That gunk coming out of your cat's nose could result from a variety of causes. Your first thought may be "upper respiratory infection," and you could be right. However, chronic nasal drainage can indicate dental problems in your cat, too, some of which are quite painful.
Nasal Drainage Appearance
The color and consistency of your cat's nasal drainage can tip you off to the cause of the problem. Nasal discharges come in three basic forms, although your cat can experience more than one at a time. A thin, clear discharge usually doesn't indicate an infection, while a thick yellow or greenish discharge does. Sometimes, your cat's nasal discharge contains blood. Your vet will conduct a complete physical examination and takes a blood sample for testing to determine the cause. She'll look into your cat's mouth for any obvious dental causes.
Besides nasal discharge, other symptoms of feline dental disease include excess salivation, facial swelling, reluctance to eat or an odd way of chewing, mouth pawing, crankiness and decreased activity. If your cat exhibits these symptoms along with nasal discharge, suspect a dental ailment rather than an upper respiratory infection.
A fistula occurs when the tissue wall between the nasal cavity and the teeth is damaged, opening the area between the mouth and nose. According to petMD, most of the time the cavity occurs where "the root of the fourth premolar on the upper jaw enters the palate." Anything going into your cat's mouth, such as food and water, can go back out through this opening through his nose. Signs of a fistula include a thick, yellow chronic nasal discharge, along with constant sneezing and bad breath. Surgery required to close this gap consists of extracting the tooth and closing the space with a skin flap.
A tooth root abscess also causes nasal discharge if the affected tooth is on the upper jaw. An abscess consists of a pus-filled cavity, resulting from infection entering the tooth's root socket. Your kitty's mouth will hurt. Your vet will drain and flush the abscess, along with prescribing antibiotics for combating infection. Depending on the depth of the abscess, the tooth might require removal. Since abscesses generally result from periodontal disease, your vet might recommend a complete dental cleaning and plaque removal for your cat.