BSAVA 2014 is off to a tremendous start and we are hugely proud to have nurses, residents and senior surgeons involved across a variety of streams. However there is one shining star this year: Anna Tauro (Neurology Resident) will be receiving a prestigious BSAVA Award for the Clinical Research Abstract she presented last year. Anna was up against over 100 vets and won the award with her research work on Vizla Polymyositis. Anna will receive her award on Saturday, 5th April at 1530 in Hall 3 (Foyer Balcony) – if you are at BSAVA please come along to show your support!
For folks who would like a little more information on Anna’s work please read on – complex in places but worth the read!
The clinical research abstract was based on a retrospective cohort study of an emerging and diagnostically challenging disorder affecting Hungarian Vizsla dogs, characterised by a generalised inflammatory myopathy. Over 334 medical records were reviewed (1999-2013) and 70 Hungarian Vizslas were found to be affected. The project was coordinated by Dr. Clare Rusbridge (Chief of Neurology at Fitzpatrick Referrals), and based on the clinical records researched and collected with great dedication by Di Addicott. The other vital collaborators were Penny Knowler, Rob Foale, Jonathan Massey, Lorna Kennedy, Alison Haley, Michael Day, Caroline Hahn, Chloe Bowman, and Sam Long.
In Anna’s study the mean age of onset was 2.3 years (range 0.2–8.8 years old); male dogs were slightly overrepresented. The most consistent clinical signs were dysphagia and regurgitation due to tongue, pharyngeal and oesophageal dysfunction; and masticatory muscle atrophy.
Although a marked elevation in muscle enzymes was an indicator of disease, Vizsla Polymyositis could not be ruled out if muscle enzymes were normal or only minimally elevated. Given the clinical presentation of Vizsla Polymyositis, the most important differentials were masticatory muscle myositis (MMM) and myasthenia gravis (MG), thus, serum titres for antibodies against type 2M fibres and the acetylcholine receptor should be evaluated.
Thoracic radiographs and contrast study may reveal megaoesophagus; however, if less severe or dynamic disease of the oesophagus is present, fluoroscopy may be useful, especially in the detection of swallowing disorders that mainly involve the oral and pharyngeal phase. It is advisable to perform these studies with great care in order to avoid barium aspiration pneumonia.
It would be of great benefit if there was an easy and more reliable method of detecting oesophageal dysmotility in dogs. In man, oesophageal manometry is considered the ‘gold standard’ for assessing oesophageal motor function. High-resolution manometry could be useful in the detection of oesophageal disorders in animals, and Fitzpatrick Referrals is involved into a research project to determine its valuable use in these cases.
Electromyography (EMG) of the appendicular and axial muscles including the masticatory muscles showed generalised abnormal spontaneous activity, including positive sharp waves, fibrillation potentials, prolonged insertional activity, and occasional pseudomyotonia.
In order to confirm a muscle disease, a biopsy is required. Muscle biopsies were taken from the most accessible sites such as masseter, temporalis, lingual, triceps, and cranial tibial muscles. However in our study EMG and MRI were valuable tools to identify appropriate muscle to sample. Lingual muscle biopsy is especially indicated when dogs are presented with oropharyngeal dysphagia. When obtaining biopsy samples end-stage muscles should be avoided, as they have a very little diagnostic value.
Multifocal lymphoplasmacytic and macrophagic cellular infiltrations having an endomysial and perimysial distribution with invasion of non-necrotic fibres was the most common histopathological finding. Degenerative (e.g. variation in myofibre size, myofibre hyalinisation, necrosis, angular atrophy, nuclear internalisation, granular sarcoplasm, sarcolemmal fragmentation) and regenerative changes (e.g. cytoplasmic basophilia, nuclear rowing, presence of type 2C fibres, compensatory hypertrophy) were variably found.
Vizsla Polymyositis is assumed to be an autoimmune disease because of the response to immunosuppressive treatment. The cornerstone of the treatment is glucocorticoid therapy due to its cost and clinical effectiveness. Particular care must be taken if there is a risk of aspiration pneumonia. A combination of immunosuppressive agents was preferable to reduce long-term corticosteroid side effects and /or when the clinical response to monotherapy was poor. In our study the most common polytherapy was prednisolone and azathioprine.
In order to reduce the risk of aspiration pneumonia and to aid swallowing dogs should be fed from a height and with small meals 4-6 times daily. In some cases an anti-gulping bowl (Dogit® Go Slow Anti-Gulping Dog Bowl, Rolf C. Hagen Ltd., West Yorkshire, UK) was useful especially in dogs with polyphagia due to high dosage of corticosteroids.
Supportive treatments including gastroprotectants and prokinetics were also commonly prescribed. The prognosis remains guarded, as treatment can only manage the disease. Recurrence of clinical signs, aspiration pneumonia, and perceived poor quality of life are the most common reasons for humane euthanasia. Early diagnosis, careful monitoring and slow withdrawal of drugs improves prognosis.
