Abscesses occur when a bite, scratch or wound becomes infected and pus forms under the skin resulting in a lump. Often the bite or scratch may go unnoticed. Indeed by the time the lump is noticed the bite or scratch which originally became infected may have healed so it is often difficult to establish whether the lump is an abscess or a tumour.
If a bite or scratch can be seen on the lump then it is almost certainly an abscess. An abscess will require the pus to be drained and a course of antibiotics may be needed to treat the infection and so veterinary treatment must be sought. In extreme cases it may be necessary to visit the vet regularly as the pus may need to removed more than once whilst the infection clears.
Some abscesses may burst and this can increase the chances of infection making the hamster very ill. Therefore even if an abscess should burst before you have the opportunity to take the hamster to a vet it is still advisable to seek veterinary advice as antibiotics may still be required to help fight the infection even if drainage of the abscess is not required.
Sharp objects or pieces of food that the hamster stuffs in its cheek pouches may pierce the lining of the pouch and become stuck. This in turn can cause the pouch to become infected and an abscess to occur. This can initially be mistaken for the hamster carrying food or bedding in its cheek pouch as the cheek pouch area is swollen. However, if the hamster seems to continuously have its cheek pouches full it may be that the pouches are impacted or an abscess within the cheek pouch has occurred and veterinary advice should be sought.