仔馬の肋骨骨折をX線と超音波診断装置で比較して診断した論文を読んでみた(17378445)。
To describe clinical, radiographic and ultrasonographic findings related with rib fractures in newborn foals in an equine critical care unit; and to compare diagnostic accuracy of ultrasonography to radiography.
集中治療室の新生仔馬における肋骨骨折の臨床、X線、超音波所見をまとめ、超音波の診断精度をX線と比較すること。
A prospective ultrasonographic study was performed on 29 foals presented to the emergency unit. This study was performed at the Centre Hospitalier Universitaire Vétérinaire (CHUV), University of Montreal. Physical examination as well as radiographic and ultrasonographic examinations were performed.
何らかの原因で集中治療室に入院した29頭の仔馬（平均2.96日齢）。身体検査、超音波検査、X線検査を実施。
Thoracic radiographs revealed 10 rib fractures in 5 of 26 (19%) foals. Ultrasonography revealed 49 fractures in 19 of 29 (65%) foals of which fillies (n = 13; 68%) were significantly over represented as were fractures to the left thorax (n = 15; 78%). Seventeen of 19 foals (90%) had rib fractures located 3 cm or less from the costochondral junction, the distal part of the rib being displaced laterally in all cases. In 2 foals, where both thoracic radiographs and ultrasonography detected rib fractures, the site of fractures was located on the mid portion of the rib. Rib fractures were detected only by thoracic radiographs in one foal. Sixty-five percent (32/49) of fractured ribs had a moderate displacement (1-4 mm).
X線だと26頭中、5頭10本しか骨折を認めなかったが、超音波だと29頭中19頭49本の骨折を認めた。19頭中17頭は肋軟骨との関節から3cm以内に骨折を認め、骨折部より遠位は内側に変位していた。49本中32本は1~4mmの変位であるわずかな骨折であった。
Rib fractures are seen frequently in newborn foals in equine critical care units. Ultrasonography is more accurate than radiography and reveals fractures in most patients presented in emergency. The position (costochondral junction) of rib fractures and of the fragments suggest that most thoracic trauma probably occurs during parturition.
集中治療室に来る仔馬では肋骨骨折は一般的であった。X線より超音波診断の方が正確であった。骨折の部位から考えると、肋骨骨折は分娩の経過中に発生するであろう。
馬の肋骨は18本なので、牛（13本）よりも多い。診断の日齢が若いと、仮骨形成がないので、触診やX線より超音波に頼ることになるのだろうな。図4の、肋骨発生位置は牛と一致している。同じ原因によるものであろう。