ON DORSO-LUMBAR SPRAIN IN THE HORSE. 39 
processes of the vertebra cover completely the articular pro¬ 
cesses of the following vertebra, while the vertebra? themselves 
tend to separate one from another by their bodies. Pression 
re-acts upon the intervertebral discs, which, under its influence, 
become thicker at their inferior than at their superior parts. 
Thus pressed upon, the vertebral chain describes the arc of a 
circle whose convexity is below. 
At the moment I am writing I have upon my table several 
specimens of diseased spines, and one among them presents the 
curvature in the opposite direction to what I have described.* 
Indeed, what I have said is so true, that ossifications and osseous 
stalactites uniformly make their appearance in the dorsal 
region, along the inferior parts of the bodies of the vertebrae. 
In the lumbar vertebrae they commonly come upon the sides, 
and sometimes, though rarely, at the bottom as well. 
If the force of pression acts by slow degrees on a young 
horse, we can easily understand how it happens that such 
animal, although well made originally, becomes in time hollow- 
backed. We have had for several years past a horse under 
our eye who has furnished us with a good example of it. 
In an adult horse changes of the kind mentioned may, under 
similar circumstances, take place without our being at all from 
any external appearance aware of their existence. In regard 
to this, 1 have remarked that when the use made of horses 
about Paris was different from what it is at present, many cases 
of ossification of the spine came under our notice among the 
subjects sacrificed for the purposes of the College. But since 
vehicles have been in use for transporting merchandise to the 
different markets in Paris, in place of transporting it upon 
horses’ backs, such lesions have been rarely met with. 
Supposing, however, on the other hand, that this force of 
pression comes to act all at once, is it surprising that it should 
produce more than stretching, more serious lesion, such as rup¬ 
ture of the intervertebral discs, or even fracture of the vertebral 
chain. M. H. Bouley and myself have witnessed an example of 
this taking place even under our own eyes, in a horse drawing 
an overloaded carriage, the axletree of which broke : the animal 
died immediately after the accident. And I could mention 
other analagous cases. 
* Several examples stand on record of deviation of the dorso-lumbar spine. 
Girard, junior, saw a congenital instance of it in a mare some years old. (Rec. de 
Med. Vet. 1824, p. 145.) M. Pouchy has likewise given an example of it under 
the title of : Observations on an extraordinary Anomaly of the Dorsal and Lumbar 
Vertebrce in a Yearling of strong Constitution. (Memoirs of the Veterinary Society 
of the Provinces of Calvados and de la Manche, 11 th Year , No. 8 , p. 104.) This 
case has no relation to strain of the reins. 
In April last, I saw at Neubourg a mule with a double curvature of the dorso- 
lumbar spine, from below upward and from before backward ; but I was unable to 
learn any particulars about the animal. 
