VII 



TUBERCULOSIS OF THE COW 133 



It is evident from these facts that veterinary inspection 

 of cows, even if repeated frequently and conducted by officers 

 of the highest clinical skill, is, apart from bacteriological 

 examination, a safeguard which is insufficient to prevent 

 tubercle bacilli from gaining access to the milk. 



That extremely small quantities of milk from cows suffering 

 from udder tuberculosis may set up tuberculosis in guinea-pigs 

 is shown by the investigations of Ostertag, Ostermann, etc. 

 Ostertag 1 tested the milk of ten cows suffering from udder 

 tuberculosis as regards its capacity to set up tuberculosis 

 when inoculated into the guinea-pig. In every case the un- 

 diluted milk set up the disease, while dilutions of the milk as 

 great as 1:10 million, 1:1000 million, 1 : 10,000 million 

 set up tuberculosis in guinea-pigs in individual cases. Oster- 

 mann 2 tested the milk of two tuberculous cows. With the 

 milk of the first cow dilutions of 1 : 1000 and 1 : 5000 set 

 up tuberculosis, but dilutions of 1 : 10,000 and over were 

 ineffective. With the milk of the second cow dilutions of 

 1:5000, 1:10,000, and 1:50,000 were positive, while 

 1:25,000 was negative. 1 c.c. of the dilution was in- 

 oculated in each case. Delepine records that 0'0002 c.c. 

 of milk from a cow with advanced udder tuberculosis set up 

 tuberculosis in a guinea - pig. Greater dilutions were not 

 tried. 



These results show the variable number of bacilli in cases 

 of udder tuberculosis, and the very large numbers which may 

 be present. 



The detection of bovine tuberculosis may be carried out 

 in three ways : clinical examination, bacteriological diagnosis, 

 and by the use of tuberculin. 



Clinical Diagnosis. This is not the place to discuss the 

 symptoms of tuberculosis in cows, and books on veterinary 

 practice must be consulted. The clinical diagnosis of all but 

 well-marked cases is generally recognised as impracticable. 

 As one veterinary authority 3 has put it : " The clinical 

 diagnosis of tuberculosis even by the most expert clinical 

 examiner, except in advanced cases, is always unreliable, as 



1 Zeitschriftfur Infektionskrarikheiten der Haustiere, 1905. 



2 Ibid., 1908, vol. Ix. p. 410. 

 3 McEachran, Trans. British Congress on Tuberculosis, 1901, vol. iv. p. 111. 



