few days, especially one that seems worse when the dog is lying down or during the night, the clinical reasoning process should immediately consider left-sided CHF as a differential diagnosis. However, cough in dogs is notoriously nonspecific, and conditions such as tracheal collapse, chronic bronchitis, pneumonia, and even laryngeal paralysis can mimic the cough of CHF. This diagnostic ambiguity underscores why thoracic radiography remains the cornerstone of initial evaluation.

The clinical reasoning framework for CHF diagnosis follows a stepwise approach. First, the veterinarian must determine whether respiratory signs are cardiac or noncardiac in origin. A dog presenting with tachypnea and cough may have pulmonary edema, but could also have primary respiratory disease, neoplasia, or a noncardiogenic cause of pulmonary infiltrates. The presence of a heart murmur on auscultation increases the likelihood of cardiac disease, but not all dogs with murmurs have CHF, and not all dogs with CHF have audible murmurs. In advanced DCM, for instance, murmurs may be soft or absent due to poor cardiac output. The combination of a left apical systolic murmur, a gallop rhythm, and pulmonary crackles on auscultation provides strong clinical evidence for left-sided CHF, but definitive confirmation requires imaging.

Once CHF is suspected, the diagnostic workflow proceeds to thoracic radiography. The classic radiographic pattern of left-sided CHF in MMVD is a perihilar interstitial to alveolar pulmonary infiltrate, often described as a butterfly or bat-wing pattern. However, this classic appearance is not always present. In dogs with DCM, the pulmonary edema pattern is often more diffuse and may be indistinguishable from other causes of diffuse lung disease. The radiographic finding of pulmonary venous distension, particularly when the pulmonary veins are larger than the corresponding pulmonary arteries, adds specificity to the diagnosis. The right pulmonary vein-to-pulmonary artery ratio (RPV/RPA) has been studied as a quantitative tool, but its low specificity (36.8%) means that many dogs without CHF will have an abnormal ratio, limiting its clinical utility as a standalone test [6]. The more accurate right pulmonary vein-to-aortic root ratio (RPV/Ao), with a cutoff greater than 1.07, provides better balance between sensitivity (83.1%) and specificity (71.1%) [6]. These measurements require careful timing to the end of the T wave on ECG-gated radiographs, which is not always feasible in clinical practice.

Echocardiography is the definitive diagnostic step after radiography confirms pulmonary edema or pleural effusion. The echocardiogram serves two purposes: confirming the underlying heart disease and assessing its severity. In MMVD, the echocardiographer evaluates mitral valve morphology, measures left atrial and ventricular dimensions, and quantifies the severity of mitral regurgitation using color flow Doppler. The left atrial-to-aortic root ratio (LA:Ao) is a key measurement for staging. In DCM, the echocardiogram reveals a dilated, poorly contractile left ventricle with reduced fractional shortening and ejection fraction. The echocardiogram also helps identify less common causes of CHF, such as pericardial effusion, heartworm disease, or congenital defects.

Advanced diagnostic tools are emerging but not yet widely available. Deep learning models like GGNet can fuse echocardiographic and radiographic data to accurately stage MMVD, achieving high accuracy in classifying normal, stage B1, stage B2, and stage C disease [13]. While these tools represent the future of automated cardiac diagnosis, they are currently limited to research settings and specialized referral centers. For most general practitioners, the combination of physical examination, thoracic radiography, and echocardiography remains the gold standard for diagnosing canine congestive heart failure.

Evidence Limitations and Knowledge Gaps in Canine CHF Research

While the veterinary literature on congestive heart failure in dogs has expanded considerably, clinicians must recognize the limitations of the available evidence. Many studies are retrospective, single-center, and involve relatively small sample sizes. Prospective, randomized, controlled trials are less common due to the ethical challenges of withholding treatment from dogs with CHF and the financial constraints of conducting large-scale veterinary clinical trials. These limitations affect the strength of recommendations for many aspects of CHF management.

One notable evidence gap concerns the optimal timing and dosing of loop diuretics. Furosemide is the most commonly used diuretic, but its dosing is largely empirical. The goal of using the lowest effective dose to maintain euvolemia is sound in principle, but what constitutes the lowest effective dose varies widely among individual dogs. The concept of diuretic responsiveness, as measured by urine sodium concentration (uNa), is gaining traction, but the evidence base is still developing. In one study, 45% of dogs receiving oral loop diuretics for chronic CHF had consistently low uNa (< 70 mmol/L), indicating poor diuretic responsiveness [4]. However, the clinical implications of this finding are not fully understood. Does low uNa simply reflect adequate diuresis and euvolemia, or does it indicate diuretic resistance that requires dose escalation or combination therapy? The answer likely depends on the clinical context, and more research is needed to establish uNa targets and treatment algorithms.

Another evidence limitation concerns the use of pimobendan in preclinical disease. The EPIC trial established that pimobendan delays the onset of CHF in dogs with MMVD stage B2. However, a subsequent study found that dogs receiving preclinical pimobendan who later developed CHF had shorter survival from the onset of CHF compared to pimobendan-naive dogs (168 days vs. 359 days) [5]. This finding does not indicate that pimobendan is harmful; rather, it suggests that dogs requiring preclinical therapy have more aggressive disease that progresses faster once CHF develops. The overall benefit of preclinical pimobendan in delaying CHF onset is well established, but the survival data from CHF onset highlight the heterogeneity of disease progression and the need for individualized prognostic counseling.

The evidence for newer therapies such as sacubitril/valsartan is promising but limited. The retrospective study reporting median survival of 1,149 days for stage C dogs treated with sacubitril/valsartan is encouraging, but the study included only 50 dogs and lacked a control group [8]. Prospective, randomized trials comparing sacubitril/valsartan to standard therapy are needed to confirm these survival benefits. Similarly, the novel myosin inhibitors ulacamten and aficamten have shown favorable pharmacokinetic and pharmacodynamic profiles in preclinical studies, but their clinical efficacy and safety in dogs with CHF have not been established [12, 14]. These agents are not yet approved for veterinary use, and their availability is limited to clinical trials.

The role of the gut microbiome in canine CHF is an emerging area of research with significant knowledge gaps. One study found that dogs with CHF have overabundance of Escherichia/Shigella and reduced Megamonas compared to healthy controls [15]. Whether these changes are a cause or consequence of CHF is unknown, and the clinical utility of microbiome testing remains speculative. Similarly, the serum peptidomic signatures associated with cardiorenal syndrome in dogs with MMVD are intriguing, but their clinical application for early detection of kidney involvement has not been validated [11].

Clinicians should interpret the available evidence with appropriate caution, recognizing that many recommendations are based on expert consensus and extrapolation from human medicine rather than robust veterinary clinical trials. The dynamic nature of CHF research means that treatment paradigms will continue to evolve as new evidence emerges.

Owner Observation and Preparation for the Veterinary Visit

Owners play a critical role in the early detection and ongoing monitoring of congestive heart failure in dogs. The subtle signs that precede a CHF crisis are often first noticed by attentive owners, and their observations can provide valuable diagnostic information. Preparing owners to recognize these signs and to communicate effectively with their veterinarian can improve outcomes and reduce the risk of emergency presentations.

The most important home monitoring tool is the resting respiratory rate. Owners should be taught to count their dog's breaths per minute when the dog is asleep or resting quietly, ideally at the same time each day. A rate consistently above 30 breaths per minute warrants veterinary attention, and a rate above 40 breaths per minute is an emergency. Owners should be instructed to record these measurements in a log, along with any changes in cough frequency, appetite, activity level, or behavior. This log provides objective data that can help the veterinarian assess disease progression and adjust therapy.

Owners should also be educated about the signs of respiratory distress that require immediate veterinary care. These include open-mouth breathing or panting when at rest, an inability to lie down or rest comfortably, blue or pale gums, and collapse or fainting. Coughing up frothy pink fluid is a sign of severe pulmonary edema and requires emergency intervention. Owners should have a plan for how to transport their dog to the nearest emergency veterinary facility, including having the clinic's phone number and address readily available.

When preparing for a veterinary visit, owners should bring a list of their dog's current medications, including doses and dosing schedules. They should also bring any home monitoring logs, such as resting respiratory rates and body weights. Owners should be prepared to answer questions about the onset and progression of clinical signs, including when the cough started, whether it is worse at night or after exercise, and whether the dog has had any episodes of collapse or fainting. A detailed dietary history, including the type and amount of food and any supplements, is also important.

Owners should be aware that the diagnostic workup for CHF may require multiple tests and may be costly. Thoracic radiography, echocardiography, blood work, and electrocardiography are the standard diagnostic tools, and the total cost can range from several hundred to over a thousand dollars, depending on the geographic location and the complexity of the case. Owners should discuss the expected costs and the diagnostic plan with their veterinarian before proceeding. Some veterinary clinics offer payment plans or accept pet insurance, which can help manage the financial burden.

Owners should also be prepared for the possibility that their dog may need to be hospitalized for initial stabilization. Dogs presenting with acute respiratory distress from pulmonary edema often require oxygen therapy, intravenous diuretics, and close monitoring. The duration of hospitalization varies depending on the severity of the condition and the response to treatment, but most dogs require at least 24 to 48 hours of inpatient care. Owners should discuss the expected duration of hospitalization and the visiting policies with their veterinarian.

Finally, owners should understand that CHF is a chronic, progressive condition that requires lifelong management. Regular veterinary rechecks, typically every 1 to 3 months for stable dogs, are essential for monitoring disease progression and adjusting therapy. Owners should be prepared for the emotional and financial commitment involved in managing a dog with CHF, and they should seek support from their veterinarian, family, and friends as needed.

Prevention and Early Intervention Strategies

Preventing congestive heart failure in dogs requires a multifaceted approach that begins long before clinical signs develop. For breeds predisposed to MMVD, such as Cavalier King Charles Spaniels, Dachshunds, and Miniature Poodles, regular veterinary checkups with auscultation for heart murmurs should begin at an early age. Annual echocardiographic screening is recommended for at-risk breeds starting at 3 to 5 years of age, as early detection of structural heart disease allows for timely intervention.

The most important preventive intervention for MMVD is the use of pimobendan in dogs with stage B2 disease. The EPIC trial demonstrated that pimobendan significantly delays the onset of CHF and prolongs survival in dogs with cardiomegaly but no clinical signs. However, not all dogs with stage B2 disease progress to CHF at the same rate, and the decision to initiate preclinical pimobendan should be based on the severity of cardiomegaly, the rate of disease progression, and the owner's preferences. Dogs with mild cardiomegaly (LA:Ao ratio less than 1.6) may be monitored without therapy, while those with moderate to severe cardiomegaly (LA:Ao ratio greater than 1.6) are more likely to benefit from early intervention.

Weight management is another critical preventive strategy. Obesity increases hemodynamic load on the heart, exacerbates valvular regurgitation, and contributes to the development of pulmonary hypertension. Maintaining a lean body condition score (4 to 5 out of 9) reduces the risk of CHF and improves overall cardiovascular health. Owners should work with their veterinarian to develop a weight management plan that includes portion control, a balanced diet, and regular exercise appropriate for the dog's age and breed.

Dental health is often overlooked as a preventive measure for heart disease, but periodontal disease is associated with an increased risk of infective endocarditis, which can cause valvular damage and lead to CHF. Regular dental cleanings, home dental care (such as brushing or dental chews), and annual oral examinations can reduce the risk of periodontal disease and its systemic consequences.

Heartworm prevention is essential in endemic areas. Heartworm disease (Dirofilaria immitis) causes pulmonary hypertension, right-sided heart failure, and can lead to CHF. Year-round heartworm prevention with a monthly preventive medication is recommended for all dogs living in or traveling to endemic areas. Annual heartworm antigen testing is also recommended to ensure that preventive measures are effective.

For breeds at risk of taurine-deficient DCM, such as Golden Retrievers, Newfoundlands, and Cocker Spaniels, dietary supplementation with taurine and L-carnitine may be beneficial. These breeds should be fed a balanced diet that meets their nutritional requirements, and owners should avoid grain-free or exotic ingredient diets that have been associated with taurine deficiency. Regular echocardiographic screening is recommended for at-risk breeds, even in the absence of clinical signs.

Prognosis and Quality of Life Considerations

The prognosis for dogs with congestive heart failure varies widely depending on the underlying cause, the stage at diagnosis, and the response to therapy. Median survival times reported in the literature range from 155 days for stage D disease to over 1,000 days for stage C dogs treated with newer therapies [8, 19]. However, these numbers represent population averages and do not predict individual outcomes. Some dogs with stage C disease survive for several years with good quality of life, while others with stage D disease may succumb within weeks despite aggressive therapy.

Several factors are associated with longer survival. ACE inhibitor therapy has been shown to prolong survival to cardiac mortality in dogs with CHF [7]. Higher urinary sodium-to-potassium ratio (uNa:K) at presentation is associated with greater improvement in radiographic pulmonary congestion and shorter hospitalization, and dogs that survive to discharge have a higher uNa:K than those that die during hospitalization [2]. Normal serum chloride concentration is associated with lower neurohormonal activation and better outcomes [3]. Good diuretic responsiveness, as measured by urine sodium concentration, is also associated with longer survival [4].

Factors associated with shorter survival include hypochloremia, low uNa on chronic diuretic therapy, development of azotemia (cardiorenal syndrome), pulmonary hypertension, and arrhythmias [3, 4, 11, 19]. Dogs that require preclinical pimobendan and then develop CHF have shorter survival from the onset of CHF compared to pimobendan-naive dogs, reflecting more aggressive disease [5].

Quality of life is a paramount consideration in the management of CHF. Owners should be counseled that the goal of therapy is not simply to prolong life, but to maintain a good quality of life for as long as possible. Quality of life assessment should include evaluation of the dog's appetite, activity level, ability to rest comfortably, and interaction with family members. The presence of persistent cough, respiratory distress, or abdominal distension significantly impairs quality of life and may indicate the need for therapy adjustment or palliative care.

Owners should be prepared for the possibility of sudden decompensation, even in dogs that have been stable for months. The transition from compensated to decompensated CHF can occur rapidly, often triggered by factors such as dietary indiscretion, stress, or concurrent illness. Owners should have a plan for emergency care and should know when to seek immediate veterinary attention.

End-of-life decisions are difficult but necessary. Owners should discuss their dog's prognosis and treatment options with their veterinarian, and they should consider their dog's quality of life when making decisions about continued therapy. Euthanasia may be the most humane option for dogs with refractory CHF that are experiencing significant respiratory distress, pain, or suffering. Owners should be supported in this decision and should be assured that they have provided the best possible care for their beloved companion.

Special-Population Considerations in Canine CHF

The management of congestive heart failure in dogs requires consideration of special populations, including puppies, geriatric dogs, dogs with concurrent diseases, and dogs with atypical presentations.

Puppies and Juvenile Dogs: CHF in puppies is most commonly caused by congenital heart defects, such as patent ductus arteriosus, subaortic stenosis, pulmonic stenosis, or ventricular septal defects. These conditions may present with signs of heart failure in the first few months of life. Myocarditis caused by canine parvovirus can also cause acute heart failure in neonatal puppies, with histopathological findings including myocardial necrosis and inflammation [18]. The diagnostic approach in puppies includes echocardiography to identify structural abnormalities, and treatment may involve surgical correction or interventional catheterization for amenable defects. Medical management with diuretics and inotropes may be used as a bridge to definitive therapy.

Geriatric Dogs: The majority of dogs with CHF are geriatric, with MMVD being most common in small-breed dogs over 8 years of age. Geriatric dogs often have concurrent diseases, such as chronic kidney disease, osteoarthritis, or cognitive dysfunction, that complicate CHF management. The presence of chronic kidney disease is particularly challenging, as loop diuretics can worsen renal function, and ACE inhibitors may cause hyperkalemia. The cardiorenal syndrome is a common complication in geriatric dogs with CHF, characterized by progressive renal dysfunction secondary to reduced cardiac output and neurohormonal activation [11]. Serum peptidomic profiling may help identify dogs at risk for cardiorenal syndrome, but this testing is not yet widely available [11]. Geriatric dogs may also be more sensitive to the side effects of medications, such as hypotension from vasodilators or electrolyte imbalances from diuretics. Dose adjustments and more frequent monitoring are often necessary.

Dogs with Concurrent Diseases: Dogs with CHF may have concurrent conditions that affect treatment decisions. Hyperthyroidism, though rare in dogs compared to cats, can cause secondary cardiomyopathy and exacerbate CHF. Thyroid function testing should be considered in dogs with unexplained tachycardia, weight loss, or poor response to therapy. Hypertension is common in dogs with chronic kidney disease and can worsen CHF by increasing afterload. Blood pressure monitoring is recommended, and antihypertensive therapy (e.g., amlodipine) may be indicated. Diabetes mellitus requires careful management, as some heart medications (e.g., beta-blockers) can mask the signs of hypoglycemia. Obesity increases hemodynamic load and should be addressed through dietary modification and exercise, but weight loss should be gradual to avoid muscle wasting.

Dogs with Atypical Presentations: Not all dogs with CHF present with the classic signs of cough and tachypnea. Some dogs, particularly those with right-sided CHF, may present with abdominal distension (ascites) as the primary complaint. Others may present with syncope or collapse due to arrhythmias or hypotension. Dogs with pleural effusion may present with rapid, shallow breathing and muffled heart sounds on auscultation. The diagnostic approach should be tailored to the presenting signs, and a high index of suspicion is necessary to avoid missing the diagnosis.

Breed-Specific Considerations: Certain breeds have unique considerations in CHF management. Cavalier King Charles Spaniels are predisposed to MMVD and may develop CHF at a younger age than other breeds. Doberman Pinschers are predisposed to DCM and may present with acute collapse or sudden death due to ventricular arrhythmias. Boxers are predisposed to arrhythmogenic right ventricular cardiomyopathy, which can cause syncope and CHF. Great Danes are predisposed to DCM and may have concurrent taurine deficiency. Golden Retrievers and Newfoundlands are at risk for taurine-deficient DCM and may benefit from dietary supplementation. Owners of these breeds should be educated about the specific risks and screening recommendations.

Dogs with Refractory CHF (Stage D): Stage D CHF is defined by the need for high-dose diuretics (furosemide > 8 mg/kg/day or equivalent torasemide dose) and is associated with a median survival time of 155 days [19]. These dogs often have pulmonary hypertension, arrhythmias, and cardiorenal syndrome. Management may require combination diuretic therapy (e.g., furosemide plus spironolactone or hydrochlorothiazide), positive inotropes (pimobendan), and vasodilators (ACE inhibitors or sacubitril/valsartan). Thoracocentesis may be needed for pleural effusion, and abdominocentesis for ascites. Quality of life assessment is critical, and palliative care options should be discussed with the owner. Euthanasia may be the most humane option when medical therapy is no longer effective.

Frequently Asked Questions

1. What is the life expectancy of a dog with congestive heart failure? Life expectancy varies widely depending on the stage at diagnosis, underlying cause, and response to therapy. Median survival from first CHF episode ranges from 168 days in dogs with aggressive disease to over 1,000 days in stage C dogs treated with newer therapies like sacubitril/valsartan [5, 8].

2. Can congestive heart failure in dogs be reversed? CHF is generally not reversible, but it can be managed. In rare cases (approximately 0.2% of dogs with MMVD), dogs may achieve clinical stability allowing withdrawal of diuretics, suggesting some reversibility of the congested state [1].

3. What are the final stages of congestive heart failure in dogs? Stage D (end-stage) is characterized by refractory CHF requiring high-dose diuretics. Dogs may have persistent cough, severe dyspnea, ascites, muscle wasting, and poor quality of life. Median survival in stage D is 155 days [19].

4. How do I know if my dog is in heart failure? Key signs include a persistent cough (especially at night), rapid breathing at rest ( > 30 breaths per minute), exercise intolerance, restlessness, and abdominal distension. A veterinary examination with chest X-rays and echocardiography is needed for definitive diagnosis.

5. Is congestive heart failure painful for dogs? CHF itself is not typically painful, but the associated respiratory distress (dyspnea) causes significant discomfort and anxiety. Dogs with CHF may appear restless, anxious, or unable to get comfortable.

6. What is the best food for a dog with congestive heart failure? Veterinary therapeutic diets formulated for heart disease (e.g., Hill's Prescription Diet h/d, Royal Canin Veterinary Diet Cardiac) are recommended. These diets are low in sodium, moderate in protein, and supplemented with taurine, L-carnitine, and omega-3 fatty acids.

7. Can a dog with congestive heart failure fly on an airplane? Most airlines require a veterinary health certificate and may not accept dogs with known CHF due to the risk of in-flight decompensation. The stress of air travel and changes in cabin pressure can exacerbate respiratory signs. Consult with your veterinarian and the airline before traveling.

8. How often should a dog with congestive heart failure see the veterinarian? Dogs with stable CHF should be rechecked every 1-3 months for physical examination, blood work, and imaging. Dogs with decompensated CHF or stage D disease may need weekly or biweekly monitoring.

Related Veterinary Guides

• Myxomatous Mitral Valve Disease in Dogs: Staging and Management
• Canine Dilated Cardiomyopathy: Diagnosis and Treatment
• Pulmonary Edema in Dogs: Causes and Emergency Management
• Cardiac Biomarkers in Veterinary Medicine
• Veterinary Echocardiography: A Practical Guide
• Chronic Kidney Disease in Dogs: Staging and Management
• Heartworm Disease in Dogs: Prevention and Treatment

References

[1] Hsueh T, Chan IP, Yang CC et al. Rare stability in dogs with myxomatous mitral valve disease: Clinical observations of loop diuretic withdrawal after congestive heart failure. Open Vet J. 2026. https://pubmed.ncbi.nlm.nih.gov/42375430/

[2] Cho J, Kim M, Choi M et al. Spot urinary electrolytes are associated with decongestion and duration of hospitalization in dogs with acute left-sided congestive heart failure secondary to myxomatous mitral valve disease. Am J Vet Res. 2026. https://pubmed.ncbi.nlm.nih.gov/42385769/

[3] Adin D, Qu Y, Domenig O et al. Influence of serum chloride concentrations on the renin-angiotensin-aldosterone system in dogs with congestive heart failure. Am J Physiol Renal Physiol. 2026. https://pubmed.ncbi.nlm.nih.gov/42324236/

[4] Rollins A, Adin DB, Crooks AV et al. Urine sodium concentration and diuretic responsiveness in dogs receiving orally administered loop diuretics for chronic congestive heart failure. J Vet Intern Med. 2026. https://pubmed.ncbi.nlm.nih.gov/42302767/

[5] McAulay G, Hills M, Dukes-McEwan J et al. Survival of dogs with myxomatous mitral valve disease administered preclinical pimobendan in comparison to pimobendan-naïve dogs from the onset of congestive heart failure. J Vet Cardiol. 2026. https://pubmed.ncbi.nlm.nih.gov/42247930/

[6] Patata V, Porciello F, Rishniw M et al. Diagnostic accuracy of right pulmonary vein-to-pulmonary artery ratio to identify congestive heart failure in dogs affected by myxomatous mitral valve disease. J Vet Cardiol. 2026. https://pubmed.ncbi.nlm.nih.gov/42114320/

[7] Masters AK, Mochel JP, Cai J et al. Prognostic value of plasma cortisol concentration in dogs with congestive heart failure. J Vet Intern Med. 2026. https://pubmed.ncbi.nlm.nih.gov/41964610/

[8] Carlson JA, Stern JA. Long-term sacubitril/valsartan is well tolerated in dogs with heart failure and myxomatous mitral valve disease and suggests excellent survival benefits. Am J Vet Res. 2026. https://pubmed.ncbi.nlm.nih.gov/41985537/

[9] Yang R, Cronin C, Qanud K et al. MRS2339, a cardiac P2X4 receptor nucleotide activator, improves systolic function in heart failure. Med Chem Res. 2026. https://pubmed.ncbi.nlm.nih.gov/42446539/

[10] Wang YX, Santos EW, Mistretta S et al. Type-1 Ryanodine Receptor Plays an Important Role in Cardiac Hypertrophy and Heart Failure by Increasing Type-2 Ryanodine Receptor-Mediated Calcium Release. Int J Mol Sci. 2026. https://pubmed.ncbi.nlm.nih.gov/42196272/

[11] Pichayapaiboon P, Ploypetch S, Sakcamduang W et al. Serum peptidomic profiling and peptide mass fingerprinting reveal signatures associated with peroxisomal and mitochondrial pathways in MMVD-associated cardiorenal syndrome in dogs. PLoS One. 2026. https://pubmed.ncbi.nlm.nih.gov/42139248/

[12] Grillo MP, Zamora J, Easterday AN et al. In vitro and in vivo preclinical pharmacokinetic characterisation of ulacamten, a small molecule cardiac myosin inhibitor for the treatment of heart failure with preserved ejection fraction (HFpEF). Xenobiotica. 2026. https://pubmed.ncbi.nlm.nih.gov/42083784/

[13] Thepsupornkul K, Surachetpong SD, Kunapinun A et al. Canine radiography and echocardiography sensor fusion for deep learning-based detection and classification of myxomatous mitral valve disease. J Thorac Dis. 2026. https://pubmed.ncbi.nlm.nih.gov/42444957/

[14] Sárkány F, Priksz D, Juhász B et al. Myofilament-level effects of aficamten increase diastolic chamber volumes and maintain cardiac output through preserved length-dependent force generation in healthy rat and canine myocardium. Basic Res Cardiol. 2026. https://pubmed.ncbi.nlm.nih.gov/42362932/

[15] Cimerman M, Papić B, Nemec Svete A et al. Exploratory analysis of gut microbiota and its association with peripheral blood immune cell populations in canine myxomatous mitral valve disease. BMC Vet Res. 2026. https://pubmed.ncbi.nlm.nih.gov/42304343/

[16] Kırkulak T, Engin ŞC, Erdoğan S. Thoracic Radiographic Evaluation of Canine Dilated Cardiomyopathy: An Anatomical Perspective. Anat Histol Embryol. 2026. https://pubmed.ncbi.nlm.nih.gov/42136132/

[17] Hiraki N, Morita H, Nakamura Y et al. Understanding the hemodynamic effects of milrinone in normal and failing hearts: an experimental study using the circulatory equilibrium framework in canines. Am J Physiol Heart Circ Physiol. 2026. https://pubmed.ncbi.nlm.nih.gov/41830479/

[18] Jarolmasjed S, Ghorani M, Shahbazfar AA et al. Fatal Myocarditis Caused by Canine Parvovirus in a Litter of One-Day-Old German Shepherd Puppies: Molecular and Histopathological Findings. Vet Med Sci. 2026. https://pubmed.ncbi.nlm.nih.gov/42233361/

[19] Oricco S, Crosara S, Mazzoldi C et al. Clinical findings and survival time in dogs with myxomatous mitral valve disease at the American College of Veterinary Internal Medicine stage D. J Vet Cardiol. 2026. https://pubmed.ncbi.nlm.nih.gov/42225449/

[20] Leão J, Winck VL, Barnet LS et al. From prototype to veterinary patient: a pharmacokinetic clinical trial of 3D-printed pimobendan tablets in beagle dogs. Drug Deliv Transl Res. 2026. https://pubmed.ncbi.nlm.nih.gov/42184094/