[Spinal muscle atrophy in Brown Swiss x Braunvieh cross calves]

The report describes seven SMA-cases in descendents of crossbreeds of American Brown Swiss x Deutsches Braunvieh. Symptoms and course: After initially normal development of the calves for one to six weeks the disease set in suddenly followed by a rapid lethal course of one to one and a half weeks duration due to asphyxia and/or secondary diseases. Only one case was reported having been sick since birth (?). Characteristic signs were rapidly progressing muscular atrophy, paresis and paralysis of the limbs, the trunk and the diaphragm, usually accompanied by progressive dyspnoea. Signs of congenital neuromyodysplasia (arthrogryposis) of different degree were present in four of the seven calves. Six calves had contracted a secondary pneumonia. Blood gas analysis (6/7) revealed a compensated (1x) or decompensated (4x) respiratory acidosis. Neurohistological findings: Degeneration and loss of motor neurons in the ventral horns of the spinal cord and neurogenic muscular atrophy. Immunohistochemistry revealed a pronounced accumulation of type 200 kD-neurofilaments in perikarya and dendrites of ventral horn motoneurons indicating disturbed mechanisms of the axonal transport. The disease seems to be inherited as a recessive trait.