The prevalence of diseases suffered by dogs within two weeks of their acquisition from a rescue shelter in Northern Ireland was investigated. A postal questionnaire was completed by 556 people who had purchased a dog from the Ulster Society for the Prevention of Cruelty to Animals (USPCA) to provide information on the diseases suffered by their dog. The majority of the dogs (53.7 per cent) had an ailment the most common being coughing and diarrhoea. Of the respondents who returned their dog to the USPCA, 92 per cent did so because the animal was unhealthy. Stray dogs were more likely to have an ailment than unwanted dogs, specifically coughing, and/or skin problems. More puppies suffered from parvovirus, vomiting, and/or diarrhoea than did juveniles or adults. Adult dogs were more likely to have a cough than juveniles or puppies. There was no association between the sex of the dogs and their ailments.