A son of U.S. Sen. Jeff Flake and the son's wife have pleaded not guilty to animal cruelty charges stemming from the deaths of 21 dogs last summer.

A Maricopa County Superior Court spokesman says 21-year-old Austin Flake and 21-year-old Logan Flake entered their pleas Thursday.

The Flakes were acting as caretakers at the Gilbert dog-boarding facility where the dogs died June 20 of heat exhaustion in an 8- by 12-foot room.

Logan Flake is the daughter of the facility's owners, Jesse Todd Hughes and Maleisa Maurine Hughes, who were away at the time.

Jesse and Maleisa Hughes are also charged in the case and have already pleaded not guilty.