Why Do Jack Russells Shake?

By John Martin - June 9, 2022

Jack Russell Terrier sitting on couch

Shaking is not unheard of among Jack Russells. This breed of dog has a lot of excess energy and they need to shake it off, quite literally, from time to time.

So, shaking and sometimes trembling, is one way to burn that extra energy. But it’s not always a good thing, so you need to know why they are doing it for the sake of their health.

Let’s look at the reasons because some of them may be a cause for worry.

Behavioral Reasons

Apart from letting go of that excess energy, there are some behavioral things that cause Jack Russells to shake. Let’s take a look.

Anxiety and Fear

Jack Russells can get quite anxious if and when you leave them alone for too long. They are family dogs that like to be around their people and not being able to do that can cause anxiety. That might result in shaking.

Anxiety might also be the reason behind their shaking if they have been left hungry for a long time.

You might also see the same thing happen if and when they need to use the loo and have not had the chance to do so in a while.

Apart from anxiety, the other common and expected reason why Jack Russells shake is due to fear. Although this one is not hard to guess.

These dogs are not always very good at showing their fear. Jack Russells are considered to be a “weak breed” but they are not very skilled at exhibiting their weaknesses.

Common reasons for fear, especially when they are outdoors, include bikes or any other vehicles moving past them swiftly. They get startled quite easily when this happens and results in physical symptoms of fear.

You know fear is the reason they are shaking if you see them drastically decrease the speed at which they have been running. A lot of times, Jack Russells tend to sit down and start shaking.

Of course, this is not a big problem that you should worry about but there is nothing wrong with giving them a moment to adjust and comforting them in the meantime.


Excitement is another reason why your Jack Russell might be shaking. Again, this is a reason that you don’t have to worry about too much (or at all).

In fact, you don’t even need to figure out what they are excited about because it is a big part of their nature. These four-legged creatures are known to be affectionate and loyal.

So just existing near their family might cause them to be excited. This is also true for other dogs that they are used to.

Depending on the severity of their excitement, their physical tendency might escalate into shaking and trembling.

Temperature Control and Shedding

Physically speaking, Jack Russells are said to shed moderately. They have a thin coat with short hair which explains why it’s called moderate.

But that’s why they don’t have the ability to keep themselves warm during cold winters. Of course, this is in comparison to some other breeds which have a thick coat or long hair.

These are small breeds that are often adopted because they are friendly and easy to maintain. But if you live in a cold region, they can’t keep themselves warm and end up shaking in the winter.

Like humans, they shake and tremble to generate warmth that keeps them comfortable when the mercury drops.

What you can do to help them is to keep them indoors and get accessories that will keep them cozy in frigid temperatures.

You should also try not to keep them outdoors for too long when it’s chilly.

When you take them out for a walk so that they can do their business, bring them back inside soon enough so that they can get warm again before it gets to the point of shaking.

Clearing Their Skin

Sometimes things get stuck on the skin. Humans take it off with our hands, but dogs don’t always have that opportunity.

Jack Russells try to get them with their teeth, but sometimes that’s not an option. So, they start shaking vigorously to get rid of whatever is stuck in their skin.

This might cause some shedding and that’s only natural. But you have to let them do it unless you are willing to check through their body and help them get the debris off their skin.

Sometimes the debris is nothing but hairs that they have shed but are still clinging to their body.

So, let your dog do one round of getting the debris out and then you can jump in with a brush and help them out or see if it’s something else.

Medical Reasons

Now to the difficult reasons. While these are quite rare, there are medical reasons why your Jack Russell might be shaking.

These are the ones you need to pay attention to because if it gets bad, you should know when to knock on your vet’s door.

Nausea and Stomach Pain

If your dog has been shaking for an unusually long time, you must look into reasons apart from cold weather, excitement and anxiety.

Usually, shaking that is caused by nausea and stomach pain lasts a few days but it is a good idea to take them to the vet to make sure it isn’t a serious health condition.

Meanwhile, keep track of how long they have been shaking for and what they have been eating so that your vet has a better idea while coming up with a diagnosis.


Hypoglycemia is the result of unusual levels of blood sugar in Jack Russells.

In this case, the shaking lasts for about 15 to 20 minutes. It’s not a lethal condition, but if things get bad, your dog might be in trouble.

Once again, this is a condition that requires the attention of your vet.

They can tell you what is going on with your pup and what you can do in terms of containing the symptoms and making a plan for treatment if it’s required.

Wobbler Syndrome

Wobbler syndrome is a disease in dogs that relates to their spines. It can result in episodes of shaking.

This is actually considered to be a dangerous medical condition that requires immediate attention from you and the vet.

This is a neurological condition that is the result of problems in the part of the spine that is near the neck and it is called cervical spondylomyelopathy.

You know this is the case when you see your Jack Russell keeping their head low, walking really slowly and their posture is all wobbly. That explains where the disease got its name from.

It is also not a condition to ignore because they are often in a lot of pain and have difficulty walking around.

You should take them to the vet as soon as possible because the disease can spread to their legs and cause paralysis.


Then there is Myokymia which is a condition where the dog experiences spasms involuntarily. This condition affects isolated muscles, one at a time.

It could be a problem in the eyes, neck or a leg in Jack Russells. Usually, this condition is caused by anxiety, dehydration, too much exercise, fatigue and lack of sleep.

It’s not difficult for you to diagnose this condition but it might not be a bad idea to check in with the vet.

Addison’s Disease

Addison’s disease is also considered a rare one but they do affect female dogs more than their male counterparts.

It is the result of a deficiency of aldosterone and cortisol and shaking is only one of the symptoms.

Other symptoms like increased peeing, thirst, losing weight randomly, vomiting and diarrhea are more telling of the problem at hand.

Check with your vet and see what can be done as soon as you can.

Old Age

Like all dogs, Jack Russells also run into some problems as they age. Sometimes, shaking is a result of how frail they have grown in their old age.

They don’t have as much energy as they did in their youth and that’s just a fact with all dogs.

Their bones and muscles get weaker and it might cause pain which leads to a lot of shaking.

But the shaking could be the result of the pain they are in due to medical conditions that also develop with age but it is hard to tell.

Other possible reasons why a Jack Russell might be shaking is because of medical conditions like:

  • Congenital myasthenia gravis
  • Epileptic seizures
  • Hydrocephalus
  • Myelodysplasia
  • Scotty cramp

Parting Thoughts

Now you know that there are a lot of reasons why Jack Russells shake.

Usually, it is to spend any extra energy they have. Sometimes it’s fear or anxiety and other times it is excitement.

But they might also be trying to get rid of the hairs they have shed that are still stuck on their skin. These are reasons you don’t have to worry much about.

But there are also medical conditions that cause them to shake and those need the attention of the vet.