The urine passed contains little greyish necrotic fragments or débris of false membranes, suggestive of diphtheria. In female animals the canal of the urethra may also become obstructed, and rupture of the bladder, though rare, occasionally occurs.
In the ordinary forms inflammation persists for two to three weeks, then diminishes in intensity, and either ends in recovery or becomes chronic.
In the grave forms, where inflammation and infection extend to the peri-vesical tissues and the peritoneum, death by peritonitis is the rule.
On post-mortem examination, the mucous membrane is seen to be of a greyish colour, and sloughing or gangrenous over surfaces of varying size, whilst the surroundings are infiltrated, blackish and greatly thickened. The whole of the connective tissue layer which supports the peritoneum near the base of the bladder, and also the adipose tissue around the bladder, are markedly inflamed. At this stage pelvi-peritonitis or generalised peritonitis may occur as complications.
In the simple forms the mucous membrane is desquamating, infiltrated, and covered with granulations of apparent healthy appearance.
Diagnosis. The diagnosis is comparatively easy, the external symptoms being so clearly defined. There is a difficulty, however, in distinguishing this disease from cystitis caused by a calculus. In male animals this latter form of cystitis is characterised by frequent spasmodic contractions of the accelerator urinæ. In acute cystitis, on the contrary, the contractions are temporary only and of no importance. Lastly, in female animals cystitis due to calculus formation is quite exceptional, owing to the large diameter and shortness of the urethra.
When nephritis and cystitis co-exist certain signs indicate the fact.
Prognosis. The prognosis varies, according to the acuteness of the disease and the character of the urine and epithelial débris, which afford valuable information.
Treatment. The treatment should be directed towards relieving the vesical and pelvic pain and modifying the local conditions.
Hot fomentations to the loins and flanks relieve pain. The administration of bicarbonate of soda and of cold drinks, such as barley-water, decoctions of couch grass and pellitory, mucilage, etc., are of service. These materials are readily taken by the patients, and have a soothing effect. Camphor also produces good results, but benzoate of soda is most useful on account of the disinfectant action produced within the bladder, as a consequence of the benzoic acid being separately eliminated by the kidney. Repeated washing out of the bladder with antiseptic solutions has been recommended, but is open to criticism. Such treatment is difficult in male animals, owing to the special formation of the glans penis and urethra, and in female animals it is by no means easy. In all cases of acute cystitis, in fact, the passage of the catheter is painful, and as a metal, gutta-percha or hard rubber sound is used, the mere contact of the tip of the instrument injures the diseased mucous membrane, makes it bleed, and gives rise to danger of autoinoculation, with the possibility of serious results.