I thought I had defined my photoresistors as analog pins at the top by doing this at the top:
That's the problem with computers. They really are stupid. It doesn't matter what you think. It only matters what you DO.
Try
arduino.pinMode(cowPin, Arduino.ANALOG);
The Arduino knows that cowPin is an analog pin. The arduino instance does not.
Performing an analogRead() on a non-analog pin won't get you good results. Yes, I KNOW that the pin on the Arduino is an analog pin. In the arduino instance, it is NOT. Unless you tell the arduino instance that it IS.