woman sitting on the ground massaging dog's back

Difference between Spasm, Twitching and Fasciculation

Even though the three can all seem similar on the surface, they are in fact very different. All three can potentially be quite concerning and should be assessed by a veterinarian.


Sudden, involuntary contraction of a large group of muscles. It is usually painful, both in the area of the spasm and in areas of referred pain. It can cause the whole muscle, limb or area of the body to move. Can cause the dog to vocalize, jump up as if startled or bite, lick or scratch at the affected area. Below is a video demonstrating how to safely help your dog when they are experiencing a spasm. Note: the dog in the video is not experiencing a spasm, this was for demonstration only.


Involuntary contraction of opposing muscle groups. Even though usually not painful, it can last for a prolonged period of time and be debilitating to the dog’s quality of life. Often related to neurological disorders and requires veterinary intervention.


Involuntary, brief twitch of muscle visible under the skin. Occurs irregularly and doesnt move the affected muscle. Causes can range from


  • muscle exertion/fatigue
  • stress
  • dehydration
  • lack of sleep

To more serious:

  • muscle weakness/atrophy
  • motor nerve damage
  • myopathy
  • muscular dystrophy

The video below shows an example of muscle fasciculation in a dog’s shoulder.

These are just some possible causes, there are many more. But if you notice muscle twitching in your dog, it’s best to consult with your vet to make sure it’s benign and not an early sign of trouble.