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Hyperthyroidism

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Cats

About this condition

A condition of excess thyroid hormone production that accelerates metabolism, and the most common endocrine disorder in cats over 10 years of age. Signs include weight loss and increased activity; untreated, it puts increasing strain on the heart and kidneys.

Common symptoms

  • Weight loss despite a good appetite
  • Increased activity and restlessness
  • Vomiting, loose stools, or diarrhea
  • Unkempt or dull coat

Common causes

  • Benign thyroid hyperplasia or adenoma (most common)
  • Aging (most common in cats over 10 years)
  • Environmental and dietary factors (details under ongoing research)
  • Thyroid malignancy (rare)

Prevention (husbandry & daily care)

Semi-annual health check-ups including thyroid hormone testing are recommended for cats over 10 years old. Early detection minimizes the burden on the heart and kidneys.

Related species guide

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When to see a vet

Consider a vet within a few days

What treatment does a vet provide?

Veterinarians measure total thyroxine (T4) levels through blood tests to confirm the condition and assess cardiac and renal impacts. Management options discussed include oral medication, radioactive iodine therapy, and surgical thyroid removal.

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