Background: Hospitalization for children often involves stress induced by fear and pain. Complementary therapies, such as Animal Assisted Activities (AAA) with dogs, can alleviate the hospital experience. Purpose: The first aim of this study was to initiate the development of an instrument that measures healthcare professionals' attitudes toward complementary therapy, specifically dogs in AAA. The second aim was to elucidate the emerging effects of introducing dogs to children in healthcare settings, as reported by healthcare professionals. Materials and methods: A questionnaire covering demographics, rating attitudes, and allergy and hygiene risks, followed by open-ended questions, was completed by 61 healthcare professionals (HCPs). Quantitative data were analysed statistically, while qualitative data underwent content analysis. Results: The Attitude Instrument of Complementary Therapy (AICT) included 7 items and was evaluated using exploratory factor analysis. Healthcare professionals had a median score of 25 (range 18-28), high scores indicating a more positive attitude. However, 36 % of the HCPs perceived a risk of allergies, and this group had a significantly lower median score, 22 versus 26. Open-ended answers were analysed into four categories: "Dogs could positively affect children in hospital", "Dogs may pose a risk of allergies in children", "Dogs might be frightening for children" and "Dogs can affect healthcare professionals' working situation". Conclusion: The AICT can serve as a valuable tool for investigating HCPs' attitudes to dogs in AAA as complementary therapies. Professionals view dogs as beneficial for hospitalized children, but attitudes toward dogs working in paediatric care can be influenced by concerns about risks such as allergies.