A 6-year-old spayed Shih Tzu was presented with a one-day history of an acute progressive weakness affecting all limbs. The dog had not showed a similar event previously and had been systemically healthy. The dog was routinely vaccinated and up-to-date on parasite prophylaxis. There was no access to toxins that the owners were aware of and no known traumatic event. However, the owners noted that the dog would frequently jump on and off their bed, occasionally falling when doing so.