I have never witnessed "staggering" in thyroid disorders, and NO NO NO thyroid med should be given without a blood test, periode!! I would first suspect Vestibular Syndrome.

Vestibular syndrome in dogs and cats can be a frightening event for owners, given the set of clinical signs that typically present when their pet is affected by this disease. For the owner or even young veterinarian that has little experience with canine and feline vestibular syndrome, it can often be mistaken for a poisoning, siezure, or
stroke. In some cases of vestibular syndrome, there is an identifiable underlying cause, but in most cases, it is never really understood what set the disease off. When we are not certain of the pathogenesis of a disease process, we tag it with the term, ideopathic, hence the name of the disease, ideopathic vestibular syndrome. To understand the disease and its implications, it if first very important to understand the vestibular system, its functions, and the organs involved.

The vestibular system accomplishes three tasks. First, it contributes to an individualís sense of equilibrium in relation to the force of gravity and thus adds to the subjective sense
motion and spatial orientation. Second, inputs coming from the vestibular system convey information to the body ís muscles and posture. Third, while head and body are in motion, the vestibular system controls eye movements so that images remain steady and in focus. This is called the vestibular-ocular reflex.

If the ear is found to be free of infection, then it must be assumed that the vestibular syndrome is ideopathic in origin, or there is cancer. Since cancer of the vestibular system is quite rare, I only revisit that possibility if the patient does not resolve.