Peer-reviewed veterinary case report
Heart changes in hyperthyroid cats are not just hypertrophic
By Foulex, Pierre et al.·Published in Journal of veterinary internal medicine·2026·Veranex France, France·View original on PubMed →
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Original publication title: Hypertrophic cardiomyopathy is not the sole echocardiographic phenotype associated with hyperthyroidism in cats: a retrospective study in 147 cats (2005-2025).
- Species:
- cat
Plain-English summary
A group of 147 hyperthyroid cats was studied to understand the heart problems they might have, specifically looking at different types of cardiomyopathy (heart muscle disease). Most of these cats had hypertrophic cardiomyopathy (HCMP), but some had a different type called restrictive cardiomyopathy (RCMP). Cats with RCMP showed more severe symptoms, like breathing difficulties due to heart failure. The findings suggest that while HCMP is common in hyperthyroid cats, RCMP is also significant and may indicate more serious hyperthyroidism. Treatment focused on managing the hyperthyroidism and its effects on the heart.
People also search for: cat hyperthyroidism heart problems · cat breathing difficulties · hypertrophic cardiomyopathy in cats · cat heart disease treatment
Abstract
BACKGROUND: A hypertrophic cardiomyopathy phenotype (HCMP) can occur in cats with hyperthyroidism. However, it remains unclear whether other cardiomyopathy phenotypes are also associated with hyperthyroidism in cats. HYPOTHESIS/OBJECTIVES: Describe the epidemiological, clinical, and echocardiographic findings and cardiomyopathy phenotypes in a large sample of hyperthyroid cats. Compare the echocardiographic features of hyperthyroid cats with HCMP to those of a contemporaneous sample of normotensive euthyroid cats with primary hypertrophic cardiomyopathy (HCM). ANIMALS: A total of 147 hyperthyroid cats and 112 cats with primary HCM. METHODS: Retrospective study with review of internal medicine and cardiology service databases (2005-2025). RESULTS: Most hyperthyroid cats (117/147, 80%) exhibited 1 of the 3 cardiomyopathy phenotypes: HCMP (94/147, 64%), restrictive cardiomyopathy phenotype (RCMP; 20/147, 14%), or nonspecific (3/147, 2%). Hyperthyroid cats with RCMP had significantly higher total thyroxine concentrations (median, 154 nmol/L vs 95 nmol/L) and more dyspnea related to congestive heart failure (80% vs 11%) than those with HCMP (P < .01). A gallop sound was detected in 10% of hyperthyroid cats (14/147), exclusively in those with HCMP (10%, 9/94) or RCMP (25%, 5/20). The end-diastolic left ventricular diameter was higher in hyperthyroid cats with HCMP than in those with primary HCM (P < .01). Subaortic septal hypertrophy was more frequent (95% vs 67%) in cats with primary HCM than in those with hyperthyroidism-associated HCMP (P < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: The HCMP is the predominant, but not sole, echocardiographic phenotype observed in hyperthyroid cats. The RCMP is the second most frequent phenotype and may reflect a more severe form of hyperthyroidism.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41742580/