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ACUTE INFLAMMATION OF THE UDDER. 
lines, but further study and the discovery of the exact cause in each 
case can alone enable us to divide clinically similar conditions. Until 
such discoveries have been made we shall still remain ignorant of why 
one attack remains of a trifling character and recovery soon follows while 
another leads to gangrene and death. Despite the numerous and deeply 
interesting researches of the last few years an aetiological classification 
still seems impossible. 
We are therefore compelled to adhere to the clinical standpoint. The 
old view, however, that there was only one mastitis with varying causes 
and results is no longer tenable, and the division here adopted is based 
on the course and results of the different attacks. Needless to say it 
must immediately yield place to any mode of grouping which better 
satisfies practice and theory. 
During lactation acute inflammation of the udder is most common, but 
at other times isolated cases are seen, and under very rare circumstances 
inflammation of the udder has been noticed in virgin cows. Guillebeau 
says that cows, most frequently suffer from mammitis between the 5th 
and 6th year, and that the majority of attacks (nearly two-thirds) occur 
in the first four months after parturition; the greatest number of these 
soon after the act. 
The physiological activity of the milk glands in many respects favours 
the development of inflammation. The early processes of lactation, 
particularly the congestive stage, so closely resemble acute inflammation, 
even in their outward manifestations, that it is difficult to draw a sharp 
line between the two, and the inflammatory non-infectious oedema noticed 
by Kitt is probably of this nature. Both the vascularity of the gland 
and the processes necessary for the development of secretory activity 
clearly favour the appearance of disturbances which readily take on 
an acute inflammatory character. It is, therefore, very natural that 
most diseases of this kind occur during the years of parturition. 
The anatomical formation also favours acute inflammation. The milk 
forms an excellent cultivating medium for bacteria, to which the ducts 
offer an easy point of entrance. Finally, the position of the udder is 
exceedingly favourable to the entrance of infectious material; and as 
injuries to the skin of the udder, and especially to the teats, are frequent 
in animals, they easily form the point of origin for infectious inflammation. 
The causes of acute inflammation may be divided into mechanical, 
chemical, thermal, and specific. In cattle the first takes the form of 
horn thrusts and similar injuries; large udders may be trodden on by 
other animals, or by the cow herself when rising. This division there¬ 
fore includes bruises and wounds, as already described. 
Chemical or thermal irritants are much less frequent, though the 
milk may undergo changes within the udder ; irritant substances form 
