Despite controversy about efficacy and contradictory evidence for their use, the popularity of dietary supplements in people continues to increase. The aim of this study was to evaluate the prevalence of nutritional supplement use, and the types of supplements being given to dogs in both profit making, private first opinion practice (PP) and the non-profit organisation, the Peoples Dispensary for Sick Animals (PDSA). A broad ranging nutrition questionnaire was conducted. The objectives and methods were carefully explained to all participating practices and the questionnaire was approved by the University of Glasgow Ethics Committee.

In total 800 questionnaires were completed, 400 by clients attending PP and 400 by clients attending the PDSA. Of clients questioned, 27.2% and 29.8% of PP and PDSA respectively gave supplements to their dogs. The choice of supplement between the two groups was significantly different (p <0.001). The proportion of the type of supplement being given to dogs varied between PP clients and PDSA clients; fatty acids/oils 10.3% PP, 11.5% PDSA; glucosamine and/or chondroitin 10.5% PP, 5.8% PDSA; vitamins 6.8% PP,19.3% PDSA. Of the PP clients, 17.8% provided supplements daily compared to 14.3% of PDSA clients (p=0.017); PDSA clients were 50% more likely to provide supplements on a weekly or monthly basis compared to those in PP. The majority of owners (98.8% PP, 94.2% PDSA) fed their dogs either a commercial or a therapeutic diet suggesting that certain supplements, such as vitamins, are not required as the risk of nutrient deficiency on these diets should be low.

In summary, supplement administration to client owned dogs is common. However, there are marked differences in types of supplement being used and frequency of administration between the two sampled groups. The reasons for this are likely to be multifactorial, but may include economic status, recommendations by vets and owner education. However, the use of vitamin supplementation in animals fed a commercially balanced diet should be questioned. In contrast, fatty acids, which have numerous published benefits, are potentially an underutilised resource in veterinary medicine.