The manufacturing process in Australia for equine antisera against various venoms/toxins is based primarily on ammonium sulphate precipitation of pepsin-digested IgG, whereby Fc and F(ab′)2fragments are separated. The capacity of the process to remove non-enveloped and enveloped model viruses was assessed using a scaled-down process. Each virus was added to mid-process samples from equine plasma before the material was applied to Hyflo Super-Cel™ filtration followed by Fulmont™ Super A filtration. Samples were analysed pre- and post-filtration and the log clearance of the viruses calculated. The mean clearance factors for viral load of canine adenovirus type II (CAV2), poliovirus type 1 (PV1), infectious bovine rhinotracheitis virus (IBR) and canine distemper virus (CDV) were 5·3 logs, 4·2 logs, 5·7 logs and 4·0 logs respectively. Clearance results as virus is adsorbed to the filtration aids which are removed from the process, thereby demonstrating improved viral safety of equine antisera produced by CSL.