Abscesses: Abscesses are fluid-filled sacs that form when bacteria or foreign matter becomes trapped in the tissues. They can be caused by injuries, such as bites or scratches from other animals, or by internal infections. Abscesses can occur anywhere in the body, but they are most commonly found on the head, neck, or rump of gerbils.
Tumors: Tumors are growths of abnormal tissue that can be benign or malignant (cancerous). Gerbils can develop a variety of tumors, including skin tumors, mammary gland tumors, and adrenal gland tumors.
Hernias: Hernias occur when an organ or tissue protrudes through a weakened area of muscle or fascia. Inguinal hernias, which occur in the groin area, are the most common type of hernia in gerbils.
Hydrocephalus: Hydrocephalus is a condition in which there is an accumulation of fluid in the brain. This can cause the head to enlarge and can lead to a variety of neurological problems.
Bumblefoot: Bumblefoot is a condition that causes inflammation and swelling of the feet. It is caused by pressure sores or injuries to the feet.
If you notice a sudden large lump on your gerbil's body, it is important to take him to the vet to determine the cause and get appropriate treatment.