Lower urinary tract disease Flashcards
What is the vesicoureteral valve?
A valve-like effect formed when the ureter enters the urinary bladder on the serosal surface and tunnels through the bladder wall obliquely to the mucosal surface. The intramural ureter has a “j hook” conformation, Turing from a caudal to cranial direction before entering the trigone
What three factors promote unidirectional flow of urine into the bladder?
Vesicoureteral valve, ureteral peristalsis, and a compliant bladder
What is vesicoureteral reflux?
Reflux of urine back up to the kidneys
What innervation is most important for neurogenically mediated ureteral contraction?
Sympathetic innervation - alpha-1 receptors predominate, but alpha-2, beta-adrenoreceptors all present
What drives normal ureteral peristalsis?
- Myogenic in origin - not neurologic
- When urine enters the ureter, it initiates electrical impulses that are conducted between smooth muscle cells => peristalsis propelled towards the bladder
During obstruction of a ureter, spasmodic contractions occur, which are mediated by what?
Sympathetic input
Stimulate of the ureter with alpha-adrenergic agonist causes what? With beta-adrenoreceptor agonists?
Alpha agonists: ureteral contraction
Beta agonist: ureteral relaxation
What is the most common ureterolith type in dogs and cats?
Calcium oxalate
Conservative medical management of ureteroliths may be attempted if:
- There is minimal renal functional compromise
- No evidence of infection
- No evidence pf progressive ureteral dilation
What is the normal diameter of a cat ureter? Dog ureter?
Cats: 0.3-0.4 mm
Dogs: <2.7mm but varies with breed
In one study, medical management of ureteroliths was successful in what percent of cats?
8-13%
What is the mechanism of action of prazosin and tamsulosin?
Alpha-adrenergic antagonists
Medical management of ureteroliths consists of what therapies?
IV fluid administration, diuretics, alpha-adrenergic antagonists
If medical management of ureteroliths is attempted, what are indications to pursue surgical intervention instead?
Progressive enlargement of the ureter or renal pelvis, worsening renal function, uncontrollable pain, or no movement in 1-2 weeks
For cats, no movement in 24-48 hours
Name 4 urease producing bacteria that may be present with struvite uroliths
Staphylococcus, Proteus, Klebsiella, Corynebacterium, Mycoplasma
Why shouldn’t obstructive struvite ureteroliths be medically managed?
- An obstructed stone is not being bathed in urine, so dissolution is not effective
- Often results in obstructive pyelonephritis which has a high risk of urosepsis
What minimally invasive procedure can be used for the treatment of struvite ureteroliths in dogs?
Retrograde lavage of the renal pelvis and placement of a ureteral stent
Cats typically require surgical, antegrade placement and it’s more difficult
If a ureteral stent is used, when should it be removed or replaced?
Prior to discontinuing antibiotics (may harbor bacteria)
What is shock wave lithotripsy and what species can it be used in?
Uses shock waves generated outside the body and target at the uroliths using integrated fluoroscopy or ultrasonography - used to fragment uroliths in dogs
What percent of uroliths in dogs can be removed via shock wave lithotripsy?
80%, although 50% of dogs require 2+ treatments
Ureteral stents induce passive ureteral dilation, increasing the diameter of the lumen by how much?
3 fold
What is a circumcaval ureter?
Congenital anomaly characterized by ventral displacement or duplication of the caudal vena cava, which crosses over the ureter and results in compression of the proximal ureter - more commonly affects the right side
Uropathogenic E coli contain what adhesion molecule that is expressed by 100% of bacteria that cause pyelonephritis?
Type 1 fimbriae that bind mannose targets on the urothelium
Why are gram negative organisms more likely to cause pyelonephritis than other organisms?
Express adhesion molecules with high affinity for kidney tissue - not typically expressed in other organisms
Rod shaped bacteria are visible on urine sediment examination when the colony count exceeds what number? Cocci bacteria?
Rods: visible if colony count >10,000
Cocci: visible if colony count >100,000
What percent of positive urine cultures are positive for E coli?
Dogs 44-45%
Cats 37%
What substance in cranberries has anti-adherence properties?
Proanthocyanidins with type A linkages - anti-biofilm properties and prevent P-fimbriated UPEC from binding to uroepithelial cells
How is D mannose anti-adherent?
Disrupts bacterial adhesion by blocking the ability of lectins on the tips of type 1 fimbriae to interact with carbohydrate moieties on urothelial cells
How might instillation of glycosaminoglycans into the urinary bladder help prevent UTIs?
E coli virulence factors injury the protective GAG barrier overlying the urothelium. Exogenous GAG may adhere to the urothelium or bind invading bacteria, thus preventing bacteria induced injury
How might estrogen help prevent UTIs in females?
Alters the urinary microenvironment by promoting vaginal Lactobacillus growth, lowering vaginal pH, and restoring atophic mucosa in the urethra - proven in humans, but not dogs
What is the basis of prophylactic antibiotic therapy?
Provide 1/3 to 1/2 the total daily dose of an antibiotic, usually at night after the last void of the day. Antibiotic concentrates in the urine overnight, preventing colonization
How long is prophylactic antibiotic therapy continued?
For 6 months with monthly cultures
At 6 months if the urine is sterile, discontinue antibiotics and monitor for relapse
What is sporadic cystitis (previously called uncomplicated UTI)? What animals should not be managed as sporadic cystitis?
- Bacterial infection of the urinary bladder resulting in compatible lower urinary tract signs in dogs or cats.
- Intact male dogs rarely have sporadic bacterial cystitis - usually bacterial prostatitis is present - treat for this
- Dogs with >3 episodes of cystitis in 12 months should be managed as recurrent bacterial cystitis
A urine culture is preferred in all cases of suspected bacterial cystitis. However, empiric therapy could be considered in what cases?
In dogs with sporadic cystitis that have limited prior antimicrobial exposure
What causes the clinical signs of a UTI? What treatment should be considered in the first few days of UTI treatment?
Inflammation - consider prescribing an NSAID and adding antimicrobials 3-4 days later if clinical signs persist or when the urine culture results are back
If empiric antibiotics are being prescribed for a UTI, what drugs can be used?
Amoxicillin ideally, Clavamox if plain amoxicillin is not available
TMS
How long should sporadic bacterial cystitis be treated? When should a response be seen?
- 3-5 days
- If no improvement in 48 hours, re-evaluate what’s going on
Should a repeat urinalysis or urine culture be performed for sporadic bacterial cystitis?
No as long as the clinical signs have resolved
What is the definition of recurrent bacterial cystitis?
3 or more episodes of bacterial cystitis in the prior 12 months or 2 or more episodes within the prior 6 months
What should be performed for all cases of recurrent cystitis?
Urine culture
- If the pathogen isolated is different from previous organisms, reinfection is likely - identify and address underlying factors
- If a relapsing or refractory infection is present, review the drug, dosing, timing, and client compliance. Then look for underlying factors
For recurrent cystitis cases where re-infection is suspected, how long should antibiotics be prescribed? Should re-culture be performed?
3-5 days - no need to repeat culture/urinalysis if clinical signs resolved
For recurrent cystitis cases where persistent or relapsing infection is suspected, how long should antibiotics be prescribed?
7-14 days
For recurrent cystitis cases where persistent or relapsing infection is suspected, when should the urine be re-cultured?
After 5-7 days of treatment
- Positive culture: evaluate compliance, further diagnostic testing to determine why the bacteria is not cleared
- Negative culture: can determine when to stop therapy
Then 5-7 days after cessation of antimicrobials to help differentiate relapse/persistent infection vs re-infection
For animal with suspected pyelonephritis, when should blood cultures be considered?
In immunosuppressed or febrile animals - perform at the same time as urine culture
When interpreting susceptibility data for pyelonephritis or prostatitis cases, look at the antimicrobial breakpoints for what?
Serum, rather than urine
What should the initial treatment for pyelonephritis be, while waiting for culture results?
- Drugs that have efficacy against Enterobacteriaceae - fluoroquinolone or cefpodoxime reasonable
A diagnosis other than pyelonephritis should be considered if there is no improvement after what time frame?
72 hours of antibiotics, if the culture results say that antibiotic is appropriate
How long should pyelonephritis be treated? What should the follow up be?
- 10-14 days
- Repeat PE, chemistry, UA, and UC 1-2 weeks after stopping antibiotics
What drugs can be used to treat bacterial prostatitis?
TMS, enrofloxacin
What drugs can penetrate the prostatic barrier, but should not be used as empiric treatment as they are not effective against gram negative bacteria?
Clindamycin and macrolides
How long should bacterial prostatitis be treated?
4 weeks in acute cases, 4-6 weeks for chronic disease
Apart from antibiotics, what medical treatments should be considered for dogs with prostatitis?
- Ultrasound guided percutaneous drainage of prostatic abscesses
- Castration or finasteride
Subclinical bacteriuria is defined by what? What does not define it?
Bacteria in the absence of clinical signs
These things do not define it and do not indicate the need for treatment:
- Heavy growth (>100,000 CFU/mL) can be observed
- Pyuria can be observed
- MDR bacteria can be observed
When might you consider treating subclinical bacteriuria?
- Presence of plaque forming (Corynebacterium) or urease producing bacteria due to their ability to cause encrusting cystitis or struvites
Name 5 situations where urine culture may be indicated in animals without lower urinary tract signs
- Suspected pyelonephritis
- Investigation of the bladder as a source of septicemia
- Patients that are to undergo a surgical or minimally invasive procedure that will involve entering the urinary tract
- Suspected struvite stones
- Difficult to regulate diabetics
Prior to cystoscopy or urologic surgery, what should be performed?
Urine culture - if positive, treat based on susceptibility for 3-5 days before the procedure
Should peri-operative antibiotics be used in cystoscopy or urologic surgery?
Only for stone manipulation or open surgical procedures IF the pre-procedure culture was positive for bacterial growth
If peri-operative antibiotics are indicated, when should they be given and what drugs are appropriate?
60 minutes before the procedure, then re-dosed intra-operatively after 2 half lives of the drug have passed
A 2nd generation cephalosporin is appropriate or continue the antimicrobial the patient was already on
All patients with uroliths should have a urine culture performed. How should you act on the results?
- If a urease producing bacteria is identified, treat according to susceptibility - the ISCAID consensus does not recommend treating for the entire course of dissolution
- If a non-urease bacteria is present and the patient has clinical signs of cystitis - treat like a sporadic cystitis
- If no clinical signs, treat like a subclinical bacteriuria
Uroliths smaller than what diameter may not be visible on radiographs, even if they are a radio-opaque stone?
<2mm
At what pH do struvite uroliths form?
> 7
Are calcium oxalate stones more common in males or female? Struvite?
CaOx: males - 78%
Struvite: females - 82%
Uroliths that are typically considered radiolucent may be visible on radiographs if they are larger than what diameter?
> 5 mm
50% of CaOx stones are identified in 6 breeds. Name them
Miniature Schnauzer, Shih Tzu, Yorkshire Terrier, Chihuahua, Bichon Frise, Maltese
What breed is over-represented for both cystine and urate uroliths?
English Bulldog
96% of Dalmatians with uroliths have what stone type?
Urate
If uroliths are <3mm, they can be retrieved via what methods?
During voiding or catheterization
What types of uroliths should be medically dissolved, unless they are causing severe clinical signs or obstruction?
Struvite, urate, cystine
What percent of dogs with CaOx uroliths will have stone recurrence within 2 years of removal?
50%
Name 3 strategies used to prevent the recurrence of CaOx stones
- Feed a high moisture food to reduce USG <1.020 (dogs) or 1.025 (cats)
- Avoid urinary acidification with diet or potassium citrate
- Add hydrochlorothiazide diuretics if needed
How does potassium citrate work to prevent CaOx stones? What is the goal pH?
Augments renal excretion of citrate, which binds calcium and reduces CaOx formation. Goal is a urine pH 7-8
How does hydrochlorothiazide work to reduce CaOx formation?
Increases renal tubular resorption of calcium
Struvite uroliths should be treated with an appropriate dissolution diet and antibiotics. When should rechecks be performed?
4-6 weeks after starting therapy, UA and radiographs are taken
- If USG <1.020, pH <6.5, and the stones have reduced in size by 20% continue therapy and repeat monitoring in 4-6 weeks
To determine an accurate urine pH, it should be measured when?
Just prior to meals or >8 hours after a meal (postprandial alkalinuria is a thing apparently)
Once radiographic resolution of struvite stones has been achieved, how long should you continue therapy?
2-4 weeks
Describe the metabolic pathway of purine degradation?
What is tiopronin (Thiola) and how does it reduce the formation of cysteine stones?
Binds to cysteine to form a more soluble complex than the cysteine dimer (aka cystine)
What cat breeds are overrepresented in urate stones?
Egyptian Maus, Birman, Siamese
What cat breeds are at higher risk of calcium oxalate uroliths?
Persian and Himalayan
What type of crystal is this?
Struvite
What is the composition of diets designed to dissolve struvite stones?
Moderate protein, lower phosphorus and magnesium, promote acidic urine (pH <6.5)
How rapidly do feline struvite stones dissolve and when should they be rechecked?
Faster than dogs - 6-28 days
Recheck 2-4 weeks after starting diet
If a patient with struvite stones will not eat the therapeutic diet, what drug can be used to acidify the urine and assist in stone dissolution?
dl-methionine
What is the composition of diets designed to prevent calcium oxalate stones?
- Avoid over-acidification
- Avoid high sodium (increases Ca elimination)
- Avoid high protein (promotes acidic urine, lower protein promotes diuresis)
- Avoid low phosphorus foods (may stimulate vitamin D production and calcium absorption)
What is the composition of diets designed to prevent cystine stones?
- Avoid over-acidification
- Avoid diets rich in methionine (precursor to cystine - consider low protein or reduced animal protein diets)
- Avoid high sodium diets (enhances cystinuria)
- Can use u/d, jd/, t/d, g/d
What percent of urate stones in Dalmatians were successfully dissolved with diet and allopurinol?
40% dissolved, 30% partially dissolved
When should nephroliths be treated?
- Contributing to outflow obstruction
- Causing recurrent infection
- Causing pain
- Enlarging to the point of causing renal parenchymal compression
What percent of nephroliths in cats are calcium oxalate?
90% - do not attempt dissolution in feline nephroliths
What percent of cats with ureteroliths have concurrent stricture?
20-25%
Hereditary mutations in CaOx1 result in calcium oxalate stone formation. Why?
Gene that produces Tann-Horsfall protein (uromodulin)
- A glycoprotein that is produced by cells in the DCT
- Regulates urinary Ca reabsorption and inhibits urinary crystallization
Mutations in CaOx1 are inherited in what manner? What breeds are predisposed?
Autosomal recessive
- English bulldogs (63%)
- A bunch of other breeds
The prevalence of CKD was how much higher in cats with uroliths than cats without uroliths?
56% vs 30% - screen cats with uroliths for CKD
No association with stage of CKD
Feline cystinuria is associated with a missense mutation in what gene?
SLC3A1
Looking at the trends in feline urolith composition over time, what urolith type has decreased in frequency?
Calcium oxalate - 50% in 2005 to 38% in 2018
Looking at the trends in feline urolith composition over time, what urolith type has increased in frequency?
Struvite = from 42% in 2005 to 55% in 2018
What metabolic derangement is associated with CaOx formation?
Hyperlipidemia - odds increased by 4 for every mmol/L of TG (excluded Miniature Schnauzers)
What is the mean age of first CaOx urolith diagnosis?
8.4 years - recommend screening high risk breeds starting at 5-6 years of age
Polymorphisms in what gene are associated with an increased risk of CaOx urolithiasis and increased urinary excretion of calcium?
Vitamin D receptor polymorphisms
A small subset (32%) of dogs with CaOx stones had what change in vitamin D metabolites?
Decreased conversion of 25(OH)D to 24,25(OH)2D
In a retrospective study of dogs treated for struvite dissolution, what percent achieved full stone dissolution in a median of 35 days?
58%
- Maximum stone diameter, number of stones, and initial pH did not influence outcome
In a retrospective study of dogs treated for struvite dissolution, stones that did not successfully dissolve commonly had what composition?
> 10% non-struvite mineral
In a retrospective study of dogs treated for struvite dissolution, dissolution was more likely in dogs receiving what therapy other than diet?
Antimicrobials (OR 16)
In a retrospective study of dogs treated for struvite dissolution, what percent of dogs experienced adverse effects?
18% - urethral obstructions most common but 3/4 obstructed before trial initiation
Persistent cystotomy site thickening can be present on ultrasound for how long after cystotomy?
3 months
Following cystotomy for stone removal, hyperechoic foci were visible in the bladder on ultrasound in what percent of dogs and when?
61%, median of 17 days post-op :(
Looking at the trends in canine urolith composition over time, what urolith type has decreased in frequency?
CaOx - 50% in 2006 to 42% in 2018
Looking at the trends in canine urolith composition over time, what urolith type has increased in frequency?
Cystine - from 1.4% in 2006 to 8.7% in 2018
Looking at the trends in canine urolith composition over time, what percent of cystine uroliths were from intact male dogs?
70%
In a retrospective study of ureteroceles, what percent were ectopic? What percent had stenotic or imperforate openings?
Ectopic - 70%
Stenotic - 92%
In dogs with idiopathic renal hematuria treated with ACEi or ARB, what percent had complete resolution of hematuria?
42%, partial improvement in 26%
In dogs with recurrent UTI, what were the most common cystoscopic findings?
Mucosal edema, vestibulovaginal septal remnant, lymphoid follicles, short urethra, and ectopic ureters
In dogs with recurrent UTI, what percent of dogs had abnormalities on cystoscopy?
85%
In a study of antibiotic resistance among E coli, bacteria isolated from cat urine were 100% resistant to what antibiotics?
Amoxicillin and Clavamox
In a study of antibiotic resistance among E coli, bacteria isolated from dog urine had what susceptibility to amoxicillin and Clavamox?
Amoxicillin - only 53% were susceptible
Clavamox - 92% susceptible
In a study evaluating the effects of USG and pH on E coli growth, E coli grew best in what conditions?
Neutral to acidic urine, diluted urine
Dogs with recessed vulvas had what other PE finding compared to dogs without recessed vulvas?
Higher BCS and body weights
Dogs spayed at <1 year of age were how many times more likely to have vulvar recession?
3x
In one study, were recessed vulvas associated with clinical signs?
No - no association with UTIs, LUT signs, or perivulvar dermatitis in 36 dogs
What percent of dogs with CKD had a positive urine culture? What percent were symptomatic?
32% positive, 8% symptomatic
So high frequency of bacteriuria, but likely subclinical
What were the risk factors for a positive urine culture in dogs with CKD?
Female, isosthenuria
What endocrine disease is NOT a risk factor for subclinical bacteriuria in cats?
Hyperthyroidism
In cats with SUBs or ureteral stents, what percent develop positive urine cultures in the 200 days post-operatively?
25% - almost all clinical (UTI or pyelo vs subclinical bacteriuria)
In cats with SUBs or ureteral stents, what was the most commonly identified bacteria?
Enterococcus
What is a risk factor for the development of Candida UTI in dogs and cats?
Antibiotic administration in the prior 30 days
What are the risk factors for Enterococcus UTI?
- Recurrent bacteriuria was more common with Enterococcus infection compared to E coli
- LUT anatomic abnormalities, neoplasia, or urolithiasis
Cats with subclinical bacteriuria are more likely to have what risk factors?
Female in multiple studies
CKD in one study, hepatic disease in another study
What nerve provides parasympathetic innervation to the detrusor muscle and where does that nerve arise? What type of receptor is involved?
Pelvic nerve - S1-S3
M3 muscarinic receptors
What effect does parasympathetic stimulation have on the bladder?
Leads to contraction of the detrusor and emptying of the bladder
Parasympathetic = Pee
Inappropriate dysfunction of the pelvic nerve leads to what conditions?
- Inappropriate stimulation - overactive bladder
- Inappropriate blockage - bladder atony and urine retention
What nerve provides sympathetic innervation to the detrusor muscle and where does that nerve arise? What type of receptor is involved?
Hypogastric nerve - L1-L4
Beta-3 adrenergic signaling
What effect does sympathetic stimulation have on the bladder and urethra?
- Detrusor relaxation and filling
- Contraction of the urethral sphincter and continence
Sympathetic and somatic = storage
Inappropriate dysfunction of the hypogastric nerve leads to what conditions?
- Inappropriate stimulation - Urine retention
- Inappropriate blockage - decreased bladder compliance and increased filling pressure; open urethra and incontinence
What nerve provides sympathetic innervation to the bladder neck and urethra? What type of receptor is involved?
Hypogastric
Alpha-1 adrenergic stimulation
What nerve provides somatic innervation to the distal urethra and pelvic floor muscles and where does that nerve arise? What type of receptor is involved?
Pudendal - S1-S2
Nicotinic receptors
What effect does somatic stimulation have on the bladder/urethra?
Conscious or reflex contraction and continence
Sympathetic and somatic = storage
In the male dog, what type of muscle predominates in the prostatic urethra? The rest of the urethra?
Prostatic urethra = smooth muscle
Rest of the urethra
>50% skeletal muscle
9% smooth muscle
In the female dog, what type of muscle predominates in the urethra?
- The internal sphincter is smooth muscle and extends distally to the cranial half of the urethra
- Striated muscle comes in caudal to the vagina
In the male dog, where are the internal and external urethral sphincters located?
- Internal: between the trigone and start of the prostate - innervated by the hypogastric nerve
- External: at the caudal end of the prostate, innervated by the pudenal nerve
During filling and storage, activation of stretch receptors in the bladder wall leads to what?
Reflex arc - increases urethral tone and relaxes the detrusor muscle via sympathetic pathways
What occurs during the initiation of micturition (full bladder)?
Stretch receptors send afferent signals along the myelinated fibers of the pelvic nerve to the lumbar spinal cord and the pontine micturition center of the brain
- If urination is appropriate, parasympathetic pathways are activated to stimulate bladder smooth muscle contraction and sympathetic pathways are inhibited to relax the urethra
Why do storage disorders occur?
Inability to maintain adequate urethral tone in the face of normal bladder pressure
What is the mechanism of action of phenylpropanolamine?
Alpha-agonist - stimulates the receptors in the internal urethral sphincter to promote continence
Why are DES or other estrogen products used to treat USMI?
Thought to increase the number and sensitivity of alpha-receptors in the urethral sphincter
What percent of female dogs with respond to PPA? Males?
Females: 75-90%
Males: 40%
What are the risks of estrogen compounds in males and in cats?
Males: risk of prostatic metaplasia - do not use
Cats: risk of mammary gland neoplasia, monitor closely
Lesions in what part of the spinal cord lead to a lower motor neuron bladder?
S1-S2 - leads to weakness of the striated muscular sphincter, bladder atony and an easily expressible bladder
What are other symptoms of a lower motor neuron bladder?
Decreased anal tone, poor perineal reflex
What is detrusor hyperreflexia or overactive bladder?
Sudden urge to urinate and involuntary loss of urine associated with bursts of detrusor contraction at bladder volumes far below capacity
How is detrusor hyperreflexia treated?
Antimuscarinic drugs - oxybutynin or imipramine
How is detrusor hyperreflexia diagnosed?
Difficult in dogs - urodynamic studies and cystometrography or a therapeutic trial with a antimuscarinic
What is thought to be the underlying cause of DUD?
A lesion in the reticulospinal tract, Onuf’s nucleus, or the caudal mesenteric ganglion => loss of inhibitory signals to the pudendal or hypogastric nerves and failure of the urethral sphincter to relax
What is a normal residual bladder volume?
<0.5mL/kg
What is the difference between prazosin and tamsulosin?
Prazosin: alpha1-specific antagonist with effect on both the internal and external urethral sphincter
Tamsulosin: alpha1A-specific antagonist - subtype found on the internal urethral sphincter
If the external urethral sphincter is involved in DUD, what drugs can be used?
Diazepam or other skeletal muscle relaxants (acepromazone, methocarbamol)
Damage to what part of the spinal cord leads to an upper motor neuron bladder?
Cranial to the sacral segment - usually thoracolumbar
What causes an upper motor neuron bladder?
Loss of inhibitory signals to the hypogastric and pudendal nerves that prevents the sphincter to relax on voiding - difficult to express
What is dysautonomia?
Degeneration of the neurons of the autonomic ganglia - leading to sympathetic and parasympathetic dysfunction
In a retrospective study of 45 cats, what were the most common causes of urinary incontience?
- Spinal cord trauma: 20%
- Congenial anomalies: 18%
- Urethral stricture: 13%
- Inflammation associated detrusor dysfunction 13%
In a retrospective study of 45 cats, what percent of cats had urinary incontience due to iatrogenic trauma?
22% - urethral stricture due to PU or catheterization most common
In a retrospective study of 45 cats, what percent of cats with urinary incontience had UTIs?
39%
In a retrospective study of 45 cats, what cats were more likely to have voiding disorders as a cause of urinary incontience?
Younger, males
In a retrospective study of 45 cats with urinary incontience, what percent improved with treatment?
50%
