Discloses caninised and chimeric antibodies and antigen binding fragments thereof which bind specifically to canine tumour necrosis factor alpha and inhibit the ability of canine TNF to bind to the TNFR1 receptor. These caninised antibodies have framework regions that do not contain amino acid residues that would be foreign at that position in canine immunoglobulin. The disclosure further extends to nucleic acids encoding same and to methods of treating chronic inflammatory disease such as arthritis in a canine using said antibodies and/or nucleic acids.
