524 DISEASES OF THE BLADDER. 



shades between a pale pink and a bright arterial red colour may be 

 observed. 



The patients sometimes seem to pass unaltered blood in the 

 urine, but on microscopic examination this blood is found to be 

 extremely diluted. Provided the bladder is not gravely infected by 

 the (secondary) penetration of germs into its cavity the blood cor- 

 puscles remain normal, or are scarcely changed. As soon as the 

 bladder, however, becomes secondarily infected an almost immediate 

 change takes place ; the red blood corpuscles become crenated, 

 broken up and dissociated ; the haemoglobin is also partly dissolved 

 and modified, and at this stage the urine is red-brown or coffee- 

 coloured, according to the length of time it has been retained in the 

 bladder. 



In other cases, chiefly when haematuria has existed for some time, 

 the extravasated blood coagulates in the bladder, and the urine passed 

 contains filamentous clots the size of a man's thumb, a pigeon's egg, 

 or more. If the clots formed are too large to be passed, which is 

 often the case in the ox, they may obstruct the urethra, causing 

 retention of urine and all the accidents which accompany this con- 

 dition, even including rupture of the bladder. This, in the ox, is a 

 frequent termination. In the cow the dilatability and shortness of 

 the urethra render retention of urine much rarer. It is certainly 

 possible, however, and it is not exceptional, to find from 4 to 6 lbs. 

 of clotted matter in the distended bladder. All these conditions can 

 be detected by rectal exploration, and by attention to the symptoms 

 of obstruction of the urethra. 



Whenever there is retention of clots dysuria is extremely marked 

 and, so to speak, permanent, the animals having continual tenesmus. 



Haematuria observes a slow, progressive course, which, in time, ends 

 in death by exhaustion, though this is not invariably the case. Haema- 

 turia is frequentl}^ intermittent, and, after having been very marked for 

 weeks or months, may suddenly or gradually cease, and only reappear 

 a long time afterwards. This fact is explained by a study of the de- 

 velopment of the lesions. When ulceration occurs the sub-epithelial 

 vessels of the mucous membrane, which have contributed to the forma- 

 tion of the haemorrhagic spot, are widely open, and a capillary haemor- 

 rhage results ; but as soon as a small clot forms in this position, or local 

 capillary thrombosis occurs, the haemorrhage ceases, with the result that 

 the haematuria disappears. Unfortunately, however, the obliterating 

 clots are not permanent, any more than the local thrombosis — or, in 

 the event of their proving permanent, another small lesion develops at a 

 different point, and this lesion may at any time cause the reappear- 

 ance of the haematuria; the process goes on until the animal succumbs. 



