Is sarcoidosis related to exposure to pets or the housing conditions? A case-referent study.

On the assumption that sarcoidosis could be caused by inhalation of antigens stemming from pets a case-referent study was set up to examine this idea. Thirty-nine patients with biopsy-proven sarcoidosis were compared with 106 sex- and age-matched control persons on the exposure to pets, present and previous, in the households. In addition data on basic housing conditions and smoking habits were collected. No statistical difference in the absolute frequency of dogs, dogs and/or cats or any pet in the two groups was observed counting only pets kept for more than 2 years prior to the year of diagnosis. Equally the basic housing conditions (size, type of and age of dwelling, family size) were identical. There was a tendency of more non-smokers in the sarcoidosis group (46% vs 33%) but the difference did not reach statistical significance. However it cannot be excluded that inhalable antigens stemming from pets initiate sarcoidosis among susceptible individuals.