Abstract.A polyneuropathy recognized in mature Rottweiler dogs is characterized by paraparesis that progresses to tetraparesis, spinal hyporeflexia and hypotonia, and appendicular muscle atrophy. Although signs may appear acutely, the course tends to be gradually progressive (up to 12 months or longer in some dogs) and may be relapsing. Nerve and muscle biopsies were examined from eight affected Rottweilers (six male and two female) between ages 1.5 and 4 years. Pronounced neurogenic atrophy was present in skeletal muscle samples. Changes in sensory and motor peripheral nerves included loss of myelinated nerve fibers, axonal necrosis, and variable numbers of fibers with inappropriately thin myelin sheaths. Ultrastructural findings included myelinated fibers showing myelinoaxonal necrosis, demyelinated fibers often associated with macrophage infiltration, many axons with myelinlike membranous profiles. increased endoneurial collagen, occasional axonal atrophy, and numerous Bungner bands. Lesions in unmyelinated fibers included increased numbers of Schwann cell profiles and loss of axons in Schwann cell subunits. Morphologic and morphometric studies indicated preferential loss of medium (5.5-8 pm) and large (8.5-12.5 pm) fibers. which was more severe in distal parts of nerves than in more proximal regions and nerve roots. The cause was not determined; however, histopathologic studies suggest this condition is a dying-back distal sensorimotor polyneuropathy that has morphologic and morphometric similarities to hereditary motor and sensory neuropathy (HMSN) type I1 in humans.Key words: Animal model; distal axonopathy; dogs; dying-back polyneuropathy; HMSN type 11; morphometry; muscle; nerve; teased fibers; ultrastructure.Several neurologic abnormalities have been reported in Rottweiler dogs, including leukoencephalopathy in mature dogs,34.49.55 neuroaxonal dystrophy in immature and mature dogs,20.21.32 an isolated case of polyneuritis in a mature dog,' and spinal muscular atrophy, an abiotrophy that occurs in young Rottweiler puppies around 4-6 weeks of age.47.48 In this article, we report another neurologic disorder in this breed, a progressive degenerative polyneuropathy with a distal axonal distribution, that has been found to date only in mature Rottweilers. Materials and MethodsEight mature Rottweilers (six male and two female) between ages 1.5 and 4 years were studied for progressive neurologic disease. There was no historic evidence of any dog being exposed to a toxic substance. Clinical signs were characterized by paraparesis that progressed to tetraparesis, spinal hyporeflexia and hypotonia, and appendicular muscle atrophy in distal limb muscles. Dogs typically developed a plantigrade stance associated with a crouched, waddling gait. Cranial nerve function was normal. Sensory deficits were not detected in any dog. Although signs appeared acutely in two dogs. the clinical course typically was slowly progressive (up to 12 months or longer in some dogs). In three dogs, the clinical course was relapsing, and al...
Forty-three children (aged 7 to 62 months) with protein calorie malnutrition (PCM) were studied; 13 had mild to moderate PCM and 30 severe PCM. A reduction of motor nerve conduction velocity and abnormalities of sensory conduction were present in both groups. The abnormality of motor nerve conduction was directly related to the severity of PCM and the presence of hypotonia and/or hyporeflexia. Sural nerve biopsies from both groups were studied for myelinated fibre density, fibre size spectrum, relationship of internodal length with diameter and qualitative light microscopic changes. The biopsies from children with mild to moderate PCM were characterized by a normal developmental change in myelinated fibres with an increasing proportion of medium and large size fibres, a transition from a unimodal to a bimodal distribution and an appropriate relationship of internodal length to fibre diameter. Evidence of mild segmental demyelination was observed in only one patient of this group. In contrast, in the biopsies from children with severe PCM, the normal developmental pattern for myelinated fibre size distribution was impaired with a persistence of small myelinated fibres, and there was a failure of internodal segments on large fibres to elongate with increase in age and significant segmental demyelination in about 50 per cent of cases. Retarded myelination and segmental demyelination probably form the morphological basis for impaired peripheral nerve function in PCM. Short internodes on large diameter fibres may also contribute to this effect.
Erythrocyte membranes and their liposomes were prepared from clinically normal dogs and Labrador retrievers with hereditary muscular dystrophy. The "static" and "dynamic" components of fluidity of each membrane were then assessed by steady-state fluorescence polarization techniques using limiting hindered fluorescence anisotropy and order parameter values of 1,6-diphenyl-1,3,5-hexatriene (DPH) and fluorescence anisotropy values of DL-2-(9-anthroyl)-stearic acid and DL-12-(9-anthroyl)-stearic acid, respectively. Membrane lipids were extracted and analyzed by thin-layer chromatography and gas chromatography. The results of these studies demonstrated that the lipid fluidity of erythrocyte membranes, and their liposomes, prepared from dystrophic dogs were found to possess significantly lower "static and dynamic components of fluidity" than control counterparts. Analysis of the composition of membranes from dystrophic dogs revealed a higher ratio of saturated fatty acyl chain/unsaturated chains (w/w) and lower double-bond index. Alterations in the fatty acid composition such as decrease in levels of linoleic (18:2) and arachidonic (20:4) acids and increase in palmitic (16:0) and stearic (18:0) acids were also observed in the membranes of dystrophic animals. These associated fatty acyl alterations could explain, at least in part, the differences in membrane fluidity between dystrophic and control dogs.
Abstract. Serial peripheral nerve biopsies from two golden retriever littermates with chronic neurologic disease were taken for morphologic and morphometric evaluation. Teased nerve preparations were difficult to interpret due to the lightness of myelin staining. Light and electron microscopic findings were characterized by the following: reduced number of myelinated axons, presence of myelinated sheaths inappropriately thin for the caliber of the fiber, poor myelin compaction, increased numbers of Schwann cell nuclei, increased concentration of neurofilaments in myelinated axons, many Schwann cells with voluminous cytoplasm, and increased perineurial collagen. Onion bulb formation was not seen. In contrast to control data, a poor correlation was seen between numbers of myelin lamellae (ML) and axonal circumference (AC). The frequency distribution of ML ranged from 5 to 55 lamellae in affected animals (mean, 28 lamellae) compared to 20 to 140 lamellae in controls (mean, 66 lamellae). The MWAC ratio was significantly reduced (P < 0.001) in nerves of affected dogs.Morphometric results indicated that fibers of all calibers were hypomyelinated.Abnormal myelination of the nervous system has been reported in a variety of animal species,9,14,16,21,32 including a number of dog breeds springer spaniels,2o lurcher weimaraner^,^^ Samoyeds,I3 and a DalmatianIs). Heredity has been implicated as the cause of canine hypomyelinating conditions. In all of these breeds, hypomyelination involved the central nervous system, and peripheral nerves were normal.In the present report, severe hypomyelination of the peripheral nervous system is described for the first time in two golden retriever littermates. Materials and MethodsTwo golden retriever littermates, one male and one female, were studied from 7 weeks to 5 months of age. Both dogs were initially presented for hind limb ataxia at 7 weeks of age. One other littermate from the litter of seven was reported to be slightly affected but was not examined. Both dogs had a crouched stance, mild pelvic limb atrophy, and weakness. Circumduction was evident in the pelvic limbs when walking, and a "bunny hop" gait was present when running. Segmental reflexes were depressed or absent in pelvic limbs of both dogs and in thoracic limbs of the male. Motor nerve conduction velocities were markedly reduced in sciatic-tibia1 and ulnar nerves. Needle electromyographic studies revealed rare denervation potentials in a few muscle groups (M.E. Matz et al., unpublished observations).Under general anesthesia, 2-cm fascicular segments of common peroneal nerve at the level of the stifle were removed, stretched on wooden tongue depressors with pins, 21 and fixed in a mixture of 4% formalin/l% glutaraldehyde. After fixation for 12 hours, nerve samples were divided into halves and washed in Millonig phosphate buffer (pH 7.3) at 4 C overnight. One half was post-fixed in 1% osmium tetroxide for 6 to 8 hours. These samples were then placed in 66% glycerin for 24 hours and stored in 100% glycerin for single teas...
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