Provided are various embodiments relating to anti-IL17A antibodies and IL17Ra ECD polypeptides that bind to IL17A. In various embodiments, such anti-IL17A antibodies or IL17Ra ECD polypeptides can be used in methods to treat IL17-induced conditions in subjects, such as humans or companion animals, such as canines, felines, and equines. Also provided are various embodiments relating to IgG Fc variant polypeptides having one or more amino acid substitutions for reducing binding to C1q and/or CD16. In some embodiments, the IgG Fc variants and/or polypeptides comprising the IgG Fc variants (e.g., fusion polypeptides comprising the IgG Fc variants and the anti-IL17A antibodies and/or IL17Ra ECD polypeptides described herein) may have reduced complement-mediated immune responses and/or antibody-dependent cell-mediated cytotoxicity.