Some of them can be hyperesthetic, especially if they are eating processed (canned or kibble) diets. That equates to a Wind Damp Heat condition, for which I've used versions of San Ren Tang.
Given the age, though, and the small red tongue, I like your idea of Yin deficiency causing an internal Wind, in which case Tian Ma Gou Teng Yin is a good choice. If that helps, then support using Yin tonifying herbs and diets (e.g. a real food fish diet) will likely have preventive value.
Lastly, as a quick fix, the owner can try homeopathic Ignatia, often sold in Canada as Iamara. I'd use 30C strength and try it two to three times daily for a few days. Taper to once daily once results are seen. If nothing happens after five days or so, the owner can just stop
I guess the only other possibility is some sort of trigeminal neuralgia, which is more likely if only one side was involved. For that I use Chai Ge Jie Ji Tang (Bupleurum Clearing Formula). Check the mouth (under sedation, I guess?) to be sure there isn't a rotten tooth causing the sensitivity.
Hope that helps you out! One of those is quite likely the answer!