5o8 THE CONTROL OF THE MILK SUPPL V 



For all these matters play a direct part in the propagation of 

 disease among cattle.^ 



There are three chief methods for detection of disease, such 

 as tuberculosis, in milch cows, namely — (a) clinical inspection, 

 (d) bacteriological examination, and (c) diagnostic inoculations. 



(a) Inspection. — The clinical diagnosis of tuberculosis, even 

 by the most expert clinician, except in advanced cases, is always 

 unreliable, as the disease may exist in such a stage as would be 

 impossible of diagnosis by this means. Still much may be done 

 towards obtaining a diagnosis even on clinical grounds. If the 

 disease affects the respiratory organs there is a frequent cough, 

 disturbance of the respiration, quickened breathing. Dull sounds 

 may be elicited from the lungs. The superficial glands in the 

 throat, between the jaws, under the ear or the udder, may be 

 hard and swollen. If the disease is mostly abdominal the symptoms 

 of defective nutrition are early apparent — emaciation, lessened 

 secretion of milk, indigestion, breathlessness and general failure, 

 more or less rapid. 



Inspection to be of value must be regular, frequent, and 

 thorough, as carried out in Denmark. The moment a sick 

 animal is detected it must be eliminated from the milk herd 

 and isolated by itself Many of the great dairy companies, both 

 in Europe and America, have their own expert veterinary 

 inspectors for the purpose of regularly overhauling the milk 

 herds and examining into the conditions of their stabling, etc. 

 The value of inspection is well shown in the records appertain- 

 ing to Manchester and the London County Council (see p. 212). 



(d) Bacteriologrical examination of the milk yields, of course, 

 a result primarily having relation to the milk alone. But 

 indirectly such examinations may be used as an indication of 

 the condition of the udder, its healthfulness or otherwise, and in 

 this way is some test as to the herd. Nocard and others have 

 recommended as the simplest and surest method of making a 

 diagnosis the use of a trocar for examining any portion of the 

 udder desired.^ By means of this trocar one can extract from 



^ See also La propagation de la Tuberculose (Commission de la Tuberculose), 

 1900, pp. 264-277. 



2 These trocars are 2-3 millimetres in diameter. The point is conical instead 

 of three-sided, thus avoiding the action of the sharp angles of the ordinary trocar 

 that sometimes give rise to slight haemorrhage and tinge the milk with blood for 

 two or three days ; but the conically pointed trocar penetrates the skin with 

 difficulty, so it is necessary to make a small incision with a lancet in the skin 

 through which to pass it into the mammary gland. 



