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Endocrine · Cat

Feline hyperthyroidism: appetite, weight, and activity changes

Older cats that lose weight despite eating, drink more, or become unusually restless should be examined rather than simply fed more.

Compiled by Petwell · Content version 2.2.0

Feline hyperthyroidism: appetite, weight, and activity changes

Educational pet-health and visit-preparation reference. Not a diagnosis, prescription, dosage recommendation or substitute for a veterinarian.

Care & observations

  • Record appetite, weight, water intake, vomiting or diarrhea, and changes in sleep or activity.
  • Offer a calm feeding and resting routine and keep a current medicine list.
  • Arrange a veterinary examination and laboratory testing rather than relying on symptoms alone.
  • Use only the diet or treatment plan selected for this cat and report side effects promptly.
  • 受診時には、食事内容、薬・サプリメント、体重の推移が分かる記録を持参します。

Seek veterinary care now

  • Collapse, severe weakness, breathing trouble, repeated vomiting, or sudden marked confusion.
  • A very fast heartbeat with distress or inability to settle needs urgent assessment.

Contact your veterinarian soon

  • Weight loss despite a good appetite, increased thirst or urination, vomiting, diarrhea, or restlessness.
  • A rough coat or reduced tolerance for handling should be included in the history.

What to avoid

  • Do not start human thyroid medicine or change a prescribed treatment without veterinary advice.
  • Do not assume weight loss is normal aging without an examination.

MAKE YOUR OBSERVATIONS USEFUL

Bring a clear timeline to your vet

For the changes covered in this guide, note when they started, how often they happen, whether they are worsening and how they differ from your pet’s usual routine. List recent diet changes, medicines, travel or possible ingestion in time order. Add photos or a short video only when it is safe and will not delay care.

Open local health records

Sources & editorial context

Migrated from the Pet Vet Reference project with its bilingual content preserved. Cited organizations provide background resources and do not endorse this site. Source-based compilation is not individual clinical review; this page does not claim veterinarian sign-off.

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