Paroxysmal Dyskinesia in Norwich Terrier Dogs

Abstract

View Supplementary Video 1 View Supplementary Video 2 Background Episodic muscular hypertonicity in Norwich terrier dogs was first reported in a brief communication in 1984. Since then, the condition has remained poorly characterized. Objectives The aims of this study were to characterize the phenomenology, clinical course, and family history of paroxysmal dyskinesia in the Norwich terrier and to estimate its prevalence in the United Kingdom. Methods The owners of Norwich terrier dogs born since January 1, 2000 were invited to complete a specifically designed questionnaire aimed at identifying affected and unaffected dogs and investigating the clinical characteristics of this paroxysmal dyskinesia. Pedigrees were collected and reviewed. Results The questionnaire was returned for 198 Norwich terrier dogs. Of these, 26 (13%) were classified as affected by paroxysmal dyskinesia after revision of the questionnaires and after obtaining videos of the episodes, veterinary medical records, and telephone interviews with the owners. All dogs were neurologically normal between episodes. No significant abnormalities were detected on diagnostic investigations. Mean age at the first episode was 3 years. The episodes were characterized by sustained muscular hypertonicity in the pelvic limbs, lumbar region, and thoracic limbs, impairing posture and locomotion without loss of consciousness. Episode frequency varied both between and within individuals. Stress, anxiety, excitement, and variation in daily routine were recognized as episode triggers in 13 dogs. Episode duration generally was from 2 to 5 minutes (range, from < 2 to 30 minutes). The majority of affected dogs were related. Conclusions Paroxysmal dyskinesia segregates in an extended pedigree of Norwich terrier dogs and thus is potentially an inherited disorder in this breed.

Phenotypic characterization of paroxysmal dyskinesia in Maltese dogs

“…1 Although PDs remain poorly characterized in the veterinary literature, they have become an increasingly recognized condition over the last decade, especially because of the fact that smartphone technology has enabled dog owners to record episodes at home and show them to their veterinarians. [2][3][4][5][6][7][8][9][10] In human medicine, PDs can be classified clinically in 3 major categories, including paroxysmal kinesigenic dyskinesia (usually brief [<2 minutes] episodes typically precipitated by sudden movements, which can be exacerbated by stress, menses, cold, and heat), paroxysmal nonkinesigenic dyskinesia (PNKD; episodes of involuntary movements that occur spontaneously, lasting minutes to hours) and paroxysmal exertion-induced dyskinesia (episodes induced by prolonged sustained exercise, lasting between seconds to 30 minutes). 11 Most PDs described in dogs resemble PNKD in humans but, a recent study proposed a clinical classification in veterinary medicine, including genetic, secondary (eg, drug-induced PD and structural intracranial disease), dietary, and unidentified (presumed genetic) causes.…”

Paroxysmal non‐kinesigenic dyskinesia characterised by dystonia in a crossbred dog

“…Paroxysmal dyskinesias in veterinary patients have been described in several canine breeds. Among others, these breeds are documented with particular disorders 3 5–8 14 21–23 Border terrier, CECS (sometimes called ‘Spike’s disease’)—PNKD, recently renamed PGSD Norwich terrier—PNKD, unidentified cause Cavalier King Charles spaniel, episodic falling syndrome—PNKD, genetic background Chinook dog, ‘Chinook seizures’—PNKD, unidentified cause German shorthaired pointer—one report of a PKD responsive to phenobarbital Scottish terrier, ‘Scottie cramp’—PNKD, unidentified cause …”

“…Treatment options for dyskinesias are not well documented, though several drugs have been tried with varying results 2 3 6 7 10 15 23. Diazepam may be of some benefit in stopping severe episodes, though not consistently 6 23. In most cases, administration of antiepileptic drugs such as phenobarbital is not very effective.…”

“…The questions in online supplementary file S3 were composed by the first author according to criteria and data from several publications on canine paroxysmal movement disorders. [2][3][4][5][6][7] The questionnaires revealed several key points of information. The following points were of specific interest and strongly suggested a paroxysmal movement disorder was more likely than an epileptic seizure 3 7 8 : ► No vigorous shaking of body parts is noticed.…”

“…These documents with translations of the owner’s answers can be found in the online supplementary file S1‐S3. The questions in online supplementary file S3 were composed by the first author according to criteria and data from several publications on canine paroxysmal movement disorders 2–7…”