Morphology of Experimental Border Disease of Lambs

Anatomical abnormalities commonly observed in field cases of Border disease (BD) of lambs have been studied in detail in 17 newborn Dorset Horn lambs affected with the experimentally produced disease. Compared with clinically normal control lambs (9), of the same breed and age, the affected lambs were significantly smaller and possessed finer limb bones. Their skulls were shorter, showed excessive prominence of the cranium (doming) and small orbits frequently abnormally positioned in relation to the cranium. The bone of these skulls showed radio-graphically less density, this feature being commonly most evident in the frontal-parietal-temporal area. The study has confirmed dysmorphogenesis as one of the specific features of BD. The greatly variable pattern of morphological lesions in BD and the difficulties which this aspect of the disease creates in its diagnosis in the field are discussed.