"Max" one of my two male boxers also recently started getting longer fur?? They both had typical short hair, and they both get a bath every Saturday but about two months agao we noticed Max's fur was getting longer. Zeus' fur is still short and drys in half the time it takes for Max's fur to dry. Very Strange?
Genetics & breeding plays a big role in that...Angel has a very short, tight coat, very glossy. Samson has longer fur and it's coarse..Angel came from a breeder that does all the right things, Samson(I suspect) is the result of either a mixed breeding or a BYB...So, look to the parents, grandparents etc..The standard states that a Boxer should have a very short tight coat, hence the need to keep them as inside dogs as well....Keep in mind, if you live in a cold climate, your Boxer will grow a winter coat, come spring, they shed like crazy too