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The basic diagnostic work-up of a suspected stroke REFERENCES
includes a clinical and neurological examination, haematology and serum biochemistry, and haemostatic parameters, such as APTT, PT and thromboelastography (TEG),  brinogen and D-dimer, if possible.
Eventually, the diagnosis of a stroke, ischaemic or haemorrhagic, is based on magnetic resonance imaging (MRI) of the brain.
With ischaemic stroke, signal changes on MRI are mainly due to the cellular changes caused by ischaemia and
a growing brain oedema. Conventional MRI typically reveals a well-demarcated lesion, which con nes to a known arterial territory. There is usually no or only little mass effect, and the lesion is characterised by a hypo- or isointense signal on T1-weighted images (WI), and
a hyperintense signal on T2-WI and  uid-attenuated inversion recovery (FLAIR). There is usually only very little contrast enhancement with ischaemic stroke2,7.
With haemorrhagic stroke, the signal changes on MRI are primarily related to the oxygen saturation of haemoglobin causing a shift in the paramagnetic signal of the iron ions as haemoglobin is degraded through several forms (oxy-, deoxy-, and methaemoglobin) over time. Accordingly,
an acute haemorrhage (<24h) typically appears hypo- to isointense on T1-WI, and hyperintense on T2-WI, but hypointense in both T1-WI and T2-WI at 24-72h. From 3-7 days, a haemorrhage is usually hyperintense in T1- WI and hypointense in T2-WI. As opposed to ischaemic stroke, the lesion is typically less well demarcated, and some mass effect may be visual6.
Treatment & prognosis
At present, there is no speci c treatment for stroke in dogs. Supportive care, aiming at preventing secondary brain damage, and optimising rehabilitation should be conducted. If any underlying diseases are identi ed, these should obviously be addressed8.
Fortunately, most dogs with ischaemic stroke seem to have a good prognosis, especially if they survive the  rst 30 days9. Survival is, however, dependent on the site of infarction, and the prognosis is therefore guarded in dogs with severe brainstem and mid-brain signs8.
In dogs surviving the acute state of ischaemic stroke, marked improvement is usually seen within the  rst 30 days, and complete or nearly complete motor function is regained within 1-3 months. The possibility of recurrent episodes is, however, described8.
For haemorrhagic stroke the identi cation and
treatment of a possible underlying cause of haemostatic dysfunction is crucial. Such conditions may result in multiple concurrent lesions, which may explain why haemorrhagic stroke is apparently associated with a less favourable outcome than ischaemic stroke6.
1. World Health Organization. WHO STEPS Stroke Manual: The WHO STEPwise approach to stroke surveillance. 2006
2. McConnell JF, Garosi L, Platt SR, et al. Magnetic resonance imaging  ndings of presumed cerebellar cerebrovascular accidents in twelve dogs. Veterinary Radiology & Ultrasound 2005;46:1-10
3. Thomsen B, Garosi L, Skerritt G, Rusbridge C, Sparrow T, Berendt M, Gredal H. Neurological signs in 23 dogs with suspected rostral cerebellar ischaemic stroke. Acta Veterinaria Scandinavica 2016;58:40. DOI 10.1186/s13028-016- 0219-2
4. Gredal H, Skerritt GC, Gideon P, Arlien-Soeborg P, Berendt M. Spontaneous ischaemic stroke in dogs: clinical topographic similarities to humans. Acta Neurologica Scandinavica 2013 DOI: 10.1111/ane.12092
5. Gonçalves R, Carrera I, Garosi L, et al. Clinical and topographic magnetic resonance imaging characteristics of suspected thalamic infarcts in 16 dogs. The Veterinary Journal 2011;188:39-43
6. Lowrie M, De Risio L, Dennis R, Llabres-Diaz F, Garosi L. Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial haemorrhage. Veterinary Radiology & Ultrasound 2012;53:381-388
7. Wessmann A, Chandler K, Garosi L. Ischaemic and haemorrhagic stroke in the dog. The Veterinary Journal 2009;180:290-303
8. Garosi L, JF, Platt SR, Barone G, Baron JC, de Lahunta A, Schatzberg SJ. Results of diagnostic investigations and long-term outcome of 33 dogs with brain infarction (2000-2004). Journal of Veterinary Internal Medicine 2005;19:725-31
9. Gredal H, Toft N, Westrup U, Motta L, Gideon P, Arlien-Søborg P, Skerritt, Berendt M. Survival and clinical outcome of dogs with ischaemic stroke. The Veterinary Journal 2013;196:408-13
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