Vertigo (from the Latin vert(ere) = whirling or turning around) is a type of dizziness, a sense of motion when one is stationary, due to a dysfunction of the vestibular system in the inner ear. It is often associated with nausea and difficulty standing or walking.
“Vertigo is a human description of a feeling; dogs can’t tell us what they’re feeling, so vestibular disease is the term used,” says Beverly Sturges, DVM, associate professor of clinical neurology/neurosurgery at the UC Davis School of Veterinary Medicine.
According to Dr. Sturges, the most frequent cases are referred to as idiopathic or “old dog” vestibular disease because it’s most often seen in older dogs and there’s no obvious cause. “It’s benign; we still have no real understanding why it occurs,” she says. “It’s self-limiting, [requiring] no treatment except supportive care and comforting the dog,” she adds. The second most common cause is infection—especially Rocky Mountain spotted fever—or inflammation.
Dr. Sturges describes two broad categories of vestibular disease: outside the brain, and inside. “When outside the brain, it involves the middle or inner ear and is referred to as peripheral vestibular disease. This type is more treatable, with a better prognosis,” she says, and includes the old-dog syndrome. “Inside the brain means it involves the brain stem and is referred to as central vestibular disease. In small breeds—Maltese, Yorkies, Pugs, Poms—it’s usually caused by a non-infectious inflammation of the brain stem, often referred to as inflammatory brain disease. It occurs mostly in younger dogs [less than] two years of age. In larger breeds, central vestibular disease is usually caused by brain tumors [putting] pressure on the brain stem. Or, sometimes, trauma to the head.” Symptoms of central vestibular disease may be more subtle, with gradual onset.
That frightening eye-darting I saw in Meadow? It’s called nystagmus, a rapid, involuntary eye movement, side to side or, less frequently, up and down. “Nystagmus is not seen in all cases, but [it] is common,” says Dr. Sturges. “It lessens as the dog gets used to the sensation. Nystagmus can be profound in old-dog vestibular disease; a few days, or perhaps one to two weeks later, it’s almost always gone. It’s a reliable symptom: if there’s nystagmus, it’s vestibular disease and not usually a seizure. But you can see a drunken gait—ataxia—and other symptoms without nystagmus and it could still be vestibular disease.”
Diagnosis is based on a description of symptoms, or better yet, actual observation of symptoms. When appropriate, a vet will do a CT scan or an MRI to see if there are tumors or brain swelling. The type of nystagmus observed (horizontal versus vertical) and the direction of the dog’s head tilt (another common symptom) can help a neurologist differentiate between peripheral and central vestibular disease. Other issues involving the inner ear, or ear infection, will be ruled out if symptoms persist.
Treating central vestibular disease in dogs depends on the type and cause. “We’re pretty good now at removing tumors from the brain stem,” says Dr. Sturges. “If there’s inflammation and fluid, that can be drained surgically if necessary. We can prescribe antibiotics or an antifungal. When a vascular cause is suspected—a temporary or permanent lack of blood supply—vestibular issues usually get better on their own,” she says. “Toxins are another possibility. Metronidazole [Flagyl] and a few other medicines can cause toxicity, including vestibular disease; taking the dog off the drug and substituting another can resolve it.”
A sudden onset of acute symptoms and an absence of other physical findings usually mean peripheral vestibular disease. You and your vet may elect to wait a few days to see if improvement occurs before doing extensive diagnostics. After some online research, this was the choice I made for Meadow. Some vets will prescribe corticosteroids to reduce swelling and antibiotics just in case the cause is inside the brain. Ultimately, the final diagnosis of old-dog vestibular disease is made by the self-limiting nature of the symptoms. According to Dr. Sturges, 5 to 10 percent of dogs who experience this problem may have additional episodes.