Successful dietary treatment of aggression and behavioral changes in a dog

A 7-year-old male neutered crossbreed dog was presented for investigation of a 2-year history of worsening aggression and changes in behavior. Complete hematology, serum biochemistry, ammonia, basal cortisol, total thyroxine, ionized calcium, testosterone levels, urine analysis, magnetic resonance imaging, and cerebrospinal fluid were unremarkable. A gluten-free hydrolyzed protein diet trial was attempted. Three weeks after changing the diet, the dog’s behavior normalized and the aggression resolved. Additional blood tests to further investigate potential gastrointestinal pathology showed no signs of gut inflammation or malabsorption; however, a mild or early protein-losing enteropathy was suspected based on elevation in fecal alpha1-proteinease inhibitor levels. Anti-transglutaminase-2 antibodies and anti-gliadin antibodies were both found to be markedly elevated, suggesting gluten hypersensitivity. After the successful dietary trial, the dog experienced two instances of relapse associated with a change in diet. In both cases, he was returned to the initial gluten-free diet again, and the signs of aggression ceased within 4 days on each occasion. This case report describes the complete resolution of aggression and behavioral changes after feeding a hydrolyzed gluten-free diet in a dog with a suspected nonceliac underlying gluten hypersensitivity. Diet modification should be considered a simple and safe attempt of treatment or management of behavioral abnormalities in dogs when other common causes have been ruled out.