Occipital condylar dysplasia in a Jacob lamb ().

Jacob sheep () are a pedigree breed known for their "polycerate" (multihorned) phenotype. We describe a four-horned Jacob lamb that exhibited progressive congenital hindlimb ataxia and paresis, and was euthanased four weeks post-partum. Necropsy and CT-scan revealed deformity and asymmetry of the occipital condyles, causing narrowing of the foramen magnum and spinal cord compression.