What's the lifespan and health issues for Maltese terrier mixes?

Thank you for using Petco Pet Education Center, formerly Petcoach! Congratulations on your (potential) new addition! Small dogs can live up to 15 years of age, with some dogs living up to 18 or even 20. It truly depends on any underlying health conditions and how they are managed. In general, mixed breed dogs tend to be somewhat less susceptible to hereditary conditions. However, maltese can be predisposed to heart conditions such as valve abnormalities, ocular conditions such as glaucoma, and allergies. Terriers are a very broad category of breeds, but typically have the same predispositions. Please note that just because a dog is predisposed to something, does not mean that it will have the condition at any point in life. I hope this helps and am happy to answer any other questions you may have!