Variola : Cowpox. 345 



A succession of vesicles often appear on the same animal, so 

 that they may be found in all different stages of vesicle, pustule 

 and crust on the same bag at one time. The later eruptions may 

 be the result of inoculation from the earlier ones, and tend to pro- 

 long the attack materially. 



In inoculation of the bovine animal for the production of lymph 

 for vaccination, the skin of the abdomen from the symphysis 

 pubis to the umbilicus is shaved, or in other cases the skin be- 

 tween the thighs, or in still others the skin on each side over the 

 loins, and the virus applied in 50 to 200 points, by preference 

 scraped until liquid oozes, but without any escape of blood. In 

 a warm room the eruption matures in four or five days, its form 

 taking on an appearance approximating that seen on the hairy 

 skin of the horse. The individual lesions are somewhat extended 

 corresponding in form and .size to the abrasion on which the 

 lymph was applied, and usually present the appearance of a raised 

 patch, covered by a grayi.sh film of epidermis, on the removal of 

 which there is seen a raw alveolated surface filled with the amber- 

 colored lymph. 



Differential Diagnosis. From aphthous fever, cowpox is clearly 

 distinguished by (a) the multilocular structure of the vesicle, 

 while that of aphthous fever is a single undivided cavity which 

 can be drained completely by a single needle prick ; (b) by the 

 pitting or umbilication, the aphthous vesicle being uniformly 

 rounded and convex ; (c) by the absence of vesicles or sores on 

 the mouth and feet, which are rarely wanting in the aphthous 

 eruption ; (d) by the comparative absence of hyperthermia and 

 constitutional disturbance, which is better marked though still 

 slight in aphthous fever, and (e) by the absence of the intense and 

 subtle infection of aphthous fever, which quickly attacks a whole 

 herd and extends with equal rapidity over sheep, goats and pigs, 

 attacking all cloven-footed animals virtually without exception. 

 The cowpox patient, on the contrary, does not necessarily attack 

 the cow in the next stall unless milked by the same hands, and 

 spares heifers, bulls, steers, sheep, goats and pigs. 



From the rinderpest cutaneous eruption it is easily distinguished 

 by the presence of lymph in the lesion, that of rinderpest being a 

 mere epidermic concretion ; by the absence of the intense fever, 

 anorexia and general constitutional disturbance, and of the early 



