<p>Health anxiety by proxy refers to excessive concerns or preoccupation that a loved one may be suffering from or may acquire a serious illness. Although research with parents suggests that this condition may be highly prevalent, assessment has been limited in terms of attachment figures other than children. Dogs take the role of children in many families and the dog owners and parents show opposing patterns, though the underlying mechanisms are currently unknown attachment between humans and dogs shares important characteristics with the child-parent attachment. Thus, for the first time, we investigated whether health anxiety by proxy is also present in childless dog owners. To this end, we adapted an existing measure of health anxiety by proxy for parents to the situation of dog owners and used the existing parent and adapted dog owner questionnaires to gather data from dog-less parents (<i>N</i> = 204) and childless dog owners (<i>N</i> = 200). Overall, we found comparable distributions of health anxiety by proxy in both subsamples and high internal consistencies for both questionnaires. Interestingly, dog owners reported higher levels of health anxiety by proxy than parents. In both subsamples, health anxiety by proxy was linked to depressive symptoms and health anxiety, with these associations being stronger in parents than in dog owners. Moreover, while health anxiety by proxy and attachment towards children were negatively associated in parents, we found the opposite association in dog owners. Taken together, these findings provide the first evidence for the existence of health anxiety by proxy in dog owners, while suggesting that the phenomenology of the condition may differ between parents and dog owners.</p>