Is inflammatory bowel disease in dogs and cats associated with a Th1 or Th2 polarization?

Mucosal immunity involves complex interactions to generate either immune tolerance or active immune responses. An imbalance of pro- and anti-inflammatory cytokines and chemokines that drive the recruitment of immune cells to the intestinal mucosa are a key characteristic of inflammatory bowel disease in humans, where distinctive helper-T-lymphocyte profiles help to discriminate between Crohn's disease and ulcerative colitis. This review evaluates the current veterinary literature to determine whether a Th1/Th2 (and possibly also Th17) polarization also exists in canine and feline inflammatory bowel disease.