Hello Julian, I'm Dr. Deb.
I recently came online and see that your question about Kaz hasn't been answered. I'm so sorry that you've had to wait for a response,but if you still need assistance, I'd like to help if I can.
When it comes to sneezing, there could be several different possible explanations. Sometimes it not always easy to determine the cause especially if the symptoms have only been present for a few days.
I'm not certain if the issues with her muscles and nerves are related to damage done during her dental procedure but it's also possible that they may be related to the sneezing that she's doing (see #1 below).
1. My concern when a dog this age starts to show the symptoms that you describe is that there may be a nasal mass that is responsible. These dogs can begin with sneezing and the discharge may be clear but will often develop into a mucoid or bloody color over time...much depends on the location of the mass though. If it is in the back of the nose, then the discharge will flow down the back of the throat ....similar to post-nasal drip in humans. If the mass is located more towards the end of the nose, then there will be less drainage down the throat but more discharge from the nose.
Diagnosis is usually made with a combination of MRI and rhinoscopy/biopsy.
These are very slow growing masses; I have seen some dogs live up to a year or more with them before they started showing significant discomfort. Sometimes the face/muzzle starts to deform as the mass enlarges but this doesn't happen in every case. Sometimes they will spread to the lungs but not always.
They are not terribly responsive to chemotherapy or radiation therapy (primarily based on their location).
I will treat these dogs with anti-inflammatory drugs which seem to help for a while. I will also even treat them with Doxycycline which has anti-inflammatory properties which also can help...for a little while, at least.
2. Upper respiratory infection or sinus infection although usually the sneezing produces a green or yellow discharge. Antibiotics are frequently dispensed and improvement is seen within a short period of time.
3. Allergies although these problems usually develop in younger dogs. Still possible if you recently moved or installed new carpeting, etc.
Anti-histamines such as Benadryl (at a dose of 1 mg/lb twice a day) may be useful/helpful although sedation can be a side effect.
4. Nasal mites can cause sneezing but may be difficult to find. Treatment is fairly easy, though, with Ivermectin given every week for three doses.
5. Nasal polyps can cause dogs to sneeze although, again, it may be difficult to prove without additional testing such as rhinoscopy and/or an MRI.
6. Fungal infections can cause dogs to sneeze but usually the discharge isn't clear; it's usually more yellow/mucoid and is not terribly common but it depends on where you live.
7. Infected tooth/oronasal fistula is also a cause but less likely if Kaz recently had dental work done. However, having said that, if dental x-rays weren't done, then an infection might be missed.
I would dearly love to be able to narrow the list down for you but as you can see, this symptom isn't related to just one condition.
I also realize that my answer may not be what you want to hear but I would be doing a disservice to both you and Kaz if I were less than truthful and honest in my response to you. I hope you understand.
I also hope that this is helpful and provides options to consider.; again, my apologies for the delayed reply. Deb