What could be leaking after installing a pet sprayer on a tub?
It sounds like it could either be a cracked breaching piece (between the to taps where the spout screws on)  or it could be the spindles leaking.



There is a o-ring in the spindles that stops water from coming out of the tap casing when the water is on. to check the o-ring take of the handles and cover flange turn the taps on with the sprayer turned off, is water coming out of the taps?



If not you can either cap off the fitting where the spout is connected and turn the water on and try and here/see water leaking or hook a pressure gauge up to the spout connection turn the water on then back off and see if the pressure drops when the water is off showing a leak in the breaching piece. How to pressure test