An inherited episodic head tremor syndrome in Doberman pinscher dogs.

Episodic head tremor anecdotally occurs in the Doberman pinscher dog breed, but it is not described in sufficient detail in the literature. We evaluated 87 Doberman pinschers affected with episodic head tremor and appropriate controls. The data analyzed were collected through detailed questionnaires, elaborate telephone interviews, and video recordings. Affected dogs underwent clinical, neurological, and laboratory examination, and a detailed diagnostic workup was conducted in 5 affected dogs. Pedigrees of affected dogs were collected and reviewed. The affected dogs expressed individual phenotypes of either horizontal or vertical head movements, but rarely did a dog exhibit head movements in both directions. There was considerable variation in duration (10 seconds to 3 hours; median: 3 minutes), frequency of occurrence (1-20 episodes/day; median: 2/day) of head tremor and length of the period without head tremor (1-1,800 days; median: 60 days). Subtle dystonic posturing of the head and neck during head tremor was evident on video recordings of 5 dogs. Certain exceptional conditions such as illness, surgery, some medications, heat, pseudopregnancy, or pregnancy triggered episodes. Two main important forms of episodic head tremor were identified: a familial early-onset form (age < 1 year) that affected littermates and a sporadic form. Affected dogs were traced back to 1 common sire, also including sporadic cases. Episodic head tremor is an inherited, paroxysmal movement disorder that affects the Doberman pinscher breed. Identification of the causative genes in the future will allow us to obtain a more detailed description of the syndrome.