It consists of more or less acute inflammation of the vesical mucous membrane. The inflammation sometimes extends to the muscular coat and the peri-vesical tissues, setting up local or general peritonitis.
Causation. The internal causes to which Cruzel attributes the disease are rather open to question. Retention of urine in particular is common in working oxen, which only pass urine when resting, and this would be more likely to produce distention, paralysis, or rupture of the bladder than true inflammation; it is doubtful whether inflammation would even follow the chronic irritation resulting from frequently repeated over-distention.
The ingestion of irritant plants certainly has a more marked action. Irritant principles eliminated by the kidneys might not injure them, although they would bring about changes in the vesical mucous membrane, with which they would remain in contact for some time.
More frequently cystitis is the result of inflammation due to continuity of tissue, and forms a complication of urethritis, vaginitis, and the conditions set up by retention of the after-birth. It may also result from ascending infection causing pyelo-nephritis, or ascending infection of any kind which eventually attacks the bladder. It is a very common consequence of the use of unclean catheters, but only in equines and females, as the catheter is not passed in the ox or bull until after urethrotomy.
In by far the majority of cases it is of infectious, and not of toxic, origin.
Symptoms. At first the symptoms are obscure. They commence with slight colic, and are afterwards characterised by frequent, difficult and painful micturition and by the small quantity of urine passed on each occasion.
The urine, moreover, is modified in appearance. At first it contains a small quantity of blood, and is reddish, or at least of a darker tint than is usual. Later it becomes thick and whitish, and contains greyish films of epithelium, and the débris of fibrinous coagula. The microscope reveals in it the presence of pus corpuscles, flat polygonal cells with large nuclei, and sometimes red blood corpuscles.
Locally almost all that can be detected in male animals is a little tenderness of the neck of the bladder on rectal examination, and in females on examination of the meatus urinarius by means of a speculum.
The vaginal mucous membrane then appears inflamed around the meatus, which itself is exceedingly sensitive.
In cases of very marked inflammation, accompanied by partial necrosis of the mucous membrane or the production of false membranes, the temperature rises as high as 104° Fahr. (40° C.), appetite disappears, colic is extremely acute, and violent efforts to pass urine are continually made until the animal is completely exhausted. The patient then refuses to walk about, but frequently lies down, arches its back, and constantly makes efforts to urinate, which are abortive or end only in the passage of little jets of fluid.