Neither.
There is no item that can give your pet Sneezles or Neoflu. The only options are Ferocious Negg or Wheel of Misfortune (random disease) or waiting for the disease on the Wheel of Excitement to change to one of the two that give you Meuka.
For completeness, Poisonous Jelly gives Neomonia and Poisonous Lollypop gives Floppy Tongue. Check
this NeoItems thread for more info on sickening items.