Thank you for the additional information about Nika.
When we have dogs showing these kinds of signs there are a range of issues we have to consider. First, it is worth noting that her ability to close her mouth voluntarily does make concerns like trigeminal nerve paralysis less likely here. But if she is holding the mouth ajar at times, reluctant to eat or let you open her mouth fully, we do have to consider that this could be induced by discomfort and/or nausea. And in that case, we'd have to consider issues of the jaw, the oral cavity and potentially GI issues (if there is nausea causing her signs).
Now I am glad that neither of you have found anything stuck in the mouth. It isn't uncommon for dogs to chew on things that then get stuck either between teeth or in the roof of the mouth. (I have even seen pieces of plants manage to get lodged in the roof of the mouth). When this happens, we'd typically see more of a reaction from the dog as they try to remove the item (ie head tossing, pawing, open/closing the mouth, etc). So, with her additional history, this would be less likely here.
As well, even though dental disease doesn't often cause such dramatic signs in the dog, if on this occasion she did have a severely compromised tooth (perhaps decaying enough that there is nerve pain as well), then it is possible that this would lead her to be reluctant to open her mouth (for both food and examination). So, this would still be a consideration, especially if her teeth are very bad, even though she didn't demonstrate these types of signs prior to her previous dental cleanings.
Furthermore, we can see these types of signs arise if there has been mild muscular trauma to the jaw (ie strain/sprain from playing or if she had gotten her collar caught in her mouth, etc.), or in cases of inflammation/damage to the temporomandibular joint (TMJ, this is the hinge joint that allows the mouth to open/close comfortably). And while you haven't seen any scenarios that could have aggravated the jaw region, I would still consider it here since it commonly causes these signs (especially the open mouth issue you are seeing).
Finally, it is possible to see most of these signs associated with nausea (which can cause the lip licking you are seeing). This is something we do have to consider with her since she is suspected of diarrhea as well. In that case, as I am sure you can appreciate, the potential causes are numerous. But if we wanted to rule out nausea, you could trial her on an antacid (you may have to crush it and syringe it with water if she isn't keen to eat). There are a number of antacids that are available over the counter and pet friendly. I would advise only treating with one, but the two I tend to recommend are Pepcid (LINK
) or Zantac (LINK
) . Of course, you'd want to speak to her vet first if she has any other pre-existing issues or is on any other medications (besides those listed). Furthermore, if nausea is afoot, we often will offer a light/easily digestible diet (ie Rice with any of the following: boiled chicken, scrambled eggs (made with water and not milk), meat baby food (do avoid the ones with garlic powder in the ingredients) or there are also veterinary prescription diets that can be used like Hill’s I/D or Royal Canin’s sensitivity).
Overall, there are a number of causes that could induce these signs with wee Nika. In considering these differentials, we have to appreciate that her behavior is being driven by the underlying condition either inducing oral/jaw based discomfort (my primary concern here) or nausea. And in that case, I would say that while it isn't a 'dangerous' situation, it is not a comfortable one for her. Therefore, if your vet had an appointment space for her today, then it would be worth having her seen sooner to just get this settled for her as soon as possible (since that will likely get her back to eating and herself). But if that is not possible, then we'd want to address the nausea angle (since this can be done safely at home) and tempt her to eat with soft foods like those I've listed until she can be seen.
I hope this information is helpful.
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