ON DORSO-LUMBAR SPRAIN IN THE HORSE. 41 
accident occurred in a manner directly opposite to that in which 
it is produced under the influence of pressure from above down¬ 
ward. The vertebral chain in the case under consideration 
tends to form an arc whose convexity is superiorly, so that 
one might almost say that the fracture was produced by crush¬ 
ing, or through concentration of effort upon the central part of 
the arc, represented by the bodies of the vertebrae. 
At a time when a horse’s legs are shackled all close together, 
it is truly surprising that this accident (in casting) does not 
happen oftener than it does. 
Before I close this division of my subject, I will add Gar- 
sault’s opinion on these accidents :— 
“ The pairs of muscles, called spinales el semi-spinales dorsi, 
are subject to receive harm from horses being too quickly un¬ 
saddled at a time when they are hot, in consequence of taking 
cold and becoming relaxed to a degree depriving them, in some 
measure, of feeling and motion. This accident happens more 
commonly among old and lean horses, with whom, from their 
weakness in the abundance of their phlegmatic humours, these 
muscles are often so much relaxed that they can hardly drag 
their bodies along.” 
Pathological Anatomy. 
Let us now inquire into the lesions the consequence cf such 
causes. 
The diseases manifested exteriorly by tour de bateau (brcken 
back) are numerous enough, while the authors who have engaged 
in this question of pathology make us sensible enough of it by the 
different names they have made use of, and the various descrip¬ 
tions they have handed down to us. 
Garsault (in the work afore-mentioned) says, that sprained 
reins is oftener a relaxation of the spinal muscles than a dislo¬ 
cation of the vertebrae. 
Other authors of less ancient date (Bourgelat and Vitet) have 
ascribed the symptoms to luxations and fractures of the ver¬ 
tebrae ; or, finally, to straining of the ligaments uniting the 
different pieces of ,the vertebral chain. In this last case it is 
that one may say that the animal has dorso-lumbar sprain , or 
sprain of the reins. The same authors attribute also to this, 
manifestation of contraction, more or less violent, of the muscles. 
Rigot, who has reported two cases of these accidents, believes 
he has discovered that the lesions causing broken back are of a 
very different description from any we have seen. 
Case I. is that of a harness horse, who was brought to be 
destroyed for the purpose of dissection. Having subjected him 
to examination, in order to ascertain what had rendered him 
unserviceable, I felt convinced that he was labouring under 
VOL. XXV. G 
