A method of preparing a canine antibody suitable for use in the therapeutic treatment of a canine is provided. In particular, there is provided immunoglobulins which can be selected for the characteristic of whether they mediate downstream complement mediated immune activation when bound to a target antigen. Canine derived antibodies comprising specific heavy chain isotypes are provided. The invention extends to the use of the immunoglobulins of the invention in methods of treating conditions such as pain, inflammatory conditions and cancerous conditions in a canine.