Pyganic Pro is labeled for use on animals and livestock on a dairy farm as well as many other places. This is the verbiage from the product label:
FOR USE IN BARNS, DAIRIES, MILKING PARLORS, MILKING ROOMS AND POULTRY HOUSES: To kill the following flying insects: Flies, Fruit Flies, Gnats and Small Flying Moths, dilute at the rate of 2.5 fluid ounces per gallon of water. Apply as a fog or fine mist (at approximately 2 fluid ounces per 1,000 cubic feet of space), directing the nozzle for maximum coverage and above livestock and poultry toward the ceiling and upper corners of the area being treated. For best results, close doors and windows before spraying, and keep them closed for 10 to 15 minutes. Applicator should vacate the treated area and ventilate it prior to returning. Sweep up and destroy fallen insects.
Pyganic Pro has up to a 5 year shelf life from the manufacture date if kept out of extreme temperatures and direct sunlight. If the product is exposed to direct sunlight for a long period of time, it will start to lose it's efficacy. It is possible that if the product was left out in the sun, it will not work as well if at all.