Feline Radioiodine (I-131) Therapy

Feline Hyperthyroidism

What is it?
Feline hyperthyroidism is the most common endocrine disease in cats, usually affecting those over 7 years old. It happens when the thyroid gland makes too much hormone, speeding up metabolism and causing weight loss, increased thirst, appetite changes, and hyperactivity.

Why it matters
If untreated, hyperthyroidism can lead to serious problems such as heart disease, high blood pressure, kidney damage, and blood clots. Early detection through routine screening gives cats the best chance at a long, healthy life.

Common signs to watch for

• Weight loss despite a good appetite
• Increased thirst and urination
• Restlessness or anxiety
• More vocalizing
• Vomiting or diarrhea
• Poor or unkempt coat

Diagnosis
Veterinarians diagnose hyperthyroidism through physical exams and blood tests that measure thyroid hormone levels. Regular screening is recommended for cats over 7 years old—even if they seem healthy.

Treatment options:

• Radioiodine (I-131) therapy: Gold standard treatment that destroys abnormal thyroid tissue with one simple injection; usually curative.
• Medication: Daily oral or topical drugs to control hormone production.
• Dietary therapy: Special iodine-restricted food (requires strict compliance).
• Surgery: Removal of the thyroid gland in some cases.

Radioiodine (I-131) Treatment - What to expect:

Hospitalization & Aftercare for Radioiodine Therapy

• Before Hospitalization
  • Your cat will have a consultation with one of our Internal Medicine doctors, lab work, urinalysis, and occasionally imaging to check thyroid, kidney, and heart health.
  • This ensures the safest, most effective treatment plan.
  During Hospitalization
  • Cats stay about 4-5 days in our calm, stress-free isolation ward while the radioactive material safely leaves their system.
  • They receive cozy bedding, tv, enrichment, and daily monitoring from our trained team.
  • Most cats tolerate the injection well, it’s a quick injection, much like a vaccine.
  After Returning Home
  • For about 2 weeks, owners follow simple precautions:
    • Limit close snuggle time to short daily sessions.
    • Wash hands after handling your cat or litter box.
    • Store used litter separately as directed until it’s safe to discard.
    • Pregnant women and children should avoid handling the cat during this time.
  • Follow-up bloodwork at 1, 3, and 6 months helps ensure thyroid and kidney values are stable.
  • More detailed, personalized instructions will be provided at your cat’s consultation so you feel fully prepared.

Prognosis
With early diagnosis and proper treatment, most cats return to normal health and live happy, active lives. Radioiodine therapy has a 95–98% cure rate and often gives cats the best long-term outcome.

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