Anything that affects the mouth, nose and/or windpipe can cause a dog to snore. This includes but is not limited to:
Rhinitis -
This term refers to swelling and inflammation in the nasal passageways. It may be due to allergies or an upper respiratory infection. Treatment will vary on the root cause.
Dental problems -
The oral and sinus cavities are connected and therefore if there are dental issues that are causing swelling, this can radiate to the nasal area and cause snoring. Issues can include infection or abscess and these are considered quite serious. Infection left unchecked can spread throughout the entire body.
Fungal disease - There is a type of fungus found in piles of grass clippings from the yard or garden and other similar types of environments that can harbor the Aspergillosis fungal disease. This often begins with snoring and can escalate into sneezing, having a swollen nose, nasal pain and/or
nasal discharge. It is treated with anti-fungal medications.
Foreign bodies or tumors -
Sudden onset snoring can be a simple matter of a small object being stuck in one of the nostrils. And less likely, but possible would be a growth or tumor.
Misaligned jaw or tension in the jaw muscles-
With an older Yorkshire Terrier, the issue of a misaligned jaw would most likely have already been discussed by the veterinarian. For those with puppies that snore loudly, this is something that you will want to have ruled out as a possible cause.
Elongated soft palate -
This is much more common with brachycephalic breed (flat faced), however it can be seen with any breed. This refers to the soft tissue in the back of the throat. If it is too large, the tissue can overlap causing both breathing problems during the day and snoring at night.
Stenoic nares -
Also an issue more typically seen with flat-faced dogs, this refers to the nasal openings being too small for air to properly pass through. It is not uncommon for the openings to be slightly swollen during the teething phase and if so, they will most often revert back to normal afterward.
Sleep apnea -
While not overly common with the Yorkie, this is a possible cause for sleeping issues that include not getting enough deep REM sleep and snoring throughout the night. With this condition, a dog suffers from episodes of interrupted breathing. You may notice that he snores and also becomes startled; briefly waking up before settling back down again.
Light snoring is often a matter of slight irritation to the throat and nose or it is due from positioning.