OCD (Occipital Condylar Dysphsia) is a condition sometimes found in polycerate (many-horned) sheep including Jacobs in which deformed bones at the base of the skull put pressure on the spinal column.
It is sometimes evident in newborn lambs that struggle to walk but can also appear later in the first two years of life. The most common symptom is ataxia (incoordination), often described as “wobbles” which can progress to increasing weakness, inability to eat and eventual death. The only way to diagnose the condition is by x-ray of a live animal or examining the skull after death.
There are two good summaries of the current scientific understanding of OCD, a 2022 paper written by University of Georgia faculty in the Journal of the American Veterinary Medical Association [Journal of the American Veterinary Medical Association] Pathology in Practice (1).pdf and a 2017 paper by Irish researchers in the Open Veterinary Journal OVJ-2016-09-042 A.M. Lee et al OCD.pdf Both of these papers have detailed descriptions of the condition and photos showing the impacts of deformed spinal columns in affected sheep.
Ohio breeder Sara Karr shared skull photos of a ram lamb with suspected OCD. Sarah says “I usually describe the OCD gait as "drunken", with a lot of swaying until eventually they are unable to rise.”
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