Abstract: A housing is disclosed for an apparatus for determining pregnancy in animals which includes a pressure activated switch. The housing includes a housing portion formed from integrally molded synthetic plastic which is selected to have a rigidity which varies with the thickness of the material. The handle includes walls which define a chamber for receiving components of the apparatus including a pressure activated switch. The walls are selected to have material thickness sufficient for the walls to be rigid in response to a pressure applied by an operator's hand. A digit engaging portion of one of the walls is provided with a reduced thickness sufficient for the digit engaging portion to flex into the chamber in response to a pressure applied by an operator's hand and returned to a rest position when pressure is withdrawn. The pressure activated switch is included within the chamber and has a pressure activated element opposing the digit engaging portion.