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Seen most commonly in the cat. Elderly cats are affected with the average age of onset being 12-13 years.
Clinical signs:
- Weight loss despite polyphagia
- Increased activity, nervousness (approximately 10% will show apathy)
- Polyuria and polydipsia
- Heat intolerance, panting
- Tachycardia >240 bpm
- Poor coat, matted and unkempt
- Palpable thyroid mass often present
Often see a hypertrophic cardiomyopathy due to chronically increased heart rate and activity.
Aetiopathogenesis:
>98% are a functional adenoma of the thyroid gland and many will be palpable.
Treatment:
Surgical removal of the affected thyroid gland(s). If bilateral it is important to preserve at least one parathyroid gland to maintain calcium homeostasis.
Medical treatment:
- Carbamizole: Interferes with thyroid hormone synthesis.
- Radioactive iodine therapy. Useful for intrathoracic thyroid nodules.
Pathophysiology
Signalment
Presentation/Clinical Signs
- Weight loss
- Cardiovascular effects
- Palpable goitre
- Hyperactive
- Polyuria
- Polydipsia
Diagnosis
- T4 Assay
- T4 and TSH assay
Treatment
- Surgical - Thyroidectomy
- Medical - Thiamazole blocks synthesis of T3 and T4.
- Radioactive Iodine