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Spinocerebellar Ataxia with Myokymia: Facts

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Ataxia: JRTs can be affected with Cerebellar Ataxia OR Spinocerebellar Ataxia. Not both. It is not the norm for an entire litter of 4 to be affected with ataxia. Usually its one or two… but, as with all diseases… one never knows for sure.

Cerebellar Ataxia (early onset): Age at onset 2 weeks (or as soon as their eyes open). Pups, when learning to walk are wobbly legged, but the normal pups get stronger and the ataxic pups get worse.

Spinocerebellar Ataxia: Age at onset 2 mos. to 8 mos. At this time, there are no known cases of JRTs with Spinocerebellar Ataxia without Myokymia.

Neurologic abnormalities:

  • An uncoordinated gait initially worse in the rear limbs that can include goose stepping;
  • The gait is spastic and eventually the front legs are affected;
  • You might notice the pup is standing in a tripod stance. Hind legs close together and front legs apart giving the impression the pup is weak and unbalanced looking;
  • Head bobbing is also characteristic of ataxia;
  • One owner reported that she noticed her pup would NOT go down the stairs but it would come up. Normal pups will eventually learn to go up and down stairs; ataxia pups may not. It is just an observation.
  • As the disease progresses they begin to fall, however, the falling becomes more frequent between one and two years of age.

A Spinocerebellar Ataxia pup is not easily recognized… in fact, many think they have a “clumpy” puppy. Breeders observe their pups on a daily basis and might eventually see that its movement is not normal, but it’s hard to get an “outsider” to see it. I struggled with this fact for several months in 2005. I knew something was wrong, no one else could see it and even my vet seemed surprised when I mentioned Ataxia.

Many times this disease has been misdiagnosed thus the dog ultimately gets euthanized and never gets into the research program.

Myokymia: Usually appears between the ages of 2 mos. To 30 months. It is an involuntary muscle disorder whereupon the muscles become hyperactive and creates heat, causing hyperthermia and in turn can cause a seizure.

Myokymia is associated with Spinocerebellar Ataxia. It can be a “stand alone” disease in other breeds, however, the combination of Spinocerebellar Ataxia and Myokymia appears to be in JRTs only. Pups with Cerebellar Ataxia are usually euthanized before Myokymia gets a chance to develop. So, it is not known if Myokymia can appear with Cerebellar Ataxia (Early Onset).

Symptoms of Myokymia

In my experience and others, we have noted that the pup or adult when having an episode;

  • goes into a recumbent position;
  • hind limbs & fore limbs are stiffened (severity of stiffness is variable);
  • paws may be curled;
  • vigorous facial rubbing sometimes occurs;
  • muscle activity in the shoulder/hindquarters give the appearance of worms being under the skin (an unmistakable symptom of Myokymia);
  • core body temp is extremely high… 107+; the dog goes into hypothermia.
  • Eyes appear to be relatively normal, they can drink if offered water and lift their head.

I learned, and it is supported with research documentation, that during this time of extreme overheating, you can immerse the dog in lukewarm/cool water via shower, tub, etc. Obviously, these episodes may occur when you and your dog are away from home. I learned to have a spray water bottle available for those emergency situations. Cooling off the dog is key to the seizure subsiding. Very cold water or ice could be more of a shock to the dogs system; lukewarm or unchilled water is better. I learned, very quickly, that the more seizures the dog had… the more they had, and the seizures will shorten its life. It became my goal to attempt to avoid them.

It has been noted that excitement in a JRT with Ataxia/Myokymia creates the perfect environment for a seizure. It was very difficult to keep my dogs low key. They were 100% JRT and never knew they were handicapped nor did they appear to be in pain. When my A/M (Ataxia/Myokymia) dogs had a seizure, I noted that those who were with him looked at him with curiosity, sniffed him, and left him alone. My lab, on the other hand, would lick either of the dogs until the seizure subsided. Did he know that they needed cooling? I don’t know. But the Lab kept watch over them.

In both of my dogs and others noted, it was the seizures that ended their lives… not the Ataxia. One died in my presence and the other I euthanized after a day of seizures… back to back to back.

One Ataxia/Myokymia dog was placed on phenobarbital as a way to control the seizures. It had no effect. Only your veterinarian can tell you if any prescribed medications might be of help.


Ataxia is a progressive disease. It will not get better but worsen over a period of time. Ataxia dogs can live several years but their quality of life is debatable. It is up to the owner AND their veterinarian to make life or death decisions.

A definitive diagnosis for Ataxia (via necropsy) can be performed on pups that are a minimum of 5 weeks of age or older.

Ataxia can be inherited or produced by other medical issues that are ataxic in appearance. A necropsy will tell if your dog has the inherited type (Cerebellar – early onset or Spinocerebellar -late onset).

Ataxia w/Myokymia are progressive diseases when coupled together are fatal. In my limited experience, plus knowing other owners who have experienced it… it has a 100% mortality rate. This is not research data, just my, and others, observations. The life span of a dog with A/M is predicted to be approx. 30 months. However, research may prove it to be different and as you know, research is always ongoing. My dogs lived until 21 and 23 months respectively.

At this time, it is NOT recommended to do elective surgery or an MRI where anesthesia is administered. An elective surgery might be as simple as spaying or neutering. I have been told by my veterinarian and have read in research papers that anesthesia can cause the ataxia to worsen at a more rapid rate. And, as I’ve stated before research is ongoing and thoughts re anesthesia could change in this area.

A veterinarian could recommend a medical procedure that may include anesthesia. This is a decision between the veterinarian and the owner. The veterinarian knows best.

Cheryl Costello