Four copies of the collar board have been put together. Only really three errors in the board design: micro USB pin spacing isn't quite the same as the footprint, regulator footprint had Vin and Vout switched, changed my mind about using the DAC for audio output (using a PWM output now).

Was able to try it on a cow a week ago. Safe to say it was a very interesting experience! Collar design isn't ideal, being top heavy it rotated upside down as she moved around, and it doesn't fit the shape of the neck particularly well. I would definitely redesign the enclosure to not have the square top and to have the majority of the weight at the bottom of the collar (was my original plan).