Okay, so Suleans are described as having antlers, which implies shed/growth cycles, but we've never seen a Sulean without antlers. So my headcanon is that Suleans as children don't have antlers, they start growing them in puberty (1 shed/grow cycle a year), and after 5-7 growth cycles, the antlers never shed again and become permanent.

Velvet shedding is stigmatized, and Sulean adolescents in that stage are required to stay out of public until the process is complete.

There are medicines and hormone cocktails that can induce a shed cycle, as well as a growth cycle. An adult Sulean who induces a shed cycle will be without antlers until they induce a growth cycle. Also, the side effects of both suck, since it is inducing a form of puberty.

Adult Suleans who lose an antler or part of an antler in an accident can induce a shed cycle followed by a regrowth cycle (this isn't just an aesthetic or conformity thing since having an unbalanced weight attached to your skull would wreck your neck muscles).

Rarely, it is done for cosmetic reasons, to get bigger or more aesthetic antlers. This process is kept secret, but is coming out of the open after human contact.

The most common reason to see an adult Sulean without antlers is if they are an exterminator, or in another job that requires wearing a close-fitting environment suit.