Using the basics of the "Inadvertent Whistle" mechanics (NF: 4-2-3-a,b,c or d) seems to make sense in a situation where a dog, fox or any other animal interferes with play, although it's NF: 1-1-6 that gives the authority to the referee and relys on his judgment, "to rule promptly and in the spirit of good sportsmanship, on any situation not covered in the rules".