Hypocalcaemia after thyroidectomy in cats: tremors and seizures
13-year-old domestic shorthair cat that underwent bilateral thyroidectomy for hyperthyroidism 48 hours ago. It is restless, rubbing its face with its paws, has facial muscle twitching and tremors, and has just had a generalised seizure.
What is most appropriate now?
chevron_right Show answer and explanation
A. Measure ionised calcium and give slow IV calcium gluconate with ECG monitoring
Correct. This is almost certainly hypocalcaemia from iatrogenic hypoparathyroidism (damage or removal of the parathyroids). Slow IV calcium stops the signs; if bradycardia or arrhythmia appears, the infusion is stopped.
B. IV diazepam and start maintenance phenobarbital
These are reactive seizures: the antiepileptic does not correct the cause and seizures will recur while hypocalcaemia persists.
C. IV levothyroxine for acute post-operative hypothyroidism
Iatrogenic hypothyroidism develops over weeks and does not cause tetany or acute seizures at 48 h.
D. Oral calcitriol alone
Calcitriol is needed for maintenance, but it takes several days to act. It is not adequate as the sole treatment of a hypocalcaemic crisis.
lightbulb Key takeaway
After bilateral thyroidectomy, measure calcium daily for several days. After stabilising with IV calcium, switch to oral calcitriol and calcium and taper gradually, as parathyroid function often recovers. Face rubbing is a typical early sign in cats.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.