Thank you for answering those questions for me.
The vet was correct that facial paralysis can be a side-effect of extracting teeth. There are many branches of facial nerves that run along the top and bottom jaws that can sometimes become injured or irritated during a dental procedure and can lead to partial facial paralysis. Stimulation of these nerves does not cause the slow movements of the eye (though in an upper tooth extraction done in the rear of the mouth, if a dental instrument slips, sometimes it can catch the nerves of the eye - but we're dealing with the lower jaw which does not pose this same risk), the head tilt, the slipping, etc.
While this means that the signs are not all likely to be related to the dental itself, I wanted to get into two types of vestibular disease with you as well. We distinguish a "type" of vestibular disease based on how it originates.
The most common type is a peripheral vestibular disease, which arises from damage or irritation to the middle and inner ear
(and associated nerves) as they connect with the brain
. This CAN cause head tilting, flicking of the eye on the affected side, and balance issues. In younger dogs, this is most commonly caused by a middle ear infection, an overzealous ear cleaning (many vets do perform ear cleanings while they have a dog under anesthesia), disease processes such as hypothyroidism
(less common in younger dogs) and scarier issues like tumors
or trauma to that side of the head.
The far less common type is central vestibular disease, which arises from the brain stem itself. We tend to see the same signs with central vestibular disease, but the causes tend to be a lot more severe, such as inflammation of the brain stem, infection, cancer, and damage to the brain stem.
Your vet may be thinking that since the steroids were successful that you might be dealing with an issue related to inflammation in the brain stem, especially if the initial examination of the left ear looked normal. However, the only way to determine for certain what's going on with the brain is through diagnostic testing such as CT scans, MRIs, and analysis of the cerebrospinal fluid to look at the composition and cells.
As facial paralysis and Horner's syndrome can both be very commonly seen with a middle or inner ear infection, and infection/inflammation in the ear may ALSO show improvement with steroids and antibiotics, I wonder if further examination and possibly x-rays of the ear might be warranted if they have not yet been done. While we certainly would want to rule out central vestibular disease processes with further testing, I would hate to immediately jump to the worst case scenario without thoroughly investigating the more treatable causes.
If you have any follow-up questions or concerns, please hit "reply" to get back with me. Otherwise, I hope this has given you a good starting point for what you should be speaking to your vet about and eliminated the concern that this was directly related to the dental.