https://www.vetsurgeon.org/f/clinical-questions/18052/rat-with-gas-filled-lump I saw a rat a week ago with a large swelling just caudal to its mandible on the side of its neck. Felt like an abscess so anaesthetised and lanced the mass. It turned out to be a gas-filled pocket. There was no signs of infection or an other obviousen-USTelligent Community 10https://www.vetsurgeon.org/thread/109110?ContentTypeID=1Thu, 27 Feb 2014 23:42:10 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:606b59b8-8be4-4e14-a243-7bd21248f50fLinda Filshie<p>Gas forming bacteria? Some kind of defect in the trachea?</p><div style="clear:both;"></div>