We see a few oral issues, some of which is covered on the dental health page in more detail, but we will try give at least an overview of everything.
Of course, there is the well known dental disease that can lead to gingivitis, tooth root abscesses, and potentially osteomyelitis.
But, we can also see abnormal tooth development, stomatitis, ulcerations, tonsillitis, and tumors.
Dental disease. This happens when plaque is allowed to build up over time on the tooth surfaces. Plaque is a combination of saliva, food, and bacteria that is normally found in the mouth cavity all mixed into a hard glue like paste. This paste adheres to the teeth, and allows the bacteria to invade underneath the gum line. This first shows up as gingivitis, then later as periodontal disease and tooth root abscesses. This may also be implicated in the formation of resorptive lesions, but that is not yet known for sure.
Abnormal tooth development. Once in a rare while, we will see young cat who either didn't lose their baby teeth like they should have and have adult teeth growing in next to the baby teeth, or their teeth will be sitting abnormally in the socket, or they might have an extra tooth or two. This is not usually a big issue other than it can result in an area where plaque is more likely to build up and cause dental disease.
Stomatitis. This is one of the worst, most painful diseases that a cat can get. A possible, not guaranteed, cure requires removing all of the teeth. If removing the teeth is not successful or if the owner prefers not to remove the teeth, it can be managed for a few years with high dose steroids and immunosuppressants, but eventually becomes resistant to treatment and cats are euthanized due to chronic severe pain. No one has yet isolated the cause of stomatitis, but they are still working on it. If they ever find the cause, then maybe some day we will have an effective treatment. Stomatitis is a hypersensitivity reaction of the soft tissue in the mouth to the plaque on the teeth resulting in severe swelling and inflammation of potentially all soft tissue regions of the mouth and throat.
Ulcerations. These most commonly appear on the surface of the tongue, but can also be present in the soft tissue of the throat. In most cats, these are a result of being exposed to calici virus, and either not being vaccinated, or not having an adequate protective response to the vaccination. If calici virus is the cause, they will go away on their own eventually, but will be painful in the meantime, and will require supportive care for eating and drinking. Rarely, herpes virus can cause ulcerations in the mouth, but usually only if it is complicated by allergies or stomatitis. Less common, but more severe, is ulcerations in the mouth from systemic uremia. This happens when the kidneys are shutting down in end stage kidney failure, whether chronic or acute. This is a bad prognostic sign.
Tonsillitis. Rare, but once in a while we will see a cat with inflamed enlarged tonsils. This is usually caused either by a severe mycoplasma or bordatella infection, or in some cases, an atypical throat infection such as streptococcus or enterococcus. We tend to need an antibiotic of some kind when we see tonsillitis, and we may even need to swab the tonsils for a culture to find an effective antibiotic.
Tumors. Of course, tumors can be found just about anywhere, and mouth is no exception. The most common type of tumor that we will see arise in the mouth region is squamous cell carcinoma. This is a locally aggressive malignant tumor that doesn't metastasize to other areas of the body, but it is highly aggressive where it is located, and unless it is caught extremely early and the owner is willing to have part of the jaw removed in an expensive and painful surgery, it progresses until we end up euthanizing the cat because they can no longer eat or drink, or because they are in severe pain.