Emphysematous cystitis: a review of 36 dogs and cats

Emphysematous cystitis (EC) is a rare form of complicated urinary tract infection, with characteristic features being gas within the bladder wall and lumen. The clinical manifestations are various and not always associated with symptoms of lower urinary tract. The literature indicates that it is often associated with diabetes mellitus or other predisposing pathologies [1]. Imaging methods, such the radiology or ultrasonography are pivotal for obtening a definitive diagnosis of EC [2]. The aim of this study was to describe common traits of dogs and cats with EC and compare them with literature. We retrospectively evaluated subjects with diagnosis of emphysematous cystitis enrolled from 2010 to 2016. Only patients with full clinical records, blood test and urine screening were considered. For any subject, the symptoms, the pre-subsidiary cause and the ethiological cause has been established. We evaluated with ultrasonography the stratigraphy of the bladder wall, the appearance of the contents (corpuscolate or anechoic), and the localization of air (bladder wall, lumen or both). We found 38 patients (36 dogs and 2 cats), 17 males and 21 females, aged from 5 months to 14 years (mean age: 9 years). The clinical signs were highly variable. Gross hematuria and other symptoms of cystitis (dysuria, pollachiuria) are most common (23/38). Fever, anorexia, vomiting and abdominal pain occurring in 9 subjects, while 6/38 were asymptomatic. Diabetes afflicted only 15,7% of the patients and the most common predisposing factor was recurring urinary tract infection (42%), while 18,4% of patients showed urinary stasis from neurogenic bladdder dysfunction; 24% were other causes already reported in the bibliography. The urinalyses presented glicosuria in three dogs, including 2 non-diabetic. Escherichia coli (55%) and Klebsiella pneumoniae (13%) were the two major organism isolated in urine cultures. In a few cases we isolated Proteus mirabilis, Enterococcus faecalis and Klesbiella Pneumoniae. Three cultures were negative. The ultrasound showed wall irregularly thickened in 20 subjects with 6/38 with polypoid cystitis; widespread intramural echogenic foci exhibiting dirty acoustic shadowing and a reverberation artifact consistent with gas were seen in 18 patients. Intraluminal gas was seen in 10 patients; the intraluminal foci were mobile and shifted to a nondependent location with postural changes. Ten dogs presented gas both in the bladder wall and in the bladder lumen. Only 5 dogs had radiological study: 4/5 confirmed the EC. In our review there is not difference with veterinary literature for age, sex and clinical symtoms; the predisponding risk factors are different: the number of diabetic cases is considerably less than that other authors (50%). The results of urine cultures in EC patients with no gas producing organism, such as Enterococcus, suggest the possibility of mixed infections. With respect to blood analyses there are not specific data suggesting the presence of EC. The use of ultrasound is pivotal for obtaining a definitive diagnosis of EC; ultrasonography seems to be more sensitive than radiography at early stage of the disease and can detect the presence of air in other structures [2]; one dog showed gas in renal pelvis and one in the prostate gland.