Feline lower urinary tract disease is a complex set of clinical signs that most commonly occurs in indoor male cats.1–3 Cats with FLUTD often have stranguria, pollakiuria, periuria (inappropriate urination), hematuria, lethargy, vomiting, signs of abdominal pain, and vocalization. Urethral obstruction is a complication of FLUTD that can lead to postrenal azotemia and severe metabolic abnormalities.4–6 Hyperkalemia is the most life-threatening derangement, resulting in altered cardiac conduction and bradyarrhythmias. Urolithiasis, urethral plugs, crystalluria, urinary tract infection, and interstitial cystitis have been identified as possible inciting causes for urethral obstruction.1–3,7,8 Medical treatment for urethral obstruction may include IV administration of fluids, relief of the obstruction, and placement of an indwelling urinary catheter. The cost and duration of hospitalization for cats with urethral obstruction typically depend on the severity of illness, clinician preference, and availability of 24-hour care. The prognosis for survival to discharge is excellent,4,9,10 but recurrent urethral obstruction is a frustration for owners that can lead to euthanasia rather than continued medical or surgical treatment.
The associated risk factors and prognosis for recurrent urethral obstruction were recently evaluated retrospectively at a university hospital.9 Recurrent urethral obstruction was identified in 22% of cats within 6 months and 24% within 2 years. Another study10 identified recurrent obstruction in 36% of cats, most within 2 weeks after discharge.
The purpose of the study reported here was to evaluate signalment and laboratory abnormalities as risk factors for recurrent obstruction in cats treated medically because of urethral obstruction. Additionally, we sought to identify associations between specific treatment decisions and discharge recommendations to owners and the risk of recurrent urethral obstruction within 30 days after hospital discharge. Recurrent urethral obstruction was defined as a nonexpressible bladder or nonproductive stranguria documented by a veterinarian within the designated time period.
Materials and Methods
This prospective case series was undertaken in 3 private small-animal emergency hospitals. Male cats examined in the emergency departments of these hospitals because of acute urethral obstruction between April 1, 2010, and April 30, 2011, were eligible for inclusion. Urethral obstruction was defined as a firm, nonexpressible bladder on physical examination, with or without a history of signs of FLUTD, or nonproductive stranguria. Cats that had been evaluated or treated by a referring veterinarian were included, unless an indwelling urinary catheter was placed prior to arrival at the participating hospital. Further exclusion criteria included catheterization for < 1 hour, death or euthanasia prior to urethral catheter placement, and incomplete medical records. All cats treated surgically (perineal urethrostomy, cystotomy, or both) during the initial hospitalization period were excluded from the study population.
All cats were treated according to the attending veterinarian's discretion. After discharge from the hospital, the medical records were reviewed for physical examination findings, age, weight, neuter status, laboratory abnormalities, and specific medical treatments.
Prior to initiation of IV fluid administration, a venous blood sample was collected in a heparinized syringe for measurement of the following parametersa: pH; Pco2; and bicarbonate, sodium, potassium, chloride, glucose, lactate, ionized calcium, BUN, and creatinine concentrations. Packed cell volume was determined after centrifugation, and total solids concentration was measured by means of refractometry. Cats were assigned to a category of critical illness if they met any 2 of the 4 following criteria: rectal temperature < 37.8°C (100°F), heart rate < 140 beats/min, serum potassium concentration > 8.0 mmol/L, or blood pH < 7.2.
Each cat was sedated at the discretion of the attending clinician to facilitate relief of the obstruction and placement of an indwelling urinary catheter. Briefly, the preputial area was clipped of fur and the skin was gently scrubbed with chlorhexidine gluconate solution.b A 3.5F polypropylene catheterc was advanced into the urethra to relieve the obstruction. If resistance was met, the catheter was attached to a saline (0.9% NaCl) solution–filled syringe and pulsatile pressure was applied. For more difficult obstructions, a stainless steel olive-tipped catheterd was used to clear the obstruction. Clinicians were asked to subjectively grade the catheterization as easy or difficult. Once the obstruction was cleared, a red rubber cathetere was advanced into the bladder. Depending on clinician preference, the bladder was actively emptied or lavaged with sterile saline solution. Prior to lavage with saline solution, a urine sample was collected via the catheter into an empty syringe then transferred to an additive-free glass tube. The indwelling urinary catheter was secured to the patient and connected to a closed-collection system. Catheter placement was confirmed with a survey right lateral abdominal radiograph. Urine sediment evaluation was performed in-house within 1 hour after urine sample collection or the urine sample was refrigerated at 4°C until transfer to an outside laboratoryf within 12 hours after collection.
All clinical decisions for medical treatment and monitoring of each patient were at the discretion of the attending veterinarian. Cats were treated with IV fluids prior to or during sedation at the clinician's discretion. The decision to administer an initial fluid bolus, the type of fluids administered, and the dose of fluids administered were determined by the attending veterinarian. All cats were housed in the intensive care unit and were fitted with an Elizabethan collarg to prevent damage to or accidental dislodgement of the urinary catheter. Treatment with antispasmodics and analgesics were initiated after urinary catheter placement at the clinician's discretion. Urine production was recorded every 4 hours. Fresh water and food was available for all cats for the duration of the hospital stay. The indwelling urinary catheter was removed after resolution of hematuria or resolution or stabilization of azotemia (if present), or after 24 hours had passed. The decision to remove the catheter and whether to continue IV fluid administration after urinary catheter removal was at the discretion of the attending veterinarian, but the specific reasons for each cat were not routinely recorded in the medical record. Cats were observed for spontaneous urination for 8 to 12 hours after removal of the urinary catheter. Recurrent obstruction in the hospital was defined as nonproductive stranguria or a nonexpressible bladder during this observation period.
After discharge from the hospital, medical records were reviewed for duration of catheterization, volume of IV fluids administered, duration of hospitalization, and incidence of recurrent urethral obstruction during hospitalization (prior to discharge). Prior to completion of the study period, all radiographs were reviewed by a board-certified radiologist (JOB), who was blinded to the short-term outcome for each cat. Follow-up surveysh were conducted with owners by telephone or via email 30 days after discharge from the hospital. Survey questions included the following: any changes to the cat's diet or environment, medications successfully administered at home, further evaluation by a veterinarian, and incidence of recurrent urethral obstruction.
Statistical analysis—For categorical variables, proportions were reported as percentages. For continuous variables, mean, SD, median, and range were calculated. The primary analyses involved comparison of the distribution of study variables by recurrent urethral obstruction status (yes vs no). The Fisher exact test was used to compare the distribution of categorical variables between the 2 possible outcomes. A logistic regression model was fit for each continuous study variable to predict the probability of recurrent urethral obstruction status. Because of limitations of the analytic sample and the observational nature of the study, it was not possible to fit multivariable logistic regressions models to account for possible confounders. No adjustment for multiple comparisons was undertaken. All analyses were performed with statistical software.i
Results
Study population—One hundred eleven cats were examined for urethral obstruction during the study period. Eleven cats were excluded because of incomplete medical records, death or euthanasia prior to urethral catheterization, catheterization prior to referral, or catheterization for < 1 hour. Seventeen cats were treated surgically (perineal urethrostomy, cystotomy, or both) during their initial hospitalization and were excluded from further analysis. The 83 remaining cats met the criteria for inclusion in the study. Of these 83 cats, 68 had complete follow-up information available. Recurrent urethral obstruction was reported in 10 of the 68 cats.
Signalment and physical examination findings— Cats included in the study consisted of 66 domestic shorthair, 10 domestic longhair, 2 Maine Coon, 2 Siamese, and 1 each of Exotic Shorthair, Himalayan, and Russian Blue. Purebred cats were significantly (P = 0.02) less likely to have recurrent urethral obstruction, compared with the likelihood for mixed-breed cats. One cat was a sexually intact male, and the remaining cats were castrated. The median age was 4.3 years (range, 0.5 to 15 years). There was a significant (P = 0.01) association between increasing age and the risk of recurrent urethral obstruction (median, 8.2 years [range, 2.1 to 1.4 years] vs median, 4 years [range, 0.5 to 15 years]; Table 1). The median body weight was 5.9 kg (13 lb; range, 2.8 to 9.1 kg [6.2 to 20 lb]). Body weight was not significantly (P = 0.72) associated with recurrent urethral obstruction.
Signalment, diagnostic test results, and treatment variables for cats that did (n = 10) or did not (58) have recurrent urethral obstruction in the 30 days following hospital discharge in a study of cats with urethral obstruction treated medically.
Recurrent obstruction | No recurrent obstruction | ||||
---|---|---|---|---|---|
Variable | Mean ± SD | Median (range) | Mean ± SD | Median (range) | P value |
Age (y) | 7.8 ± 3.5 | 8.2 (2.1–14) | 4.8 ± 2.9 | 4 (0.5–15) | 0.01* |
Weight (kg) | 6.0 ± 1.8 | 5.6 (3.6–9.1) | 6.1 ± 1.2 | 6.1 (2.8–8.9) | 0.72 |
Urine pH† | 6.8 ± 0.61 | 7 (6–7.5) | 6.9 ± 0.66 | 7 (5–8.5) | 0.59 |
USG† | 1.036 ± 0.005 | 1.038 (1.029–1.041) | 1.034 ± 0.01 | 1.034 (1.015–1.052) | 0.49 |
Duration of catheterization (h) | 21.6 ± 15.2 | 24 (1–54) | 32.1 ± 14.2 | 26.5 (12–92) | 0.03* |
Duration of hospitalization (h) | 37.4 ± 29.9 | 32 (2–96) | 46.1 ± 17.6 | 42 (14–98) | 0.2 |
IV fluids administered before catheter removal (mL/kg) | 130 ± 90 | 140 (18–325) | 175 ± 150 | 142 (0–1,077) | 0.33 |
Total IV fluids administered (mL/kg) | 165 ± 105 | 199 (18–325) | 198 ± 166 | 163 (0–1,217) | 0.54 |
Value is significantly (P < 0.05) different between cats with recurrent obstruction and those without recurrent obstruction in the follow-up period.
Diagnostic test results were available for 6 cats that had a recurrent obstruction and 46 cats that did not.
Laboratory test results—Results of laboratory testing performed at the time of initial examination were summarized (Table 2). Thirty-two cats had moderate to severe azotemia (BUN concentration > 40 mg/dL; creatinine concentration > 2.5 mg/dL). There was no significant (P = 0.99) association between the degree of azotemia and the risk of recurrent urethral obstruction. Median potassium concentration for all cats was 3.8 mmol/L (range, 2.78 to 9.5 mmol/L). Hyperkalemia was identified in 22 of 82 cats; severe hyperkalemia (> 8 mmol/L) occurred in 4 of those cats. Ten cats met the specified criteria for critical illness. In these cats, the median venous blood pH was 7.21 (range, 7.15 to 7.38), and the median potassium concentration was 6.14 mmol/L (range, 3.39 to 9.5 mmol/L). There was no significant (P = 0.99) association between the incidence of critical illness and the risk of recurrent urethral obstruction.
Selected results of diagnostic testing performed at the time of hospital admission for 83 cats with urethral obstruction.
Variable | No. of cats | Mean ± SD | Median (range) | Reference range |
---|---|---|---|---|
Venous pH | 81 | 7.34 ± 0.06 | 7.35 (7.15–7.44) | 7.30–7.40 |
BUN (g/dL) | 80 | 63.2 ± 50.4 | 33.5 (17–150) | 15–32 |
Creatinine (g/dL) | 75 | 3.16 ± 3.6 | 1.3 (0.7–18.5) | 0.6–1.3 |
Glucose (mg/dL) | 80 | 163.7 ± 47.6 | 161.5 (65–295) | 67–168 |
Ionized calcium (mmol/L) | 82 | 1.03 ± 0.12 | 1.03 (0.68–1.24) | 1.10–1.22 |
Lactate (mmol/L) | 81 | 2.0 ± 1.05 | 1.7 (0.5–4.5) | 1.0–2.0 |
Potassium (mmol/L) | 82 | 4.35 ± 1.38 | 3.8 (2.78–9.5) | 3.6–4.6 |
PCV (%) | 80 | 43.7 ± 6.1 | 44 (26–55) | 30–55 |
Total solids (g/dL) | 80 | 7.07 ± 0.89 | 7 (4.7–10) | 5.5–7.5 |
Overall, 81 urine samples were evaluated in-house or at an outside laboratory.f Crystalluria was identified in 69 samples. The presence of urinary crystals was not significantly (P = 0.99) associated with the risk of recurrent urethral obstruction. Neither USG (P = 0.49) nor urine pH (P = 0.59) was significantly associated with the risk of recurrent urethral obstruction (Table 1).
Radiographic evaluation—Plain radiography was performed on 34 of 83 cats after placement of a urinary catheter. Abnormalities included caudal abdominal effusion in 10 cats, material other than calculi in the bladder in 5 cats, and cystic calculi in 1 cat. None of the radiographic abnormalities were associated with the risk of recurrent urethral obstruction.
Treatment—Following admission, all cats were sedated or anesthetized with a protocol as decided by the clinician for relief of the urethral obstruction and placement of an indwelling urinary catheter. Catheterization with a smaller catheter (3.5 vs 5F) was not significantly (P = 0.99) associated with the risk of recurrent urethral obstruction. The subjective difficulty of the catheterization attempt (easy vs difficult) was not significantly (P = 0.75) associated with the risk of recurrent urethral obstruction.
Intravenous fluid volumes delivered prior to urinary catheter removal and total IV fluid volume administrered during hospitalization were estimated for each cat (Table 1). There was no significant (P = 0.33) association between the volume of IV fluids delivered prior to catheter removal and the risk of recurrent urethral obstruction. Continuation of IV fluid administration after removal of the urinary catheter was not correlated (P = 0.99) with the risk of recurrent urethral obstruction.
Durations of catheterization and hospitalization were summarized (Table 1). A shorter duration of catheterization was significantly (P = 0.03) associated with a higher probability of recurrent obstruction in the follow-up period (median, 24.5 hours [range, 1 to 54 hours] vs median, 26.5 hours [range, 12 to 92 hours]; Figure 1). The duration of hospitalization was not significantly (P = 0.2) different between the 2 groups (median, 42 hours [range, 14 to 98 hours] vs median, 32 hours [range, 2 to 96 hours]; Figure 2).
Follow-up survey—Of the 68 cats for which the follow-up survey was completed, median time to follow-up after hospital discharge was 41 days (range, 25 to 110 days). Medications administered after discharge included urethral antispasmodics (prazosinj or phenoxy-benzaminek) in 61 of 68 cats, analgesics (sublingual buprenorphinel) in 50 of 68 cats, and antimicrobials (amoxicillinm or amoxicillin trihydrate–clavulanate potassiumn) in 21 of 68 cats. Administration of medication of any kind was not significantly associated with the risk of recurrent urethral obstruction.
The type of diet fed after hospital discharge was recorded in 59 cats. Of the 50 owners who changed to a prescription diet, 9 fed dry food only, 12 fed canned food only, and 29 fed a mixture of canned and dry foods. Neither feeding a prescription diet (P = 0.34) nor feeding solely canned food of any brand (P = 0.99) was associated with the risk of recurrent urethral obstruction.
Overall, 47 of 68 owners made changes to their cat's environment at home. Litter changes were reported for 33 of 68 cats, including increasing the number of litter boxes, cleaning the litter more frequently, and changing the type of litter. Husbandry changes were reported for 24 of 68 cats, including spending more time with the cat, keeping the cat separate from other animals in the house, and keeping the cat indoors. Alterations to the cat's water access were reported in 34 of 68 cats, including increasing the number of water bowls, adding a water fountain, allowing the cat to drink from the sink, adding water to the food, and adding flavoring to the water. Analysis of a combined measure of environmental modifications (any change in litter, change in husbandry, or increased water availability) was significantly (P = 0.007) associated with a lower risk of recurrent urethral obstruction. When each type of environment change was analyzed separately, however, only increasing water availability was significantly (P < 0.001) associated with a lower risk of recurrent urethral obstruction during the follow-up period.
Short-term outcome—Feline lower urinary tract disease signs that continued immediately after discharge were reported in 50 of the 68 cats for which surveys were completed. The most commonly reported ongoing signs of FLUTD after discharge were pollakiuria (25/50), stranguria (23/50), and periuria (12/50). Duration of clinical signs ranged from 2 days to > 30 days after discharge. Twenty-nine of 68 owners reported signs of FLUTD that lasted ≥ 7 days. Among the 68 cats with follow-up information, 21 were further evaluated by a veterinarian within 30 days after hospital discharge. Eleven cats were treated on an outpatient basis for signs of FLUTD, and 10 were confirmed to have recurrent urethral obstruction. Of the 10 cats with recurrent urethral obstruction, 2 were euthanized because of their disease and 8 were treated surgically. One cat was treated repeatedly after initial discharge from the hospital and was eventually euthanized because of recurrent FLUTD episodes (but not recurrent urethral obstruction) within 30 days after discharge from the hospital. Of the 68 cats with follow-up information, 65 survived to 30 days after discharge from the hospital.
Discussion
The present study evaluated male cats examined for urethral obstruction at 3 hospitals over a 13-month period. Results suggested that a longer duration of catheterization may decrease the risk of short-term recurrent urethral obstruction in cats treated medically. Older cats (8.2 vs 4 years) may be at higher risk for recurrent urethral obstruction. Owners should be encouraged to increase water availability after discharge in cats treated for urethral obstruction to decrease the likelihood of recurrent obstruction.
Fifteen percent (10/68) of cats in the present study developed short-term recurrent urethral obstruction over a 1-month follow-up period. Previous studies9–11 have reported recurrence rates of 22% to 50%. Two such studies were conducted retrospectively in Israel9 and Switzerland,10 and the higher recurrence rates may reflect differences in urethral obstruction etiology, climate, husbandry, and diet.2,3,8 Additionally, each of these studies had variable follow-up periods (2 to 4 years9 and 5 to 827 days10), which may explain the higher rates of recurrence.
Epidemiological studies in male cats have shown differing influences of age and breed on the risks of developing FLUTD and urethral obstruction. In the present study, older cats (median age, 8.2 vs 4 years) were more likely to have short-term recurrent urethral obstruction. Previous studies have suggested that cats older than 4 years of age are at lower risk for recurrent urethral obstruction11 or that age is not a significant risk factor for recurrence.10 Similarly, the impact of breed on the risk of urethral obstruction varies among reports.1–3,9 Purebred cats were less likely to have recurrent urethral obstruction in the present study, but there were too few pedigreed cats to evaluate each breed separately. These mixed results regarding the influence of age and breed on recurrent urethral obstruction may be due to small sample sizes or differences in husbandry, available diet types, or etiology of urethral obstruction. Previous studies have shown that urinary tract infection2,8 and urolithiasis2 are more common in older cats, whereas idiopathic FLUTD2 occurs more commonly in younger cats. In the present study, cats with different etiologies were not evaluated separately, which may also confound the significance of age and breed as risk factors for recurrent urethral obstruction.
Catheter type and size have not previously been evaluated with regard to outcome in cats with urethral obstruction. We speculated that cats with narrow urethral openings or severe urethral spasm would have a higher risk of recurrent urethral obstruction. However, in this study, neither the size of urinary catheter nor the relative subjective difficulty of catheter placement was associated with the risk of recurrent urethral obstruction.
Duration of catheterization was associated with short-term outcome in the present study. Although the median duration of catheterization was similar for cats without and with recurrent urethral obstruction (26.5 vs 24.5 hours), there was a significant association with the probability of recurrent urethral obstruction. Further prospective studies may focus on identifying an ideal or maximum duration of catheterization to better clarify the role this variable has on outcome. Possible explanations for the association between the lower risk of recurrent urethral obstruction and longer catheterization time include the resolution of urethral and cystic inflammation, adequate time for antispasmodics to take effect, or resolution of postobstructive diuresis prior to discharge from the hospital. A previous study12 identified that postobstructive diuresis (defined as urine production > 2 mL/kg/h [0.91 mL/lb/h]) was more likely to occur from 18 to > 48 hours after placement of a urinary catheter. The present study did not evaluate the incidence of postobstructive diuresis, but future studies may clarify its influence, if any, on the risk of recurrent urethral obstruction in affected cats.
In the present study, neither the volume of IV fluids delivered nor the continuation of IV fluid administration after removal of the urinary catheter was associated with the risk of recurrent urethral obstruction. In our hospitals, IV fluid rates for cats with urethral obstruction are typically chosen and adjusted on the basis of estimated dehydration at admission, urine output during hospitalization, and insensible losses. The decision to continue fluid administration after catheter removal is dependent on clinician preference. Increased IV fluid delivery is likely to increase urine volume, which could reduce bladder inflammation and the accumulation of crystals, debris, and mucus. It is unclear why the volume of IV fluids administered was unrelated to the risk of recurrent urethral obstruction in the present study. Further studies may address different IV fluid administration strategies to determine whether there is any significant association between IV fluid administration and outcome in cats treated for urethral obstruction.
Bradycardia and hypothermia have been associated with severe illness in cats with urethral obstruction.6 Metabolic acidosis is reportedly common in cats with urethral obstruction and can exacerbate the cardiotoxicity associated with severe hyperkalemia.6 In the present study, cats were assigned to a category of critical illness if they met any 2 of the 4 following criteria: rectal temperature < 37.8°C, heart rate < 140 beats/min, potassium concentration > 8.0 mmol/L, or blood pH < 7.2. These parameters were extrapolated from prior urethral obstruction studies4,6 and the published criteria for sepsis and systemic inflammatory response syndrome in cats,13 but they have not previously been evaluated as predictors of morbidity or death in the specific combinations detailed here. In the present study, there was no association between critical illness and the risk of recurrent urethral obstruction. Cats with critical illness on initial evaluation may be more likely to have severe urethral or bladder wall injury or ischemia owing to a longer duration of obstruction prior to arrival at the hospital. Despite the lack of correlation noted, it is reasonable to speculate that this type of damage would contribute to recurrent urethral obstruction after medical treatment of the obstruction. A definitive association between duration of obstruction, degree of bladder damage, and incidence of recurrent urethral obstruction would likely require cystoscopic examination or histologic evaluation of bladder samples. At this time, there are insufficient data to support the use of critical illness as defined in this study as a valid prognostic indicator of the risk of recurrent obstruction.
Higher USG and lower urine pH at the time of initial examination have previously been associated with an increased risk of recurrent urethral obstruction.9 Concentrated urine is associated with supersaturation of minerals and crystal formation,14,15 which may be related to the development of urethral obstruction in some patients. Cats with acidic or neutral urine on initial examination may have urethral obstruction from causes other than struvite crystalluria, making them less likely to respond to acidifying diets.9,14 In the present study, neither urine pH nor USG was associated with recurrent urethral obstruction. Considering that urine samples were obtained from the catheter during relief of urethral obstruction and may have been unintentionally diluted, use of USG as a predictive risk factor may be inappropriate. Future studies could include a standardized protocol for urine collection to minimize the chances of dilution and contamination.
It has been theorized that stress plays a role in the onset of urethral obstruction.9,16–18 It has also been suggested that indoor environments are monotonous, which may increase stress and risk of obstruction in certain cats.1,16 Environmental enrichment has been recommended to help prevent the recurrence of FLUTD episodes and urethral obstruction in cats.16 In the present study, increasing water availability after discharge was the only environmental change associated with a decreased risk of recurrent urethral obstruction. Modifications to husbandry after discharge may have an impact on longer-term risks of recurrent urethral obstruction and FLUTD episodes in cats that are sensitive to their environment.
In addition to increasing access to fresh water, dietary modification is another way to increase overall water intake at home. Canned and pouched foods contain higher water content than does dry kibble,15 and there are a number of prescription diets available in both canned and dry forms for cats with FLUTD, crystalluria, and urolithiasis. A previous study19 identified a significantly lower risk of nonobstructive idiopathic cystitis episodes in cats fed canned versus dry formulations of the same pH-modifying diet, suggesting that increasing urine volume is more important than urine acidification. Unexpectedly, neither changing to a prescription diet nor feeding a canned food diet of any kind was associated with a lower risk of recurrent urethral obstruction in the present study. It is likely, however, that a longer follow-up period would yield different results by allowing more time for a diet change to affect urine volume or urine pH.
Several limitations were identified in the present study. Although case enrollment was prospective, the study design was observational and treatment decisions were not standardized or controlled. It is generally accepted that FLUTD and urethral obstruction have many etiologies and contributing factors. Attributing outcome to any 1 treatment decision is, at best, an oversimplification of a complex disease, especially when evaluated without study controls. The strength in our study design was that sequential enrollment of cases allowed the primary investigator to contact owners in a timely manner, which may have prevented recall bias regarding the details of short-term outcome.
Previous studies9,10 have not identified a difference in recurrence rates among groups of cats with uroliths, urethral plugs, and idiopathic urethral obstruction. A known limitation of the present study was that a comprehensive diagnostic evaluation was not completed in every cat. For this reason, the risk of short-term recurrent urethral obstruction was not evaluated with regard to etiology. Furthermore, even in patients that undergo a comprehensive diagnostic evaluation, a definitive diagnosis is not always identified in cats with urethral obstruction. Although this is a limitation of any study evaluating FLUTD and urethral obstruction in cats, future studies may focus on treatment decisions in cats classified according to etiology of urethral obstruction with regard to the risk of recurrent urethral obstruction.
A third limitation of the present study was the exclusion of cats that were briefly catheterized solely to relieve the obstruction without further hospitalization. Comparing the risk of recurrent urethral obstruction in cats treated with this method with that in cats treated with indwelling urinary catheterization and hospitalization may be of value, especially for veterinarians without access to 24-hour facilities. Additionally, given that our results suggested that longer duration of catheterization may reduce the risk of short-term recurrent urethral obstruction, future studies may focus on a possible correlation between longer catheterization times and the risk of urinary tract infection. Obtaining a urine sample for bacterial culture at the time of discharge or in cats that have recurrent urethral obstruction or episodes of FLUTD may provide valuable information regarding the role of urinary tract infection during hospitalization and after discharge.
Finally, small sample size is a known limitation of the present study. Additionally, the reported recurrence rate of 15% may not represent the true incidence of recurrent urethral obstruction because 15 of the initial 83 cats were lost to follow-up. Because of the large number of study variables being considered, some of the significant findings may be due to chance. Possible confounders of the relationships between age, treatment decisions, and environmental changes and recurrence may be included in future studies to make more definitive causal statements.
The purpose of this study was to clarify the influence of signalment and laboratory abnormalities, along with treatment decisions and recommendations made by veterinarians, on the risk of recurrent urethral obstruction. On the basis of the results of the present study, information available at the time of emergency evaluation (eg, age and breed) may be reliable prognostic indicators for the risk of recurrence. Additionally, based on the decreased risk of recurrent obstruction, veterinarians may recommend longer courses of catheterization and increased water intake at home after discharge from the hospital. Further studies are needed to determine if there is an ideal duration of catheterization and whether other at-home treatments have an effect on short-term outcome.
ABBREVIATIONS
FLUTD | Feline lower urinary tract disease |
USG | Urine specific gravity |
Stat profile critical care Xpress analyzer, NOVA Biomedical, Waltham, Mass.
2% chlorhexidine gluconate, Vétoquinol USA Inc, Fort Worth, Tex.
Sovereign Tom Cat Catheter 3.5F, 5.5 inches (14 cm), Tyco Healthcare Group LP, Mansfield, Mass.
Osborne Feline Urethral Catheter, 22 g (1 inch), KVP International Inc, Irwindale, Calif.
Feeding Tube and Urethral Catheter, 3.5F (1.2 mm), 41 cm or 5F (1.7 mm) 41 cm, Tyco Healthcare Group LP, Mansfield, Mass.
IDEXX Reference Laboratories, North Grafton, Mass.
Buster transparent dog collar 12.5 cm, Kruuse, Langeskov, Denmark.
Copies of the survey are available from the corresponding author on request.
R Development Core Team (2011). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.
Prazosin, 0.5-mg capsules, Meds4Vets, Sandy, Utah.
Phenoxybenzamine, 2.5-mg capsules, Kaye's Pharmacy, Baltimore, Md.
Buprenorphine hydrochloride, Reckitt Benckiser Healthcare Ltd, Richmond, Va.
Amoxi-drops, Pfizer Animal Health, New York, NY.
Clavamox suspension, Pfizer Animal Health, New York, NY.
References
1. Buffington CA, Westropp JL, Chew DJ, et al. Risk factors associated with clinical signs of lower urinary tract disease in indoor-housed cats. J Am Vet Med Assoc 2006; 228: 722–725.
2. Lekcharoensuk C, Osborne CA, Lulich JP. Epidemiologic study of risk factors for lower urinary tract diseases in cats. J Am Vet Med Assoc 2001; 218: 1429–1435.
3. Sævik BK, Trangerud C, Ottesen N, et al. Causes of lower urinary tract disease in Norwegian cats. J Feline Med Surg 2011; 13: 410–417.
4. Lee JA, Drobatz KJ. Characterization of the clinical characteristics, electrolytes, acid-base, and renal parameters in male cats with urethral obstruction. J Vet Emerg Crit Care 2003; 13: 227–233.
5. Drobatz KJ, Hughes D. Concentration of ionized calcium in plasma from cats with urethral obstruction. J Am Vet Med Assoc 1997; 211: 1392–1395.
6. Lee JA, Drobatz KJ. Historical and physical parameters as predictors of severe hyperkalemia in male cats with urethral obstruction. J Vet Emerg Crit Care 2006; 16: 103–111.
7. Gunn-Moore D. Feline lower urinary tract disease. J Feline Med Surg 2003; 5: 133–138.
8. Gerber B, Boretti FS, Kley S, et al. Evaluation of clinical signs and causes of lower urinary tract disease in European cats. J Small Anim Pract 2005; 46: 571–577.
9. Segev G, Livne H, Ranen E, et al. Urethral obstruction in cats: predisposing factors, clinical, clinicopathological characteristics, and prognosis. J Feline Med Surg 2011; 13: 101–108.
10. Gerber B, Eichenberger S, Reusch CE. Guarded long-term prognosis of male cats with urethral obstruction. J Feline Med Surg 2008; 10: 16–23.
11. Bovée KC, Reif JS, Maguire TG, et al. Recurrence of feline urethral obstruction. J Am Vet Med Assoc 1979; 174: 93–96.
12. Francis BJ, Wells RJ, Rao S, et al. Retrospective study to characterize post-obstructive diuresis in cats with urethral obstruction. J Feline Med Surg 2010; 12: 606–608.
13. Brady CA, Otto CM, Van Winkle TJ, et al. Severe sepsis in cats: 29 cases (1986–1998). J Am Vet Med Assoc 2000; 217: 531–535.
14. Markwell PJ, Buffington CA, Smith BHE. The effect of diet on lower urinary tract diseases in cats. J Nutr 1998; 128:2753S–2757S.
15. Forrester SD, Kruger JM, Allen TA. Feline lower urinary tract diseases. In: Hand MS, Thatcher CD, Remillard RL, et al, eds. Small animal clinical nutrition. 5th ed. Topeka, Kan: Mark Morris Institute, 2010; 925–976.
16. Buffington CA, Westropp JL, Chew DJ, et al. Clinical evaluation of multimodal environmental modification (MEMO) in the management of cats with idiopathic cystitis. J Feline Med Surg 2006; 8: 261–268.
17. Jones BR, Sanson RL, Morris RS. Elucidating the risk factors of feline lower urinary tract disease. N Z Vet J 1997; 45: 100–108.
18. Stella JL, Lord LK, Buffington CA. Sickness behaviors in response to unusual external events in healthy cats and cats with feline interstitial cystitis. J Am Vet Med Assoc 2011; 238: 67–73.
19. Markwell PJ, Buffington CA, Chew DJ, et al. Clinical evaluation of commercially available urinary acidification diets in the management of idiopathic cystitis in cats. J Am Vet Med Assoc 1999; 214: 361–365.