Postobstructive diuresis in cats with naturally occurring lower urinary tract obstruction: incidence, severity and association with laboratory parameters on admission

Blood plasma and urinary biomarkers of oxidative stress in cats with urethral obstruction

BACKGROUND

This study aimed to investigate variations of the oxidative status in cats affected by urethral obstruction (UO) under Feline Idiopathic Cystitis (FIC) and Bacterial Cystitis (BC), in comparison with a group of healthy subjects. In both groups, the levels of several markers (either direct or indirect) indicative of the oxidative attack and of the antioxidant response were analyzed on plasma and urine samples. In particular, the plasma samples were evaluated for nitric oxide (NO), hydroperoxides derived by reactive oxygen activity (d-ROMs test), superoxide anion (O2-), glutathione peroxidase activity (GPx), superoxide dismutase activity (SOD), and ferric reducing antioxidant power (FRAP test); while on urine the levels of NO, d-ROMs, FRAP, SOD, malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) were measured. Urine of UO patients was also subjected to urine-culture test.

RESULTS

The analytical data on plasma showed that UO, independently of the FIC or BC etiology, induced the insurgence of oxidative stress conditions at the systemic level. In the urine of the UO patients, except for SOD that increased, the markers of redox status were markedly decreased due probably their compromised filtration, thus suggesting involvement of renal function (assessed also by the high levels of plasma creatinine and proteinuria) with no oxidative damage of the lower urinary tract. Moreover, the adoption of a novel oxidative stress index' (OSI) allowed to establish, by means of a numerical value, the different degrees of oxidative stress conditions for single UO patients, both in terms of oxidative attack and antioxidant response.

CONCLUSIONS

Feline urethral obstruction, induced by Idiopathic Cystitis and Bacterial Cystitis, causes oxidative stress conditions at the systemic level that do not interest the lower urinary tract. Despite to the high variability of the profiles of oxidative stress indexes both in healthy and UO patients, the determination of OSI made possible the evaluation of their single degrees of oxidative stress. Possibly the results of this investigation can be compared with those of correspondent pathologies both in humans and in other animal species.

Neutering is not associated with early-onset urethral obstruction in cats

OBJECTIVES

The purpose of this study was to evaluate the correlation between clinical aspects and urethral lesions with reproductive status and age at neutering in obstructed male cats.

METHODS

All cats with compatible signs of urethral obstruction (UO) treated at the Veterinary Hospital of the Federal Rural University of Pernambuco from 2019 to 2021 were divided into three groups according to their reproductive status: intact; prepubertal neutered; and post-pubertal neutered. Cats with compatible signs of UO were selected for further analysis. Age, clinical signs, age at neutering and age of the first obstructive event were documented. Cats with recurrent obstructive urinary signs or urethral trauma that made catheterization impossible were referred for perineal urethrostomy. The morphology of the excised penises was assessed by histopathological analysis.

RESULTS

Of 84 cats with signs of UO included in this study, 28.6% were classified as intact, 28.6% as prepubertal neutered and 42.8% as post-pubertal neutered. Intact cats had a significantly earlier onset of UO compared with prepubertal and post-pubertal neutered cats, as seen by the age at obstruction (3.6 vs 5.7 and 5.5 years, respectively). Similar clinical signs and histopathological lesions were observed in all groups. The main clinical signs observed were stranguria, hematuria and pollakiuria. All cats had some degree of injury in the penile urethra. The most common lesions were hemorrhage, fibrosis and congestion.

CONCLUSIONS AND RELEVANCE

It appears that intact cats had an earlier onset of UO than neutered cats, regardless of age at neutering. Urethral histopathological lesions and clinical signs were similar in both groups. Pediatric neutering represents a useful tool in the control of abandoned and stray animals and the consequent dissemination of zoonoses, thus having a positive impact on public health.

Presentation Variables Associated With the Development of Severe Post-obstructive Diuresis in Male Cats Following Relief of Urethral Obstruction

Background

Diuresis following relief of urethral obstruction is a potentially life-threatening complication of feline urethral obstruction. Evidence regarding the incidence of post-obstructive diuresis (POD) in cats is scarce. Establishing historical, physical examination, and initial clinicopathologic variables associated with risk for developing POD may better enable clinicians to direct treatment for this common feline emergency and to educate clients regarding financial expectations.

Objectives

To report the incidence of POD in a large group of cats with urethral obstruction and determine whether select presenting physical examination or initial clinicopathologic variables may predict the onset or severity of POD.

Methods

The records of 260 cats that were admitted to the University of California, Davis, Veterinary Medical Teaching Hospital for urethral obstruction were reviewed. Urine output after urethral catherization was categorized into no POD (urine output ≤ 2 mL/kg/h), mild-moderate POD (urine output > 2 but <5 mL/kg/h) and severe POD (urine output ≥ 5 mL/kg/h). Select presentation physical examination, venous acid-base, electrolyte, serum biochemistry, and urinalysis results were compared among the groups.

Results

67.7% of cats experienced POD, and in 35% of cats it was categorized as severe. Evaluated historical and physical examination variables correlated with development of POD were lower body weight and, for severe POD, hypovolemia. Clinicopathologic variables associated with development of POD included acidemia, azotemia, hyperphosphatemia, hyperkalemia, hyponatremia, hypochloremia, hypocalcemia, hypermagnesemia, and hypoalbuminemia. Cats with severe POD were hospitalized a median of 1 day longer than those without POD.

Conclusions

Results of the present study indicate that there are presentation variables associated with onset and severity of POD following relief of feline urethral obstruction.

Factors associated with postobstructive diuresis following decompressive surgery with placement of ureteral stents or subcutaneous ureteral bypass systems for treatment of ureteral obstruction in cats: 37 cases (2010-2014)

OBJECTIVE

To describe postobstructive diuresis (POD) in cats undergoing surgical placement of ureteral stents or subcutaneous ureteral bypass systems for treatment of ureteral obstruction in cats and to identify factors associated with duration and maximum severity of POD.

DESIGN

Retrospective case series.

ANIMALS

37 client-owned cats with ureteral obstruction treated between August 2010 and December 2014.

PROCEDURES

Medical records were reviewed, and data extracted included signalment, history, results from physical examinations and clinical laboratory analyses, treatment, urine output, and outcome. Data were evaluated to identify factors associated with POD duration and maximum severity, alone or in combination.

RESULTS

Serum concentrations of creatinine, potassium, phosphorus, and BUN before surgery positively correlated with duration and maximum severity of POD. Absolute changes in serum concentrations of creatinine, potassium, and BUN from before surgery to after surgery positively correlated with POD duration. Cats with anuria before surgery had longer POD than did other cats; however, there was no difference in POD duration or maximum severity with unilateral versus bilateral ureteral obstruction. Thirty-four of 37 (92%) cats survived to hospital discharge, which was not associated with whether ureteral obstruction was unilateral or bilateral. Azotemia resolved in 17 of the 34 (50%) cats that survived to hospital discharge.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of the present study indicated that several factors were associated with POD duration and maximum severity, alone or in combination, and that with intensive management of fluid and electrolyte derangements, regardless of the extent of the original azotemia, a high percentage of cats survived to hospital discharge.