My 16 week old puppy (husky x lab weighing 12kg) loves duck necks and I give him 2 or 3 a day; yesterday I placed an order for another 72 necks. Alarmingly I have just watched a YouTube video called '5 Things Raw Feeders Might Not Know' where it mentions them. It says that there are traces of thyroid hormones in necks and that excess amounts of these hormones can lead to hyperthyroidism. She limits her dogs to 2 a week then a 1 week gap. Has anyone heard of this?