92 PERIODIC OPHTHALMIA. 



although, to the common observer, the animal, from eating and 

 drinking with his usual appetite, may perhaps appear undisturbed 

 in health, the professional man detects a sharp febrile pulsation, 

 and a mouth hotter than natural ; the tongue drier : the bowels 

 somewhat costive ; the urine less and higher coloured ; and at his 

 work — at which the horse is frequently continued, notwithstanding 

 his ophthalmia — he is found to be weak, and to sweat under less 

 exertion. And yet the animal, as I said before, evinces no very 

 evident sign of feeling unwell ; or none, at least, that seems to be 

 heeded by his groom or master, whose attention is wholly en- 

 grossed by the " weak" eye. D'Arboval has remarked, that when 

 one eye by itself is affected, the pulse on that side is harder and 

 fuller than on the side of the healthy eye. 



The Duration of a Paroxysm of Ophthalmia will be found 

 to vary very considerably. First attacks, and commonly second 

 and even third attacks, will occupy a period of from ten days to a 

 fortnight : I knew them, in two instances, to extend to a term of 

 forty-one days. But when the disease comes to relapse frequently, 

 and run from one eye to the other, the paroxysm will now and then 

 prove extremely short : in three or four or five, sometimes even in 

 two days after setting in, all will be over again : and in these 

 fugacious visitings, of course, there is nothing like remission 

 observable. 



Varieties of this ophthalmia are distinguishable. Sometimes 

 it assumes an acute^ nay, even a virulent form; oftenest, however, 

 the sub-acute character. In cold and wet seasons I have seen the 

 disease endemic, attacking horses in certain exposed situations. It 

 is certainly neither infectious nor contagious ; nor have I myself 

 ever known it prevalent enough to be called an epidemic. 



The Progress, irregular, interrupted, destructive though it 

 ma}^ be called, yet cannot, in the generality of cases, be said to be 

 rapid : on the contrary, the inflammation, as I have just observed, is 

 commonly of the sub-acute type, with that Protean phasis which 

 one day holds forth the 



" Promise to our sight to break it in our hope." 



Cases, however, do every now and then occur, rare though they 

 be, in which the inflammation is of that unequivocal and violent 



