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A breed-specific polymyositis (generalized inflammatory myopathy) has been recognized in Hungarian Vizsla dog (Foale et al, BSAVA 2008 and Haley et al,ACVIM 2009).  The most common presenting signs are eating, drinking and swallowing difficulty (pharyngeal dysphagia) with loss of the muscles on the head (masticatory muscle atrophy).
We are looking for DNA from

• Any breed with a histopathological diagnosis of polymyositis
• Vizsla with at least one of the following in addition to dysphagia (eating, drinking and swallowing difficulty with or without excessive salivation)
o Creatine kinase > 1000U/L
o Exercise intolerance
o Megaoesophagus identified on thoracic radiographs
o Oesophageal motility problem detected by fluoroscopy
o MRI changes consistent with polymyositis
o Electrophysiological changes consistent with muscle disease
• Vizslas with siblings diagnosed with polymyositis
• Vizslas with offspring diagnosed with polymyositis.

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Other common signs include regurgitation, drooling saliva and difficulty and/or pain on opening the jaw.
The creatine kinase is elevated to values greater than 1000 U/L - at least in the early stages of the disease. Thoracic radiographs may reveal a megaoesophagus (dilated, usually air filled, oesophagus).

Fluoroscopy may detect oesophageal motility disorders.  Electromyography can be normal or may reveal spontaneous activity suggestive of polymyositis (prolonged insertional activity and spontaneous activity including pseudomyotonia).
The tongue and pharynx are the most useful muscles for electrophysiological evaluation. MRI may reveal hyperintensity within muscle groups. Histopathologic examination of muscle biopsy may reveal multifocal areas of lymphohistiocytic and plasmacytic myositis with fibrosis however active inflammation may not be appreciated if end stage muscle or limited areas are biopsied. For more information see