Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.
First, I have to say that I am a wee bit concerned about your lass having nasal discharge from one nostril. The reason is because our infectious agents (ie Bordetella, Para influenza, etc) and our chronic rhinitis cases tend to have nasal signs in both nostrils. To see discharge from just one is more suggestive of a local issue within that specific nostril. And I must note that the majority of causes for one sided nasal discharge in an elderly dog can be quite serious.
In regards ***** ***** that could cause her signs, we do have a few to consider. Commonly we can see this with when foreign bodies (ie grass, seeds, bone, etc) get stuck in the back of the nasopharynx or up the nose. Often the item initially causes irritation and inflammation within the nose, sneezing, and eventually secondary infection appears to cause the discharge you are seeing. Other potential causes would be polyps, fungal infections (asperigillus), tumors of the nose (ie lymphoma, adenocarcinoma), and communicating fistulas connecting that side of the nose with a rotten tooth underneath the nasal cavity (which allows mouth bacteria to infect the nose).
So, in this case, we do have some serious concerns. Now I am glad to see that you have had her nose xrayed. Hopefully, her vet also checked her teeth, flushed her nose and examined the back of her throat at the same time to rule out some of those concerns I noted. In regards ***** ***** xray itself, it would rule out some of the above concerns (ie a big mass present in the nasal cavity --as long as there wasn't too much discharge to obstruct their view) but it won't be sensitive enough to rule out all of our concerns. Xray just won't pick up the more diffuse cancers or issues like fungal infections within the nose. Furthermore, the reason flushing the nostril under GA is so important is because only some foreign bodies (ie metal, some plastics, not plant material) can be seen on xray.
Therefore, with her continued signs and lack of diagnosis, I must say that it would be ideal to consider discussing the potential for her vet to use endoscopy to scope the inside of her nasal cavity. This is one of our favored modes of ruling out fungal infection, foreign material, tumors and polyps as we are able to scope the nasal passageways with a small camera carrying scope. This allows the vet to explore the nasal passages and see exactly what is causing trouble. If the nares are clear of these differentials, then the vet will be in a position to biopsy the tissue (so they can rule out or diagnose those inflammatory rhinitis concerns). And if we can diagnose and then treat the cause of this discharge we can also halt the constant recurrence of bacterial infection arising due to opportunistic bacteria taking advantage of her situation.
Finally, I would just note since you didn't mention any blood work being done, that this would be advisable to do. The reason is because every now and then we can see non-settling infections be due to underlying disease (ie diabetes, Cushing's disease, organ issues, etc) or immunosuppression. Therefore, if you are making no progress on her diagnosis, this is something worth checking for her.
Overall, we have to appreciate that one sided nasal discharge is often secondary to something focal going on within that one nostril. This means that issues like diffuse growths, fungus, and foreign bodies would be more suspect then a chronic non-specific rhinitis. Now you have taken the first step with that xray but if is not given a diagnosis, then it'd be ideal to consider scoping her nose.
Finally just to note, in case this is not an option or you are not keen to do so, then it will be a case of just managing and reducing her signs. This means that when the discharge is snotty (a sign of bacteria), antibiotics would be indicated. And for those other times, it would be advisable to speak to her vet about a dog safe decongestant that will reduce nasal secretions like Bisolvin. These can just keep her comfortable and reduce her signs from this lurking condition.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,
If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need. Thank you and hope to see you again soon! : )