A few years ago our dog licked off all the hair off his front legs, people usually say he must be bored.
We had to take him to the vet because it looked he was getting blind. There was nothing they could do for him except pills for glaucoma.
When I came home I read his bloodtest and he had low thyroid reading. Of course noone had mentioned it.
I started giving him Iodine in his water and the licking stopped and all his hair grew back.
Since then I have read several times that dogs often have low thyroid.
When he died of old age we adopted a 7 year old dog and I give him Iodine 3x a week in his water. Our vet finds it interesting and now he will ask do you still give him iodine, great to have an openminded vet.