A Novel Movement Disorder in Related Male Labrador Retrievers Characterized by Extreme Generalized Muscular Stiffness

Vanhaesebrouck, A.E., Shelton, G.D., Garosi, L., Harcourt-Brown, T.R., Couturier, J., Behr, S., Harvey, R.J., Jeffery, N.D., Matiasek, K., Blakemore, W.F. and Granger, N. (2011) A Novel Movement Disorder in Related Male Labrador Retrievers Characterized by Extreme Generalized Muscular Stiffness. Journal of Veterinary Internal Medicine, 25 (5). pp. 1089-1096. 10.1111/j.1939-1676.2011.0757.x.

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DOI: 10.1111/j.1939-1676.2011.0757.x

Abstract

Objectives: To describe the clinical phenotype of a new motor disorder in Labrador Retrievers. Animals and Methods: Case series study. Seven young male Labrador Retrievers presented for evaluation of stiff gait. Results: All affected dogs had generalized muscular stiffness, persistent at rest and resulting in restricted joint movements. They showed a forward flexed posture, festinating gait, and bradykinesia. Signs developed between 2 and 16 months of age and tended to stabilize in adulthood. Needle electromyogram in the conscious state showed continuous motor unit activity in resting epaxial and proximal limb muscles. This activity was abolished by general anesthesia. Muscle and nerve histopathology was normal. In 2 dogs necropsied, astrocytosis was evident throughout the spinal cord gray matter, reticular formation and caudate nuclei. Decreased neuronal counts were selectively found in the spinal cord Rexed's lamina VII, but not in VIII and IX. Pedigree analysis showed that the affected dogs were from 5 related litters. Conclusions and Clinical Importance: This new hypertonicity syndrome in Labrador Retrievers is unique because of the selective distribution of the histological lesions, the lack of progression in adulthood, and its exclusive occurrence in male dogs. Pedigree analysis suggests an X-linked hereditary disease, although other modes of inheritance cannot be ruled out with certainty. We hypothesize that altered output from basal nuclei and reticular formation together with motor neuron disinhibition caused by a decreased number of spinal cord interneurons leads to the muscular stiffness.

Item Type:Article
Uncontrolled Keywords:Canine;Central nervous system;Muscle stiffness;Rigidity
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:2292
Journal or Publication Title:Journal of Veterinary Internal Medicine
Deposited By:Library Staff
Deposited On:06 Oct 2011 10:05
Last Modified:06 Oct 2011 10:05

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