190 



Liver Disease of Poultry. 



persistent. The comb and wattles are pale and dry, and the 

 mucous membranes are pale, wherever visible. The birds leave 

 off laying soon as a rule. As a result of the extreme emaciation, 

 which is usually the most important and general characteristic, 

 the bones become very prominent, and the effect may be 

 best judged by passing the hand over the keel of the breast 

 bone. 



Anatomical Symptoms. 



On opening the bird the owner will find that the external 

 appearances of thinness of the muscles are borne out by taking 

 off the skin. The muscles are pale in colour, thus adding 

 further testimony to the symptoms already noted of anaemia, 

 but the most important and characteristic appearances are seen 

 in the body cavity. The liver is brown in colour, sticky to the 

 touch, and dotted all over with small white spots, or larger spots 

 or patches of a white grey or yellow colour. Lifting up the 

 gizzard the spleen is almost certain to be found to be affected. 

 It is usually enlarged and beset with small or large tubercles, 

 which frequently project as fat-like tumours from its surface. 

 The intestine and the lymphatic glands of the mesenteries are 

 also often the seats of similar deposits. Tubercles sometimes 

 occur in the skin and the joints, and the local swellings may 

 then be seen externally, and affect the movements of the bird. 

 The other organs of the body, as a rule, are not affected. As 

 a result of the weakness produced by the disease the poultry 

 are more liable to parasitic invasion, and nematode or round 

 worms may be got, for example, in nearly every case, at the 

 blind ends of the caeca. 



Cause. 



In 1883 Dr. Heneage Gibbes reported on specimens sent to 

 him by Dr. J. Bland Sutton that the tubercles contained bacilli 

 which were indistinguishable from those of tuberculosis. The 

 truth of these observations has since been confirmed by 

 investigations made at home and abroad. 



The exciting cause of the disease, then, is a bacillus which 

 may be considered a variety of the bacillus of mammalian tuber- 

 culosis. It gains entrance in practically every case with the 



