TREATING INFECTIOUS MAMMITIS IN THE COW. 
11 
ifest during the whole year, it is most severe in the summer 
months, at a time when the greatest milk production might 
occur. 
In regard to the regional distribution it is worth noting that 
in certain communities the outbreak is so severe as to warrant 
speaking of it as a pestilence. The somewhat increased amount 
of infectious mammitis in the neighborhood of cities may be 
traceable to the more frequent purchase of fresh cows, because 
the period of udder congestion is the most favorable time to 
dispose of an infected animal undiscovered. 
If the location of the infected herds be inscribed upon a map, 
that of the Canton of Zurich,* for instance, it is easy to see that 
certain parts of the canton are subject to a visitation year after 
year in the same manner, while other districts remain unharmed. 
The regions where it is encountered least are those in which 
agriculture is practiced in addition to dairying. These condi¬ 
tions suggest the idea that the strengthening of the constitution 
brought about by the use of dairy animals for labor exerts a 
repressive influence upon the infection. 
Stable infection, i. e ., the repeated appearance of infectious 
mammitis in the course of a year in the same dairy, could be 
authenticated last year in twenty-three cases. 
While in a large number of the isolated sporadic cases the 
means of the introduction of the disease could be recognized, 
yet there were many others untraceable to any visible source of 
infection. 
The occurrence of four outbreaks of stable infection in which 
two to four animals became affected rapidly, one after another, 
* It may be well to call to mind that in this region the disease may, for practical 
purposes, be classified into two types—a curable and an incurable form. The first is caused 
by the short streptococci, which the leucocytes are able to take up and destroy.- The 
incurable form, on the other hand, is associated with long sti'eptococci, which the leu¬ 
cocytes are not able to harm, and which, therefore, remain alive. These streptococci 
apparently wander through the duct of the teat into the milk sinuses, multiply rapidly, 
elaborate toxines which stop the milk secretion and cause the assembling of pus cells in 
the milk sinuses. If the pus cells are allowed to remain undisturbed, they will perform 
their natural function of curing as much as possible. But if they are milked out daily 
their function is interfered with and the cure is hindered or rendered impossible. 
