We present a case of Alexander's disease (AD) in a Bernese mountain dog. The male dog had a clinical history of tremors of the hind legs and posterior weakness, which deteriorated rapidly to posterior paresis and tetraparesis. After a disease duration of 4 weeks the dog was euthanatized at 13 weeks of age. Macroscopically the brain showed moderate enlargement of the lateral ventricles. Histologically there was marked proliferation of astrocytes with abnormally large cell bodies in the white matter of the brain and the white and gray matter of the spinal cord. In these regions numerous round, club-shaped, or elongated deposits consistent with Rosenthal fibers (RFs) were found. They were most prominent in perivascular, subependymal, and subpial areas where they were perpendicularly arranged. Additionally there was considerable loss of myelin. Immunohistologically the RFs were positive for glial fibrillary acidic protein and alpha B-crystallin. Under the electron microscope the RFs were found to be located in the cell bodies and processes of astrocytes and appeared as osmiophilic irregularly formed bodies of uneven size with distinct borders that were tightly associated with glial filaments. The histological, immunohistochemical, and ultrastructural findings of this canine case of AD are identical with those in human cases.

Brainstem auditory-evoked potentials (BAEPs) were recorded from 26 dogs with intracranial neoplasia. The tumors were grouped according to their neuroanatomic location. Normal BAEPs were recorded from 12 dogs with cerebral (6/7), diencephalic (4/4), cerebellar (1/1), and multifocal tumors (1/5). Abnormal BAEPs were recorded from 14 dogs were cerebral (1/7), cerebellar/brainstem (4/4), brainstem (5/5), and multifocal tumors (4/5). Analysis of the multifocal neoplasms showed that alterations of BAEPs correlated with the degree of brainstem involvement. Overall, 13 of the 14 dogs with abnormal BAEPs had tumors involving the brainstem. The changes of the BAEP correlated with the extrinsic or intrinsic location of the tumor relative to the brainstem. The BAEP reflected the right, left, or median location of the tumor in 7 of the 14 abnormal recordings. In 1 dog, the BAEP was abnormal contralateral to the tumor side. A peripheral hearing disorder was excluded in most dogs based on the presence of peak I.

Summary In four new‐born Braunvieh calves suffering from connate recumbency and body tremor, a hitherto not described myelination disorder of the spinal cord was examined. Bilateral symmetric hypo‐ as well as demyelination in several spinal tracts were the most conspicuous findings, affecting the ascending gracile funiculus, the ascending dorsolateral spinocerebellar tract, and the mainly descending sulcomarginal tract. Deficient myelin production, loss of myelin, consecutive axonal degenerations, and prominent astrogliosis within these tracts were the histological hallmarks of the disease. This possibly inherited primary myelination disorder of the spinal cord differs markedly from known hereditary neurological diseases in Brown Swiss and Braunvieh cattle, respectively, i. e. the weaver‐syndrome and the spinal muscular atrophy.

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