Magnetic resonance imaging findings in acute canine distemper virus infection

Abstract

Demyelination is the prominent histopathological hallmark in the acute stage of canine distemper virus infection. Magnetic resonance imaging is an important diagnostic tool in human beings to determine demyelination in the brain, for example in multiple sclerosis. Five young dogs with clinically suspected canine distemper virus infection were subjected to magnetic resonance imaging of the brain and histopathological and immunohistochemical examinations. Hyperintense lesions and loss of contrast between grey and white matter were detected in T2-weighted images in the cerebellum and/or in the brainstem of three dogs, which correlated with demyelination demonstrated in histopathological examination. Furthermore, increased signal intensities in T2-weighted images were seen in the temporal lobe of four dogs with no evidence of demyelination. Magnetic resonance imaging seems to be a sensitive tool for the visualisation of in vivo myelination defects in dogs with acute canine distemper virus infection. Postictal oedema and accumulation of antigen positive cells have to be considered an important differential diagnosis.

Imaging Diagnosis—chronic Canine Distemper Meningoencephalitis

“…MR imaging findings in meningoencephalitis include hyperintensity on T2WI, hypointensity on T1WI, contrast enhancement of brain parenchyma and meninges, loss of cortical gray/white matter demarcation, mass effect, and space‐occupying lesions. Lesions can be focal, multifocal, or diffuse and involve gray and white matter of all divisions of the brain 5–10 . Changes on MR imaging reflect the anatomic distribution of inflammation, edema, demyelination, gliosis, increased vascular permeability, and hemorrhage 11–13 …”

“…Four of five dogs with acute distemper encephalitis that underwent MR imaging had large, multifocal, asymmetric, ovoid‐shaped, T2‐hyperintense lesions in the gray matter of the forebrain, primarily affecting the temporal lobe 5 . These lesions were isointense or hypointense on T1WI with inconsistent contrast enhancement.…”

“…Lesions can be focal, multifocal, or diffuse and involve gray and white matter of all divisions of the brain. [5][6][7][8][9][10] Changes on MR imaging reflect the anatomic distribution of inflammation, edema, demyelination, gliosis, increased vascular permeability, and hemorrhage. [11][12][13] Four of five dogs with acute distemper encephalitis that underwent MR imaging had large, multifocal, asymmetric, ovoid-shaped, T2-hyperintense lesions in the gray matter of the forebrain, primarily affecting the temporal lobe.…”

Magnetic Resonance Imaging for the Differentiation of Neoplastic, Inflammatory, and Cerebrovascular Brain Disease in Dogs

“…Reviewers were then asked to specify the most likely brain disease represented by the MR abnormalities. Reviewers were permitted to diagnose inflammatory lesions as granulomatous meningoencephalitis (GME), necrotizing encephalitis (NE), bacterial encephalitis, canine distemper virus encephalitis, Neospora caninum , fungal encephalitis, or other/unknown. Neoplastic lesions could be classified by reviewers as meningioma, glioma (oligodendroglial, astrocytic, or mixed‐glial origin), choroid plexus tumor (papilloma or carcinoma), ependymoma, histiocytic sarcoma, lymphoma, hemangiosarcoma, pituitary tumor, metastatic neoplasia, or other/unknown.…”

Infectious and non‐infectious inflammatory causes of seizures in dogs and cats

“…It is uncertain if this relates to infection or is the result of postictal oedema following recent seizure activity. Hyperintense lesions and a loss of contrast between the grey and white matter on T2-weighted images are also observed and confined to the cerebellum and/or brainstem (Bathen-Noethen and others 2008). In contrast, the images obtained by MRI of dogs with chronic distemper encephalitis may be normal or show focal or multifocal lesions with a predilection for the white matter consistent with demyelination.…”