Vertigo
Elderly dogs are susceptible to an unusual form of intense vertigo, the cause of which is unknown; the affected dog is unable to stand up and remains sprawled on the floor, the eyes displaying intense nystagmus, for typically a few days. While terrifying in appearance, owners often fearing that the dog has had a fatal stroke (which is actually uncommon in dogs), the vertigo passes within a few days and by the end of a week the dog is staggering around upright, and within another week there is no evidence that anything at all had happened. The only risk of the disease is that the dog is unable to eat or drink in that condition, and must receive supportive therapy of intravenous fluids and nutrition; a light sedative is usually also administered, as the dog naturally seems terrified during the experience.