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April 2012

Limbs: arthrogryposis multiplex congenita; neck: torticollis; vertebral column: kyphosis

History: Lamb, Abortion.

Diagnoses: Limbs: arthrogryposis multiplex congenita; neck: torticollis; vertebral column: kyphosis

Description:

The posture of the lamb could not be changed even by application of force due to stiffness of the joints and neck. Especially the forelimbs were hyperflexed and the neck twisted. The vertebral column was deformed by kyphosis.

Comments:

The lamb was one of many aborted or stillborn lambs in the current lambing season. Molecular analysis revealed the presence of Schmallenberg-Virus (SBV) in the affected herd. This new viral strain belongs to the family of Bunyaviridae, genus Orthobunyaviridae and induces a congenital arthrogryposis-hydranencephaly-syndrome. This teratogen virus primarily targets neuroblasts and motoneurons. Damage to ventral motor neurons in the spinal cord leads to impaired intrauterine stimulation and development. Secondary atrophy of skeletal muscles results in hypomobility of the developing fetus, followed by arthrogryposis and other malformations of the skeleton.

Typical macroscopic lesions include diverse skeletal malformations like arthrogryposis, torticollis, deviation of symmetry of the skull, and brachygnathia inferior. Additionally, hypoplasia of the cerebellum and spinal cord as well as a marked hydranencephaly can be seen.

Picture by: Kristina Dietert, Department of Veterinary Pathology,
Freie Universit├Ąt Berlin, Germany

Author: Kristina Dietert, Department of Veterinary Pathology,
Freie Universit├Ąt Berlin, Germany