418 



Sub-acute Laminitis. 



The few writers who have noticed this form or variety of 

 disease, as well, I believe, as most veterinary practitioners who 

 acknowledge its existence, denominate it chronic ; a denomina- 

 tion I should feel very unwilling to disturb, did I not find it used 

 in senses so dissimilar as to render the true meaning of the term, 

 or that which is intended to be meant by it, at times doubtful. 

 Now and then, chronic implies the stage of comparative inaction 

 which laminitis, whether it be acute or sub-acute, in its progress so 

 commonly runs into ; at other times, it is used to denote the form 

 of disease we are now about to consider, viz. sub-acute laminitis. 

 All this is ambiguous and confounding. In my opinion — and 

 upon this I shall act here — chronic laminitis is but secondary — 

 but a stage or sequel of one or other of the primary forms of the 

 disease; whereas, sub-acute laminitis is an original affection as 

 well as the acute, in relation to which it may be looked upon as a 

 distinct species or variety. According to these views, it is evident 

 that either acute or sub-acute laminitis may end in chronic, but 

 that the acute cannot terminate in the sub-acute disease. 



Characteristic Differences exist between Acute and 

 Sub-acute Laminitis. In neither form is laminitis the disease 

 of the unbroke or unused horse. Now and then, acute laminitis 

 will appear in the four or five-year-old horse fresh taken into 

 work ; more commonly it is seen attacking the horse while he is 

 at work, at the middle period of his life. Sub-acute laminitis, on 

 the other hand, is very apt to select for its subject the aged and 

 worked horse. 2dly. Acute laminitis is the direct and immediate 

 effect of work, hard either from its distressful character or from 

 its endurance : sub-acute, on the contrary, will make its appear- 

 ance in the stable after the -horse has been for some time living in 

 a state of idleness, or indeed absolute rest. 3dly. The former 

 makes its attack directly and immediately, or shortly after, the 

 application of the excitant; whereas the sub-acute disease ap- 

 proaches so gradually and stealthily that it is apt to be present 

 some time before we discover its existence. 4thly. Acute la- 



