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Echocardiographic findings in 103 cats with hyperthyroidism
B R Bond1, P R Fox, M E Peterson
1Department of Medicine, Animal Medical Center, New York, NY 10021.
Summary
Hyperthyroidism in cats commonly causes reversible heart muscle disease (cardiomyopathy). While treatment often improves cardiac abnormalities, some cats may experience persistent issues, suggesting underlying conditions.
Area of Science:
- Veterinary Cardiology
- Endocrinology
Background:
- Feline hyperthyroidism is a common endocrine disorder.
- Thyrotoxicosis can lead to significant cardiovascular changes, known as thyrotoxic cardiomyopathy.
Purpose of the Study:
- To investigate cardiac abnormalities in cats with untreated hyperthyroidism using M-mode echocardiography.
- To evaluate the long-term effects of treatment on thyrotoxic cardiac disease in cats.
Main Methods:
- M-mode echocardiography was performed on 103 cats with untreated hyperthyroidism.
- Follow-up echocardiography was conducted on 24 cats after treatment (thyroidectomy or radioiodine).
Main Results:
- Left ventricular caudal wall (71.9%) and interventricular septum (39.8%) hypertrophy were common abnormalities.
- Hyperthyroidism often led to increased left atrial diameter (70.0%) and enhanced contractility indices.
- Treatment resulted in resolution or improvement of left ventricular hypertrophy and hyperdynamic wall motion in most cats.
Conclusions:
- Feline hyperthyroidism is frequently associated with largely reversible cardiomyopathy.
- Persistent or worsening cardiac abnormalities after treatment may indicate primary cardiomyopathy or lasting thyroid hormone-induced damage.