The first report of episodic muscle hypertonicity in Norwich terrier (NT) dogs was first reported in 1984. Since then, our knowledge has advanced little. Paroxysmal dyskinesias (PxDs) can be inherited or acquired and can be primary or secondary to other disorders. In dogs, primary PxDs reports have been increasing in various breeds and are characterized by episodic hyperkinesia that impairs posture and locomotion without a loss of consciousness.
This investigation aimed to understand the condition better in NTs, taking into account aspects including clinical course, family history and prevalence in the United Kingdom. 198 questionnaires were analyzed and, following a review of the veterinary records, interpreting available videos and phoning owners, 26 NT dogs were considered to have paroxysmal dyskinesia.
In all 26 cases, the NT dogs were neurologically normal between episodes and no significant deviations were detected in their serum biochemistry or hematology values. Apart from reporting that the levels of consciousness and awareness remained normal during the observed occurrences, almost half of the owners suggested that their dog seemed to be able to predict the episode as they would seek them out before it occurred.
All the episodes were self-limiting and none exceeded 30 minutes. In the majority, the dogs were not able to stand up. The most common triggers were excitement and stress. In some cases, diet changes were successful in alleviating the condition.
The study concluded that Paroxysmal Dyskinesia in Norwich Terriers seems similar to paroxysmal non-kinesigenic dyskinesia in humans, particularly in terms of the most commonly reported triggering factors. Investigating the genetic components involved in this condition is important to restrict the spread of the disorder. This study is also an important tool to better classify both affected and unaffected dogs.
Del Risio L. et al. Paroxysmal Dyskinesia in Norwich Terrier Dogs. Wiley InterScience, May 2016. DOI: 10.1002/mdc3.12334