The mean ages of 10 calves with tracheal collapse were 2.7 weeks at onset of clinical signs and 9.4 weeks at presentation for treatment. Inspiratory and expiratory dyspnea and stunted growth were the most common clinical signs. There were abnormalities of the cranial ribs consistent with healing fractures with redundant callus in eight lateral thoracic radiographs. Tracheal collapse in calves may result from cranial thoracic trauma during or soon after birth. Short polypropylene ring prostheses made from 60 ml syringe barrels were placed on the tracheas of four calves with cervical tracheal collapse. There were cranial rib masses in all calves and resection of the right first and second ribs was necessary in one calf to allow placement of prostheses. Dyspnea was relieved in all calves. One calf died of unrelated causes in year 3, and one calf had recurrence of clinical signs at month 5 and was euthanatized. In both calves, tracheal stenosis resulted from continued growth and infolding of the trachea within the constraints of the prostheses. One calf was alive at month 11, and one calf died of acute bronchopneumonia on day 2. Removal of tracheal prostheses in calves is recommended after 2 to 3 months if clinical signs recur.

Summary Nineteen Brown Swiss calves affected with spinal muscular atrophy were described. Weakness of the rear legs was the first sign observed at 3 to 4 weeks of age. Terminal stages were characterized by severe muscular atrophy, quadriparesis, and sternal recumbency. Bronchopneumonia was a frequent complicating disease. Microscopic changes consisted mainly of degeneration and loss of motor neurons in the ventral horns of the spinal cord. Neurogenic atrophy of muscles was a constant finding. Electron microscopy revealed accumulation of neurofilaments and mitochondria in affected neurons. The disease shares many features with Werdnig‐Hoffmann disease in man and the spinal muscular atrophies of other animals. Zusammenfassung Spinale Muskelatrophie bei Schweizer Braunvieh‐Kälbern Es werden 19 Schweizer Braunvieh‐Kälber mit spinaler Muskelatrophie beschrieben. Als erstes Symptom trat im Alter von 3–4 Wochen Hinterhandschwäche auf. Für das terminale Stadium waren schwere Muskelatrophie, Lähmungen der vier Extremitäten und sternales Festliegen charakteristisch. Als zusätzliche Krankheit trat häufig eine Bronchopneumonie auf. Die mikroskopischen Veränderungen bestanden hauptsächlich in Degeneration und Verlust von Motoneuronen in den Ventralhörnern des Rückenmarkes. Immer wurde eine neurogene Muskelatrophie beobachtet. Elektronenmikroskopisch war in den betroffenen Neuronen eine Akkumulation von Neurofilamenten und Mitochondrien erkennbar. Die Krankheit entspricht in vielen Merkmalen der Werdnig‐Hoffmannschen Krankheit des Menschen sowie spinalen Muskelatrophien anderer Species.

Abstract. Twenty-five syndactylous Angus cattle, characterized pathologically, were reported from 16 herds in 10 states from 1979 to 1994. Twenty-one (84%) had all 4 legs syndactylous, 3 (12%) had 3 legs syndactylous, and 1 (4%) had 2 legs syndactylous. All syndactylous cattle walked with considerable difficulty. Hooves of aged animals became curled and bent laterally or medially. Affected hooves had the appearance of a truncated cone, the base of which was located at the coronary band. Most hooves were fused completely with no indication of dual anlage. An occasional hoof had a distal notch, and other hooves had a dorsally located groove indicating dual embryonic origin. Lateral dewclaws were enlarged in most cases. Radiographs and dissections of limbs of 19 animals revealed a consistent pattern of fusion in most affected calves. Lesions included 1 or more of the following: disappearance of the large metacarpal and metatarsal intertrochlear notches, horizontal fusion of 1 or more carpals and tarsals, fusion of proximal sesamoids, 1 distal sesamoid, and fusion of paired phalanges. Evidence of a genetic cause consisted of 11 syndactylous calves among 70 offspring of 4 3/4 sib families, 8 preterm syndactylous fetuses among 148 preterm fetuses and 13 calves in progenies of 19 animals tested for possible heterozygosity, and 5 syndactylous calves from matings of an Angus syndactylous bull with 1 Angus and 4 Holstein syndactylous cows. Data were consistent with recessive inheritance at a single locus. Angus cattle with sydactytly had a larger number of affected limbs than did syndactylous Holsteins and their Angus crosses, suggesting existence of 2 recessive alleles. The allele of Holsteins (sy H ) appeared to influence phenotypic expression in a dominant pattern over the Angus allele (sy A ). Both sy A and sy H alleles acted as reccessives to the normal SY allele. Phenotypic effects on limb development were most dramatic in calves with the sy A /sy A genotype.

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