Congestive Heart Failure (CHF) in Dogs and Cats (NAVLE Notes)
Congestive heart failure (CHF) is a condition in which the heart fails to maintain adequate blood flow, leading to fluid buildup in the lungs, abdomen, or both. Clinical signs, diagnosis, and treatment vary between species.
Classic Case
- Signs:
- General: Cough, exercise intolerance, difficulty breathing, orthopnea (standing with neck extended in dogs, crouched with elevated chest in cats), ascites, harsh lung sounds or crackles, syncope, and restlessness.
- Heart Murmur: May or may not be present.
- Cats: May present with paraparesis and cold pelvic limbs if a saddle thrombus (blood clot) occurs.
Diagnosis
- Etiologies:
- Reduced myocardial contractility, valvular regurgitation, or significant diastolic dysfunction.
- Thoracic Radiography:
- Enlarged heart, dilated pulmonary veins.
- Interstitial to alveolar lung changes in caudodorsal lung fields.
- Echocardiography (when stable):
- Left atrial and/or ventricular enlargement, which may cause pulmonary edema.
- Right atrial and ventricular dilation can lead to ascites.
- Valvular insufficiency or poor contractility.
- Specific for Cats: Hypertrophic or restrictive cardiomyopathy may present with decreased diastolic function and systolic anterior motion of the mitral valve.
FIGURE 1. (A) Lateral and (B) dorsoventral thoracic radiographs of an 8-year-old Doberman pinscher with DCM in CHF. Note the cardiomegaly with a straightened caudal border, prominent left atrium, and tracheal elevation. There is a diffuse alveolar/interstitial pattern in the lung fields with air bronchograms and dilated pulmonary veins.
Treatment
- Acute CHF Management:
- Diuretic: Parenteral furosemide (IM, SQ, or CRI).
- Oxygen Therapy: Cage or nasal oxygen.
- Pimobendan: Positive inotrope and vasodilator.
- Stress Reduction: Sedation if needed.
- Chronic CHF Management:
- Diuretic: Oral furosemide.
- Pimobendan: Used long-term to improve heart function.
- ACE Inhibitors: Reduces afterload and supports heart function.
- Diet: Low-sodium diet.
- Exercise Restriction: To reduce cardiac workload.
Key Points
- Prognosis:
- Recovery from an acute CHF episode can be guarded to good.
- Long-term prognosis depends on the underlying disease process and the response to therapy.
- Monitoring:
- Pimobendan is crucial in both acute and chronic CHF therapy.
- Renal function should be monitored closely during chronic therapy, as it helps to guide diuretic and ACE inhibitor dosing.
NAVLE-Style Practice Questions on Congestive Heart Failure
Question 1
A 12-year-old Boxer presents with a history of coughing, exercise intolerance, and occasional fainting. Radiographs reveal enlarged pulmonary veins and caudodorsal interstitial lung changes. What is the most likely diagnosis?
- A) Pneumonia
- B) Pulmonary hypertension
- C) Dilated cardiomyopathy
- D) Congestive heart failure
Correct Answer: D
Explanation: The clinical history, radiographic findings of enlarged pulmonary veins and interstitial changes, and breed predisposition point towards CHF, commonly seen in Boxers with cardiomyopathy.
Question 2
A dog with congestive heart failure is being treated with oral furosemide and pimobendan. What other therapeutic addition is recommended for chronic management?
- A) Corticosteroids
- B) Beta blockers
- C) ACE inhibitors
- D) Bronchodilators
Correct Answer: C
Explanation: ACE inhibitors are a standard component of chronic CHF management, helping to reduce afterload and alleviate heart strain. Corticosteroids and bronchodilators are not typically indicated in CHF, and beta blockers are used cautiously.
Question 3
A cat presents with hind limb paralysis and cold pelvic limbs. Thoracic radiographs show a significantly enlarged left atrium. What complication is most likely, and what should be addressed in treatment?
- A) Saddle thrombus; anticoagulant therapy
- B) Pleural effusion; diuretic therapy
- C) Pulmonary edema; oxygen therapy
- D) Hypertrophic cardiomyopathy; beta blocker therapy
Correct Answer: A
Explanation: Hind limb paralysis and cold pelvic limbs in a cat with CHF and left atrial enlargement strongly suggest a saddle thrombus. Anticoagulants are used to help prevent further clot formation.
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