I got chatting to a lovely lady recently whose dog suffers from paroxysmal dyskinesia. She was telling me that it is not that uncommon and yet hardly anyone seems to have heard of it.
So, let's talk about Canine Episodic Movement Disorders and you never know, it may help someone.
Episodic movement disorders may be a form of motor seizure. Terms used include atypical epilepsy, atypical seizures, muscular hypertonicity, hyperkinesis, paroxysmal dyskinesia or episodic dyskinesia.
Throughout this article I may refer to episodic movement disorders (paroxysmal movement disorders) by any or all of the above terms. Mostly I will use the group heading of Paroxysmal Dyskinesia (PD).
Please note that there are also some more breed specific terms that you may come across - Episodic Falling , Scottie Cramp, Epileptoid Cramping Syndrome or Spike's disease.
Episodic Movement Disorders
Paroxysmal dyskinesias are episodic movement disorders in which abnormal, involuntary movements are present only during attacks. Paroxysmal means symptoms are noticeable only at certain times with the 'patient' seeming perfectly normal the rest of the time. Dyskinesia means involuntary body movements.
Some dogs will only have one or two episodes in their lifetime while other dogs may have more frequent or longer lasting episodes.
A gorgeous Black Labrador Retriever called Monty can be seen in the video below having an episode of paroxysmal dyskinesia:
Epileptic Seizures vs Atypical Seizures
With classic epileptic seizures you would typically see the dog lose consciousness and move or jerk frantically during the fit, seemingly unaware of anything else going on around them. In Canine Paroxysmal Dyskinesia however the dog appears to be conscious during an episode and can even make some voluntary movements or appear to be aware of their surroundings and be responsive to others. There is also no loss of bladder or bowel control or excessive salivation.
During a paroxysmal dyskinesia episode the dog may lay or fall down or sometimes can remain standing but in a frozen position. Unlike epileptic seizures, the dog having a PD episode won't tend to show frantic fit-type movements but may curl one or more limbs towards their body (a cramping or spasm of the hind limbs is common) or show slight movements, trembling or licking motions. The spasms thwart any attempts at voluntary movement so while the dog may attempt to walk, they are unable to do so during an episode.
The video below is courtesy of the Canine Epilepsy Network from their article Chinook "Seizures" by Dennis O'Brien, DVM, PhD.
Which breeds are affected?
Davies Veterinary Specialists, in their Paroxysmal Dyskinesia article discuss paroxysmal movement disorders in certain breeds of dog:
"In veterinary medicine, PD have been described in a number of breeds - Cavalier King Charles spaniel, Border terrier, Cairn terrier, Scottish terrier, Dalmatian and Norwich terrier, Boxer, Bichon Frise, Pugs, Chinook, in which they have been ‘labelled’ as breed-specific entities. Although not reported in the literature, similar paroxysmal movement disorders are increasingly seen in other breeds, particularly Jack Russell terriers or Labrador retrievers in the UK."
In the photos on the right you can see muscle contractions and stiffness starting in the hind legs and progressing to the font legs. Arching of the lumbar spine can also be seen. The dog remained conscious and responsive to her owner.
Causes and diagnosis
While some owners have reported that specific foods or events appear to trigger an episode, the general concensus is that PD episodes occur without warning but may be more common when the dog is falling asleep or waking up. Excitement and exercise are also possible triggers. However, the underlying cause is unknown, with the majority of episodes being described as idiopathic (i.e. of unknown cause).
Getting a diagnosis can be tricky as these disorders remain a grey area. While episodic movement disorders are being increasingly recognised by the medical profession, they are still commonly mistaken for epileptic seizures by owners and vets. There is significant variability and overlap in the clinical presentation for paroxysmal movement disorders and epileptic seizures, especially simple partial epileptic seizures where the patient is still conscious.
Also, as they are episodic, it can be difficult to show your vet exactly what is happening. When examined between attacks, neurological evaluation is often completely normal. Home video has helped somewhat in this respect.
This lady has filmed her dog Leo to show what happens during one of his atypical "seizures":
I am sure you won't be surprised to learn that paroxysmal dyskinesia can be extremely frustrating to diagnose and treat apart from a few specific cases. Episodic Falling Syndrome in Cavalier King Charles Spaniels may respond to acetazolamide. A study in 2015 concluded that Canine Epileptoid Cramping Syndrome in Border terriers could be a gluten-sensitive movement disorder that may respond to a gluten free diet, although owners appear to have had varying levels of success with dietary changes. Keppra (Levetiracetam) has reportedly helped some affected Labradors but this is purely anecdotal. The use of Selective Serotonin Reuptake Inhibitor drugs (SSRIs) also looks promising. However, most cases of PD do not respond to anti-epileptic medications or other treatments.
Davies Veterinary Specialists conclude that:
"Based on these results and our experience trying various medication for PD, we usually only advise treatment if the frequency of these episodes of PD is reaching one or more than one episode a week."