Is cavy a word in the Scrabble Dictionary

Yes, cavy is playable

...and is worth 13 points.

Found in the following dictionaries

Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)

"Cavy" Definition

noun

Any of various similar or related rodents, such as the capybara, coypu, and agouti.
Any of various tailless South American rodents of the family Caviidae, which includes the guinea pig.
Any of several short-tailed rough-haired South American rodents (family Caviidae).
A South American rodent with a sturdy body and vestigial tail.