Dental Disease: This includes the teeth in the back! If your vet does not check the molars on your chin, get a new vet! Symptoms include drooling, rubbing at the mouth, not eating as well, smaller poops.
Heart Problems: Many chinchillas have heart murmurs. There is no outward symptom of this, and it is not usually a fatal problem in chinchillas.
Trauma: Chinchillas are prone to broken bones, especially broken legs. This often occurs when they are dropped by children, and usually results in amputation of the limb. Also occurs with use of wire wheels.
GI Stasis/Bloat: This is a life and death situation for your chin, and they should be rushed to a vet right away. Symptoms include lethargy, not eating or pooping, painful bloated belly, cold to the touch (hypothermia). If your chin is experiencing even one of these symptoms go to a vet right away! A few hours can be the difference between life and death.
Fur Rings: Male chinchillas can get fur wrapped around the base of the penis, resulting in infection and circulation issues. This should be checked by the owner when possible.
Fur Chewing: Some chins chew, or barber their fur. You will see small or large areas of short, or missing fur. It can be the result of boredom but often is just a stress response from being a wild animal in a domestic situation. Have your vet check for ringworm if you see bald patches.