It's possible that they're brothers, but someone on Reddit pointed out that they aren't the same species, so unless there was an adoption that's unlikely:
They're two different species. One is an Oryx and one is a Kudu. That makes it unlikely they're biologically related.It seems like there's another likely gay character in "Zootopia" named Clawhauser. He's a police dispatcher and "is portrayed as camp and effeminate."