There is growing evidence for trained assistance dogs promoting the health, wellbeing, and quality of life of people in a variety of circumstances, including for those with dementia. Little is known about people with younger (early)-onset dementia (YOD) and family carers. As part of a larger study involving 14 people with YOD matched with trained assistance dogs over a two-year period, we report analyses of interviews with 10 family carers conducted on multiple occasions investigating their experience with an assistance dog. Interviews were recorded, transcribed and subjected to inductive thematic analysis. They told a range of experiences; the good and the challenging. Findings fell into three areas: the human-animal bond; relationship dynamics; and responsibility for caring. Concerns were raised with respect to the resources required of carers together with the financial resources needed to support an assistance dog. The study concludes that trained assistance dogs can play an important role promoting the health and wellbeing of both people with YOD and of their family carers. However, support needs to be in place as the circumstances of the family member with YOD changes and the role of the assistance dog as part of the family also changes. Practical (financial) support of a scheme such as the Australian National Disability Insurance Scheme (NDIS) could be important to sustaining such support.