Reported from the Ponyville Gazette, apparently Ashleigh Ball, voice actor of Rainbow Dash and Applejack has suffered a vocal injury.  If you are unaware, she is the singer (and flute player) for a band called Hey Ocean!  I would guess that since the band is on tour (and new episodes are rolling out), that her recording duties at Studio B have been completed for Season 2.  Copypasta from the Ponyville Gazette:
Another update on Ashleigh Ball’s band, Hey Ocean!’s twitter feed brings us news that Ashleigh’s vocal injury worse than first thought. Hey Ocean! has cancelled the rest of their Eastern Tour in reaction to the news.
Here is the first update:
EASTERN TOUR CANCELLED so sorry, but we’ve learned that Ash’s vocal injury is worse than anticipated. So sorry, rebooking stuff asap :(
And a follow up:
so sorry to cancel :( we don’t want to let down our fans but my vocal injury is scary and requires rest. We’ll be back soon, sorry! <3 Ash
Ashleigh is the voice of both Rainbow Dash and Applejack on My Little Pony: Friendship is Magic.
We will bring you more news as we hear it.
  • Pacce

    Oh dears.
    I really hope she's able to fully recover. I mean, her entire livelihood is from her voice.

  • plaster

    yeah i do too, who knows if it will cause permanent damage or not?

    of course we don't even know the illness so I can't make any general assumptions on this matter.

    hope she gets 100% soon

  • Anonymous

    and 20% more.

  • Anonymous

    hahahaha ^^