Almost certainly for hyperthyroid... so maybe you'll be bit a more somnolescent than usual... or maybe (much more likely?) the single dose will have absolutely no visible effect at all. Or maybe the toxic chemicals that contaminated the drug in India (but were ignored because it's only for cats) are killing your kidney cells as we speak and by Sunday you'll have turned a curious tinge of yellow.
;-)
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1