Salty, a 3-year-old medium-size retriever mix, woke up last week and began making a strange bobbing motion with her head. She seemed completely fine otherwise, and had never exhibited anything like this before, but her owners were worried. I was just finishing up with a big Bernese mountain dog when they called. “Give me a few minutes, then have them come right over,” I told my staff. In the meantime, the owner emailed me a short video clip of the behavior. This is always helpful when a pet does something at home that disappears at the vet’s office. Coughing. Limping. Head-bobbing. Anything unusual but intermittent. Try to take a quick video for the doctor, so we can see exactly what you are seeing at home.
I was glad to have that video when Salty arrived, since her head bobbing had completely stopped. Her physical exam and behavior were unremarkable. No fever. No neurological abnormalities. The picture of health.
People frequently bring dogs in with a complaint of tremors or shivering. Sometimes this is not an indication of disease. Dogs (and people) shiver when cold or frightened. Dogs (and people) may twitch when asleep and dreaming. Elderly dogs (and people) may tremble due to age-related muscle weakness. But Salty was not cold, frightened, asleep, or elderly. Acute onset of tremors in a young, otherwise healthy dog can be caused by a number of things. In very young pups, we consider congenital issues, but Salty was 3. The owners mentioned that she might have gotten into the neighbor’s compost a few days ago, but they weren’t sure if she ate any. Could that be the culprit? Something she ate?
Ingestion of products containing the artificial sweetener xylitol can cause tremors from hypoglycemia (low blood sugar). Toxins such as snail bait and insecticides can cause tremors when ingested. Chocolate, certain wild mushrooms, moldy food. All these can cause tremors. And sometimes we just call it “garbage toxicity,” a catch-all phrase for when dogs eat rotten things we can’t identify. But in all these situations, the tremors are usually constant, and affect the whole body, not just the head. We also expect other signs such as vomiting, diarrhea, depression, loss of appetite, abdominal pain. Salty? Eagerly eating my liver treats and gazing up at me adoringly, waiting for more.
I suggested blood work to rule out metabolic abnormalities like low blood sugar, low calcium, or electrolyte imbalances, and to assess her liver and kidney function. I also advised a complete blood count (CBC) to check for things like anemia or elevated white blood cells from infection or inflammation. I suspected Salty had a benign condition called canine idiopathic head tremors (IHT) — a conclusion that can only be made as a “diagnosis of exclusion.” In other words, by process of elimination, running tests to rule out other diseases while taking the history and specifics of the case into account. If we come up with no other explanation, then we try to sound smart and call it canine idiopathic head tremors.
I always joke that “idiopathic” means “the idiots don’t know what’s causing it.” That’s basically accurate. IHT is thought to have a hereditary genetic component in certain breeds, including the boxer, Doberman pinscher, English bulldog, and Labrador retriever, but can occur in any dog. Salty’s tremor was an up-and-down nodding, but IHT can also be side to side, or even, occasionally, rotary. Episodes are usually brief, but can last for hours in rare cases. Distracting the dog can often stop the tremors. There are other weird syndromes involving dogs getting the shakes. “Orthostatic tremors” happen in the legs of certain young large-breed dogs like Great Danes and mastiffs when they are standing up. The cause is unknown, but they sometimes require antiseizure medications if the tremors progress. Then there’s Little White Shaker Syndrome. This condition causes whole-body tremors in young dogs. It was originally identified in little white breeds like West Highland white terriers, Maltese, and bichon frisé, and although little white dogs still are the majority of reported cases, it has since been found in other breeds of various sizes and colors. It is thought to be immune-mediated, and usually responds to treatment with corticosteroids.
Should we send Salty to see a neurologist? While I always welcome the input of specialists, I have read many online discussions where neurologists review queries and videos from general practitioners about such cases. Almost invariably, the neurologists say that if the tremors are intermittent and confined to the head, and there are no other symptoms, no workup is necessary. Treatment is also pointless, as no medications reliably eliminate the tremors, which are really just a minor annoyance, and probably bother the owners more than the dogs. I told Salty’s owners that we couldn’t completely rule out the possibility that this was some kind of focal seizure, or even an early precursor of epilepsy, but at this point in time, further diagnostics were unlikely to be helpful.
Salty fit the picture for classic canine IHT. There was just one more question. Since IHT is sometimes stress-related, I asked if there had been any big stressors in Salty’s life lately. Well, yes. A resounding yes. Salty had recently gone from living off-Island, where she roamed freely on a farm, to being on the Vineyard, where she needed to be leashed much of the time. She had a smaller living space than previously, and closer quarters with both other pets and little people. Yes, she might be a little stressed.
Idiopathic head tremors are not life-threatening, and usually do not progress. More than half the time, the tremors eventually disappear spontaneously, perhaps as dogs mature and handle life’s ups and downs better. We agreed the best course of action would be to monitor the situation, increase Salty’s exercise, and try to reduce her stress. I hope Salty will soon adjust and come to love Vineyard life. The picture of health.
