A primary demyelinating disorder of young cattle

Pontine infarction in a dog with unilateral involvement of the trigeminal motor nucleus and pyramidal tract

An unusual case of unilateral trigeminal neuronopathy in a dog is reported, in which the motor nucleus of the trigeminal nerve and the ipsilateral corticospinal tract were destroyed, apparently by a cerebrovascular accident (stroke). Hemiplegia did not occur. Neuropathological changes are described, including remyelination by Schwann cells in the central nervous system. The case illustrates the importance of central nervous system post-mortem examination when establishing causes of cranial nerve paralysis.

Congenital defects of the ruminant nervous system

Abnormalities of the nervous system are common occurrences among congenital defects and have been reported in most ruminant species. From a clinical standpoint, the signs of such defects create difficulty in arriving at an antemortem etiology through historical and physical examination alone. By first localizing clinical signs to their point of origin in the nervous system, however, a narrower differential list can be generated so that the clinician can pursue a definitive diagnosis. This article categorizes defects of the ruminant nervous system by location of salient clinical signs into dysfunction of one of more of the following regions: cerebrum, cerebellum,and spinal cord. A brief review of some of the more recognized etiologies of these defects is also provided. It is important to make every attempt to determine the cause of nervous system defects because of the impact that an inherited condition would have on a breeding program and for prevention of defects caused by infectious or toxic teratogen exposure.

A familial peripheral neuropathy and glomerulopathy in Gelbvieh calves

Nine Gelbvieh calves originating in four herds and clinically presenting with rear limb ataxia/paresis had histopathologically confirmed peripheral neuropathy and a proliferative glomerulopathy. Degenerative lesions were severe in peripheral nerves, dorsal and ventral spinal nerve roots, and less marked in dorsal fasciculi of the spinal cord. Cell bodies of spinal ganglia were minimally diseased; ventral horn neurons occasionally had central chromatolysis and nuclear displacement. Glomerular lesions ranged from mild mesangial hypercellularity to glomerulosclerosis. Pedigree analysis of affected animals from one herd indicated a strong familial relationship and probable hereditary basis for the syndrome.

Demyelination and remyelination of the caudal cerebellar peduncle of adult rats following stereotaxic injections of lysolecithin, ethidium bromide, and complement/anti-galactocerebroside: a comparative study

Experimentally induced demyelination due to the direct injection of gliotoxic agents has provided powerful models for studying the biology of remyelination. For the most part, these models have involved injection into white matter tracts of the spinal cord. However, the spinal cord has a number of limitations, such as the size of lesions that it is possible to make and its unsuitability for long-term direct cannulation for the delivery of putative remyelination-enhancing agents. In this study, we describe the natural history of three new models of demyelination/remyelination based on the stereotaxic injection of three gliotoxins: lysolecithin, ethidium bromide, and a combination of anti-galactocerebroside antibody and complement (GalC-ab/comp) into the caudal cerebellar peduncle of adult rats. All three agents produced large areas of demyelination with minimal axonal damage, which undergo extensive remyelination. Ethidium bromide- and GalC-ab/comp-induced lesions remyelinated more slowly than those induced by lysolecithin. The contribution to the remyelination of the lesion by Schwann cells reflects the degree of astrocyte damage incurred within the demyelinated area and is greatest for ethidium bromide-induced demyelination. These new models not only provide further insights into the mechanisms of CNS remyelination but also provide a valuable new resource for addressing a series of key issues relevant to current efforts to promote CNS remyelination either by the enhancement of intrinsic processes or by the transplantation of myelinogenic cells.

A presumed inherited spongiform leucoencephalomyelopathy of Romney lambs in New Zealand

This paper records a unique ovine encephalomyelopathy seen on several farms in the Otago Region of New Zealand. It occurred in 2-3 month-old Romney lambs as a rapidly progressive posterior paresis leading to flaccid paralysis. Pathologically, it was characterised by severe spongy vacuolation of white matter in both brain and spinal cord. It is suspected that the condition is inherited.

Spongiform central nervous system myelinopathy in African dwarf goats

A novel spongiform myelinopathy of the central nervous system (CNS) of eleven African dwarf goats was examined by light and electron microscopy. Histological lesions consisted of extensive vacuolation predominantly of the white matter of the diencephalon, midbrain and cerebellar peduncles, as well as of spinal white matter. Ultrastructurally, vacuoles were shown to be intramyelinic, resulting from the splitting of the outer myelin lamellae at the intraperiod line. A few oligodendrocytes showed vacuolar degeneration of cell bodies and processes. Inflammatory reactions were absent. The observed lesions point to an unknown primary damage of oligodendroglia and central myelin. A hereditary background of the disorder is suspected as all investigated dwarf goats were half-brothers or -sisters and partly descended from the mating of adult females with their own sire.

Spinal dysmyelination in new-born brown Swiss x Braunvieh calves

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.