Neuritis of the cauda equina in a dog.

This study presents the first case report of neuritis of the cauda equina in a dog, including characterisation of the inflammatory infiltrate. The dog in question, a 6-year-old Welsh springer spaniel, was presented with flaccid tail and faecal and urinary incontinence. The histological lesions included severe mononuclear cell infiltration of the nerve roots of the cauda equina and of the lumbar nerve roots. The infiltrate was composed of large numbers of T-lymphocytes and B-lymphocytes and small numbers of macrophages. Polymerase chain reactions of brain and spinal tissues were positive for Neospora caninum.

Radiculomeningomyelitis due to Halicephalobus gingivalis in a horse.

An adult horse was euthanatized following a clinical diagnosis of cauda equina neuritis. Significant gross postmortem and histopathologic findings were limited to the sacral spinal cord and cauda equina. The sacral spinal cord, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained numerous nematode larvae and fewer adults with a rhabditiform esophagus having a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic and didelphic with reflexed ovaries. These morphologic features confirm Halicephalobus gingivalis as a novel cause of clinical signs in this case of cauda equina neuritis.

Stability and plasticity of primary afferent projections following nerve regeneration and central degeneration.

Sensory neurons of the dorsal root ganglia (DRG) regenerate their peripheral axons with relative ease following a nerve lesion. The capacity for central regeneration appears more limited. However, after nerve lesion, some DRG neurons gain a regenerative advantage to sprout centrally. We developed a lesion model in the rat to test whether, after prior lesion of their peripheral axons, subsets of cutaneous afferents benefit differently in their ability to sprout into adjacent spinal segments denervated by dorsal rhizotomy. We found that under identical circumstances, myelinated sensory neurons, small-diameter peptidergic sensory neurons containing calcitonin gene related peptide (CGRP), and small-diameter nonpeptidergic neurons that bind the lectin from the plant Griffonia simplificolia, isolectin B4 (IB4) differ dramatically in their ability to regenerate centrally. Myelinated afferent terminals labelled transganglionically with cholera-toxin beta-subunit gain a small advantage in collaterally sprouting into the adjacent denervated neuropil in lamina III after prior peripheral nerve lesion. This central regenerative response was not mimicked by experimentally induced inflammation of sensory neuron cell bodies. Intact and unlesioned sensory neurons positive for CGRP sprout vigorously into segments denervated by rhizotomy in a nonsomatotopic manner. In contrast, IB4-positive sensory neurons maintain a somatotopic distribution centrally, which is not altered by prior nerve lesion. These data reveal a remarkably heterogeneous response to regeneration-promoting stimuli amongst three different types of cutaneous sensory neurons. In particular, the divergent responses of peptidergic and nonpeptidergic sensory neurons suggests profound functional differences between these neurochemically distinct neurons.

Pathological findings of nude mice inoculated with bovine Neospora.

Nude mice were infested with bovine Neospora by intraperitoneal inoculation of the brain and spinal cord from an aborted bovine fetus due to neosporosis. Inoculated mice showed severe emaciation and tetraplegia at about 2 to 4 months post-inoculation. Histopathologically, polyradiculoneuritis and peripheral neuritis were the major findings, and lesions in the central nervous system were located at periventricular and submeningeal areas of the cerebrum or at the white matter around the roots of radices of the spinal cord. These findings may suggest the protozoa inoculated into the abdominal cavity invaded the spinal cord via the spinal nerve and later reached the brain through the cerebrospinal fluid.