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Congestive heart failure associated with hyperthyroidism in cats
Insights
Hyperthyroidism in cats can cause congestive heart failure, leading to symptoms like difficulty breathing and poor appetite. Early diagnosis and treatment are crucial but outcomes can be poor.
Area of Science:
- Veterinary Cardiology
- Small Animal Internal Medicine
- Endocrinology
Background:
- Feline hyperthyroidism is a common endocrine disorder in older cats.
- Congestive heart failure (CHF) is a potential sequela of untreated or severe hyperthyroidism.
- This study investigates the clinical presentation and outcomes of hyperthyroid cats with concurrent CHF.
Observation:
- Four cats with confirmed hyperthyroidism presented with signs of congestive heart failure.
- Clinical signs included dyspnea, anorexia, cardiac murmurs (holosystolic apical), and gallop rhythms.
- Physical examination revealed palpable thyroid enlargement and weight loss in all affected cats.
Findings:
- Radiography demonstrated moderate-to-severe pleural effusion, cardiomegaly, and signs of pulmonary venous engorgement/edema.
- Echocardiography revealed cardiac dilation and reduced left ventricular shortening fraction (indicating impaired systolic function).
- Laboratory and ECG findings were consistent with typical feline hyperthyroidism.
Implications:
- Hyperthyroidism should be considered in cats presenting with congestive heart failure, even without typical signs.
- Aggressive management of both hyperthyroidism and cardiac disease is necessary.
- Prognosis for hyperthyroid cats with CHF remains guarded, with significant mortality risk even with treatment.
Abstract:
Hyperthyroidism was diagnosed in 4 cats with congestive heart failure. Dyspnea and anorexia were observed in 3 of the 4 cats. In each cat, a holosystolic left and/or right apical heart murmur was auscultated. In 3 cats, a prominent extra heart sound (gallop rhythm) was auscultated. All cats had a palpably large thyroid lobe(s) and weight loss. The laboratory and ECG changes were similar to those reported for feline hyperthyroidism. Moderate-to-severe pleural effusion and cardiomegaly were detected via radiography in all cats. Some cats had radiographic signs of pulmonary venous engorgement and pulmonary edema. Echocardiography revealed cardiac dilatation and low left ventricular shortening fraction (wall motion) in all cats. Three cats responded initially to cardiac drugs and propylthiouracil or thyroidectomy. One of these died later, presumably from an adverse reaction to propylthiouracil, and the others died from recurrent congestive heart failure (1) or postoperative cardiac arrest (1). One cat did not respond to treatment, and died 2 days after diagnosis.