Hamsters have unique stretchy cheeks. They store food and carry bedding in these stretchy cheeks but can also develop diseases specific to them. Syrian (golden) hamsters are often extensively studied in research facilities for the unique characteristics of their cheek pouches.
All hamsters have cheek pouches. These large pockets are actually evaginations of the oral mucosa and can stretch back to your hamster's shoulders. They are used primarily to carry food from place to place. In the wild, hamsters use their cheek pouches to bring food back to their burrows and their name roughly translates to "mister saddlebags" in the local Arabic dialect where they are from.
Hamsters, like other animals, have two cheeks. Sometimes they stuff both of their cheeks and other times they only stuff one side with food. It is normal for hamsters to carry their food around or back to their beds via their cheeks and often continue to eat even after filling their cheek pouches. Females may even carry or hide their babies in their cheek pouches.
Hamster Cheek Diseases
Cheek pouch abscesses are commonly seen in pet hamsters. These are localized infections that cause pus to buildup in the cheek pouch and can spread to the rest of the body quite quickly. Without antibiotics and sometimes a good cleaning to the cheek pouch with betadine by your exotics vet, the infection will cause your hamster to stop eating, be painful, and cause the infection to spread to the rest of his mouth and eventually his bloodstream. Abscesses occur when your hamster tries to put something sharp in his mouth, if he nicks his face on something in his cage causing a small cut or puncture, or if an overgrown tooth protrudes into his cheek.
Cheek pouch tumors are another commonly seen problem in pet hamsters. Tumors are typically cancerous and usually only affect one of the pouches. They can infiltrate the entire cheek pouch tissue which stretches all the way back to their shoulders. They are typically firm and have a different feel than a pouch filled with food. These tumors (usually squamous cell carcinomas) give your hamster a poor prognosis and are difficult if not impossible to completely remove while still allowing your hamster to eat normally.
Cheek pouch eversion is very rare but does occur. Eversion is when the cheek pouch actually flips out of the mouth. You will see a pink bulge in the corner of the mouth and your hamster may have difficulty eating. Your exotics vet will be able to replace the cheek pouch but it may need to be stitched back into place if it keeps popping out.
Cheek pouch impactions are another uncommon problem but are occasionally seen nonetheless. Sometimes large pieces of food and/or bedding are shoved into your little hamsters cheek pouch and your hamster can't get them out. If an impaction isn't cleaned out it will get infected or abscessed when the food or food particles start rotting in the pouch. Typically hamsters have no problem moving food in and out of their mouths but you should be aware of this issue if your hamster has a large pouch for an extended period of time.
Overall, hamster cheeks are arguably the cutest parts of your hamster. A hamster with full cheeks just makes you want to grin and cuddle up with your tiny, fluffy, friend. By being aware of the potential problems these cheeks can run into you can prevent many future issues with your pet hamster.
For more information on other diseases in pet hamsters check out the Hamster Health: Common Health Problems and Diseases in Pet Hamsters article.