322 VETERINARY HYGIENE 



mitis. The researches of Savage have shown that the streptococcus 

 commonly found in cases of sore throat, though similar morpho- 

 logically, &c., possesses several points of difference from the strep- 

 tococcus commonly associated with bovine mastitis. The disease 

 is an important one not only from the possible danger to human 

 beings, but also from the loss of milk and depreciation in the value 

 of the cow owing to the fact that the affected quarter rarely, if 

 ever, regains its normal usefulness. 



Outbreaks of mammitis of a marked contagious nature have 

 been reported on many occasions, the type of the disease being 

 usually chronic. This form of mammitis is also produced by 

 streptococci. At times the first indication that there is anything 

 wrong is received from the person purchasing the milk. In early 

 cases the milk may appear to be normal on leaving the udder, but 

 on standing it shows a curdy deposit and may give off a rather 

 offensive odour. As the disease progresses the deposit becomes 

 much more abundant, and the supernatant liquid becomes whey- 

 like. This state of affairs usually follows the introduction of a 

 fresh purchase, and the disease may have spread to several 

 other cows before its existence is realised. In one such outbreak 

 described by Radway* the disease was so persistent that it was only 

 eradicated by slaughtering all the milking cows and thoroughly 

 disinfecting the byres. 



The mortality is variable, often being very high in some out- 

 breaks of acute mammitis. The period of incubation varies accord- 

 ing to the type of the disease. It may be only 2 or 3 days in acute 

 mammitis, while in chronic mammitis it may be as many months 

 (Begg).f The disease results from direct inoculation of the udder 

 with pathogenic organisms and is frequently spread by the hands 

 of the milker. Except in cases of tuberculous mammitis, the 

 inflammatory condition of the udder is thus a primary one. As 

 Begg points out,$ it is surprising that mammitis is not more 

 common. The udder is a highly vascular organ and is subject to 

 traumatism from tramps and horn gores ; too frequently it is caked 

 with dung and is often in constant contact with faeces and urine, 

 or with purulent discharges derived from the uterus or drawn from 

 a diseased quarter. It is delicate in structure, and is easily injured. 

 Lastly, the milk in the sinuses is an excellent culture medium and at 

 an ideal temperature for bacterial growth. Begg draws attention 

 to the connection between suppurating sores on the feet of cattle 

 *Journ. Comp. Path., 1902, Vol. XV., p. 361. 



f Wallis-Hoare, System. Vet. Med., 1913, Vol. I., p. 387. 



$ Wallis-Hoare, System. Vet. Med., 1913, Vol. I., p. 375. 



