A genetic predisposition is suggested by an HLA- DQB1 0301 allele association with haplotypes DQB1 0302, 0303 and 06, and especially the DRB1 1101 DQB1 0301. side effects of doxycycline in dogs This adverse reaction is more common during long- term use of the drugs of the tetracycline- class, but it has been observed following repeated short- term courses.