Environmental and dietary risk factors for the development of canine atopic dermatitis (CAD) in the high-risk breeds of boxer, bullterrier and West Highland white terrier were assessed in a case–control study. A logistic regression model was developed to evaluate their relative importance in 58 cases from 12 practices in Sweden and 61 unaffected controls, matched to cases by breed and year of birth. The final model included a random error term for ‘examining veterinarian’, as dogs from the same practice were not considered independent. No effect of gender, season of birth, environment, vaccination or de-worming practices on the odds of developing CAD was detected. The main finding was that feeding a diet including noncommercial products to the bitch during lactation had a protective effect on the development of CAD in her offspring; the odds of developing CAD were twice as high among offspring from bitches that were not exposed to home-made/noncommercial diets [95% confidence interval (CI) of the odds ratio: 1.2–3.8]. The population attributable fraction for not feeding home-made diets to the lactating bitch was estimated as 0.4 (95% CI: 0.04–0.63). Randomized controlled clinical trials are needed to further support the finding of a potential protective role of diet in CAD development.