I would think anything is possible. Long ago we had one that broke out in the mouth and lips and throat area every week or so. I would put him up in the brood box to get the collar off the area and it a day or so it would clear up. Back to the chain and again it would break out. Cleaned everything, sprayed everything, but it kept coming back. The only difference between the two living areas was there were stainless bowls in the brood box. He was allergic to the concrete bowls the best I can tell. Once he had stainless bowls on the chain the problem did not come back. So, and not being a doctor or vet, dogs, just like people, can be allergic to just about anything for whatever reason. Once it has been identified it does make life a little easier. EWO