Peer Reviewed

FELINE URETHRAL OBSTRUCTION: DIAGNOSIS & MANAGEMENTFELINE URETHRALOBSTRUCTION: DIAGNOSIS& MANAGEMENT
Christopher M. George, DVM, and Gregory F. Grauer, DVM, MS,
Diplomate ACVIM (Small Animal Internal Medicine),
Kansas State University

Feline urethral obstruction (UO) is a common
disorder encountered in small animal emergency
practice, with incidence estimates ranging from
1.5% to 9%.1,2
The etiology of UO was long thought to be aphysical obstruction, such as a urethral plug, calculi,
stricture, or neoplasia. In a recent study,3 however,causes of UO in 45 cats were found to be idiopathic(53%), uroliths (29%), and urethral plugs (18%),
indicating that functional obstructions may be morecommon than previously thought.
Feline UO is a treatable emergency, with a survival
rate to discharge higher than 90%,1 despite the factthat it is potentially life threatening due to severe
electrolyte and acid–base imbalances secondary
to acute postrenal azotemia/uremia.1,4 Treatmentcommonly involves days of hospitalization,with substantial owner investment, and rates ofrecurrence following treatment are relatively high(range, 11%–43%).3,5

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Article36

signs—associated with the onset of uremia—include
anorexia, vomiting, and lethargy/collapse.
Clinical signs depend on the completeness andduration of the obstruction. The median durationof signs before veterinary presentation was 3 days in
one study of 223 cats.1

PREDISPOSING FACTORS
Given their relatively long and narrow urethra, malecats are much more likely than female cats to develop
obstruction. Segev and colleagues determined thatthe mean age of cats with UO (51.7 ± 37.7 months)
was significantly lower than gender-matched andtime-matched (sequential hospital admissions)controls without UO (75.5 ± 61.3 months).4 In
addition, obstructed cats were more likely to liveindoors only, weigh more, and be fed a dry dietexclusively.4

Physical Examination
The classic physical examination finding in cats with
UO is an overdistended, turgid urinary bladder thatcannot be expressed. It is important to note, however,that the inability to express urine can be a normal
finding in male cats and not diagnostic for UO.
The penis may be reddened from self-trauma, anda urethral plug may be observed protruding fromthe tip of the penis. Dehydration may be present
as indicated by prolonged skin turgor and tacky
mucous membranes.
Moderate bradycardia (100–140 beats/min)and severe bradycardia (< 100 beats/min) wereobserved in 6% and 5% of cases, respectively.1
Bradycardia and arrhythmias occur secondary to
the effects of hyperkalemia on cardiac conduction.1
Of cats with UO, 50% can be expected to have anormal body temperature, 40% hypothermic, and
10% hyperthermic.1 In one study, the combinationof hypothermia (< 95–96.6°F) and bradycardia(< 120 beats/min) was 98% specific for severe
hyperkalemia (> 8 mEq/L).6
Systolic blood pressure on presentation istypically normal7; in one study, 71% of cats were
normotensive and 29% were hypertensive.7

PRESENTATIONClinical Signs
The most common early clinical signs of UO aresimilar to those of idiopathic cystitis, including
stranguria, dysuria, and hematuria. Delayed systemic

INITIAL DIAGNOSTICS
Diagnosis and management of UO are performed
simultaneously. Diagnostics should ideally include:• Minimum database, including packed cellvolume/total solids, blood urea nitrogen (BUN),

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FELINE URETHRAL OBSTRUCTION: DIAGNOSIS & MANAGEMENT

creatinine, blood glucose, pH, sodium, potassium,chloride, phosphorus, and ionized calcium• Electrocardiogram• Urinalysis with sediment examination• Abdominal/perineal radiographs.
Blood Analysis
In one study of cats with UO1:
• Serum creatinine concentration was above thereference range in 29% of cats
• BUN was above the reference range in 33% of cats
• Serum phosphorus was above the reference range
in 25% of cats.
Hyperkalemia is one of the most common
laboratory abnormalities observed in cats with
UO and can contribute to severe bradycardia andarrhythmias. In one study of cats with UO, serum
potassium concentration was1:• Less than 6 mmol/L in 76% of cats
• 6 to 7.9 mmol/L in 12% of cats
• 8 to 10 mmol/L in 12% of cats
• Above 10 mmol/L in only 0.5% of cats.
Hyperkalemia was also most often encounteredwith acidosis and low serum ionized calcium
concentrations.1 In cats with UO and bradycardia
and/or arrhythmias, the magnitude of hyperkalemia
should be assessed and corrected prior to sedation or
anesthesia for urethral catheterization.
Urinalysis
If urine is available, the urine specific gravity (USG)
may be greater than 1.040 early in UO, but more
dilute urine can be observed with prolonged UO
as a result of increasing renal tubular dysfunction.
Microscopic hematuria is almost always present,
and gross hematuria is common due to bladder
overdistension and/or the presence of underlying
cystitis. Hematuria is also frequently associated withpyuria and proteinuria.
Nearly all cats presenting for UO have sterile urine;
however, urine contamination or misinterpretationof particulate matter in the urine sediment may
be mistaken for a urinary tract infection (UTI).
Quantitative bacterial culture of urine obtained bycystocentesis is recommended to confirm UTI in
patients with suspected infection. Struvite crystals
may be observed as well, especially in alkaline urine.
Struvite crystals are more likely to form secondary tourine stasis and alkalinuria as opposed to being the
primary cause of UO.
Imaging
All cats with UO should be evaluated with abdominal

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radiography to rule out urolithiasis as a cause. It
is important to make sure the radiographs include
the entire urinary system, which allows the kidneys,ureters, bladder, and entire length of the urethra to beassessed for urolithiasis.
Free abdominal fluid, as indicated by loss of serosal
detail in the caudal abdomen, may be observed but is
not always caused by rupture of the urinary bladder.8
Increased bladder permeability secondary to severe
distension and diffuse cystic mural disease may resultin transmural leakage of urine without overt bladderrupture. Positive-contrast urethrography/cystography
is the most sensitive diagnostic test for bladder or
urethral rupture.
Ideally, survey radiographs are obtained prior topassage of a urethral catheter because the presenceof the catheter can make urethral evaluation moredifficult, and urolithiasis may be undetected. If
the patient is in critical condition, steps to address
metabolic derangements should have priority overradiographs.
PATIENT STABILIZATION
The magnitude of azotemia, electrocardiographic
stability, and degree of bladder distension helps
dictate the order of treatment and how quickly it
must be performed. Cats in uremic crisis with verylarge, turgid bladders require prompt intervention.
Stabilization of the patient and treatment ofadverse effects of UO are essential before anesthesia isadministered. Hypovolemia and hyperkalemia must
be the first treatment priorities.
Fluid Administration
Intravenous access should be obtained soon after
presentation because IV fluid administration is criticalfor severely ill cats with UO.
Crystalloid fluid therapy is indicated; 0.9% sodium
chloride is often recommended because it does notcontain potassium. However, in a randomized study
comparing treatment with 0.9% sodium chloride anda balanced polyelectrolyte solution (Normosol-R,
hospira.com), no difference was observed in the rateof decline of serum potassium; in addition, a more
rapid correction of acidosis was observed in the catstreated with polyelectrolyte solution than in thosetreated with 0.9% sodium chloride.9 This suggeststhat balanced electrolyte solutions may actually be
preferred for correcting acid–base imbalances in catswith UO.
IV fluid therapy is started at a rate of 10 to 20 mL/
kg/H, and the rate adjusted as the patient stabilizes
and urethral patency is established. Mild increases

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FELINE URETHRAL OBSTRUCTION: DIAGNOSIS & MANAGEMENT

Degrees ofHyperkalemia

Various degrees of hyperkalemia occur in cats with UO (Table). Hyperkalemia adversely affects cardiac
conduction. As a result, tall and spiked T waves, widened QRS complexes, lengthened PR intervals,
flattened P waves, atrial standstill, ventricular fibrillation, and/or asystole may be observed on a lead II
ECG rhythm strip (Figure).

Table.
Cats with Urethral Obstruction: Degrees of Hyperkalemia
DEGREE OF
HYPERKALEMIASERUMPOTASSIUM
CONCENTRATIONTREATMENT OPTIONS

Mildhyperkalemia< 6 mEq/L

Dilutional fluid therapy (10–20 mL/kg/H), with rate adjusted as patientstabilizes

Moderate
hyperkalemia

6–8 mEq/L

IV administration of:• Dextrose (50% solution [1 mL/kg]
diluted to final concentration of
10%–20%)• Regular insulin (1 U)

Severehyperkalemia> 8 mEq/L

Calcium gluconate (0.5–1 mL/kg
IV), followed by regular insulin anddextrose IV

in serum potassium concentrations will return toreference intervals with dilutional fluid therapy
and relief of UO; however, targeted correction ofmoderate to severe hyperkalemia is necessary prior
to sedation or anesthesia for relief of the UO (seeDegrees of Hyperkalemia).
Calcium Gluconate
Calcium gluconate is the treatment of choice forcats with severe hyperkalemia, bradycardia, andelectrocardiographic instability.
Calcium gluconate (10%) is administered at 0.5
to 1 mL/kg IV slowly over 2 to 3 minutes while
continuously monitoring the electrocardiogram.
If bradycardia worsens or QT interval shortening
occurs, the infusion should be stopped.
While this treatment rapidly stabilizes cardiac
conduction, it does little to reduce hyperkalemia. In
addition, its beneficial effects are short lived (20–30
min) and other strategies to lower serum potassium
are often needed (Table).
An IV infusion of calcium gluconate may also be
administered to treat muscle twitching or seizures
associated with hypocalcemia. Hypocalcemia usuallyresolves rapidly after relief of obstruction as serum
phosphorus concentration decreases.
Dextrose
IV dextrose is helpful for longer term control ofhyperkalemia. A 50% dextrose solution (1 mL/kg), diluted to a final concentration of 10% to38

Figure. Examples of how different degrees
of hyperkalemia can adversely affect cardiac
conduction. Picture the lead II rhythm strip as astring being pulled apart. Note the flattened P
waves, prolonged PR interval, and widened QRS
complexes. The exception to this string analogy
is the tall, spiked T waves.

20%, is administered as an IV bolus. This treatment
stimulates endogenous insulin release, causing
intracellular translocation of plasma potassium.
Administration of 1 unit of regular insulin IV
hastens the intracellular translocation process.
However, insulin should never be given without aconcurrent dextrose bolus, followed by a constantrate dextrose infusion to prevent hypoglycemia.
Sodium Bicarbonate
Sodium bicarbonate may be administered in cats withsevere hyperkalemia to help translocate potassiumfrom the plasma into the intracellular fluid in exchange
for hydrogen ions. Sodium bicarbonate (1 mEq/kg) isadministered IV, with a maximum dose of 4 mEq/kg.
If excessive amounts of bicarbonate areadministered, the major disadvantage of thistreatment is the development of ionized hypocalcemia
due to increased binding of calcium to albumin

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FELINE URETHRAL OBSTRUCTION: DIAGNOSIS & MANAGEMENT

and intracellular translocation of ionized calcium,
creating an alkalemia. Sodium bicarbonate may also
be less effective than dextrose or insulin in reducing
potassium concentrations.
Cystocentesis
Therapeutic cystocentesis should be performed assoon as possible in cats with very large bladders andprior to anesthesia for urethral catheter placement
to aid in stabilizing the patient. The benefits oftherapeutic cystocentesis almost always outweigh thepotential adverse effects; benefits include:• Rapid reduction of bladder pressure• Improvement in glomerular filtration rate
• Collection of an uncontaminated urine sample• Reduction of cystic pressure, which may facilitate
urethral catheterization and back flushing.
Cystocentesis in cases of UO is considered
controversial by many clinicians, with the major
concern being bladder rupture or tear. However,clinical experience and recent evidence have shownthat the overall risk for bladder rupture is low.8,10 In
a recent study of 47 cats with UO, decompressive
cystocentesis, followed by urethral catheterization,
had no significant adverse effects on the bladder.8 In
most cases, a needle hole in the bladder resulting in aclinically significant uroabdomen is unlikely, especially
if the bladder is kept decompressed by placement of aurinary catheter.10
To reduce potential complications of bladderlaceration and aortic puncture:• Perform the procedure with the cat in lateralrecumbency• Use a 22-gauge needle attached to an extension
set with a 3-way stopcock and 35-mL syringe; theextension tubing and 3-way stopcock allow the
bladder to be emptied at least partially without
manipulation and movement of the needle• Advance the needle through the bladder wall at a
45-degree angle directed toward the trigone; the45-degree angle helps the needle tract seal after
withdrawal• Stabilize the bladder with one hand while the other
hand guides the needle and an assistant operates
the syringe.
URETHRAL OBSTRUCTION RELIEF
Anesthesia
After the cat has been stabilized, sufficient anesthesia
is administered to provide immobilization andurethral relaxation. Many effective anesthesia
protocols are available and can be chosen based onclinician comfort and drug availability.

Peer Reviewed• Ketamine (2–5 mg/kg IV), with either diazepam(0.2–0.5 mg/kg IV) or acepromazine (0.005–0.05
mg/kg IV), is generally a safe and effective
protocol; a second dose of ketamine and diazepam
can be administered if additional time is needed tocomplete the procedure.
• Diazepam may be a better choice for morecritical patients because it is less likely to cause
hypotension compared with acepromazine.
• Inhalational anesthesia (isoflurane or sevoflurane)
via endotracheal tube may be necessary in somecats that are not sufficiently relaxed with the above
protocols.
• Propofol is also effective, but apnea andhypotension are possible adverse effects. If
propofol is used, the cat should be intubated toprovide adequate ventilation.
Epidurals provide analgesia to the penis andbladder and may reduce the depth of anesthesia
necessary, but these techniques require additional
training and expertise. A simplified method ofcoccygeal epidural with local anesthetic has been
described and provides safe and effective analgesia to
the penis and urethra.11
Urethral Catheter Placement
Aseptic technique and a gentle hand are fundamental
to urethral catheter placement.
1. Clip the hair in the perineal region carefully andprepare the skin aseptically.
2. Extrude the penis and retract it caudally tostraighten the urethra. Failure to fully retract
the penis caudally impedes the catheter fromnavigating the sigmoid flexure of the urethra.
3. Advance a urinary catheter (see What Types ofCatheters?, page 40) into the urethra to the site ofobstruction. Advance the catheter slowly to avoid
urethral trauma; it should never be forced past an
obstruction.
4. Urethral irrigation (hydropulsion) with sterile
physiologic saline via an extension tube isrecommended both to dilate the urethra and to flush
any obstructing material retrograde into the bladder.
5. A 50:50 mixture of water-soluble lubricant andsterile physiologic saline may also be injected
through the catheter to provide lubrication along
the entire length of the urethra and aid in catheter
advancement.
6. Once the urethra is patent, flush it thoroughly toensure all debris is removed and then advance thecatheter into the bladder.
7. After catheterization, flush and drain the bladdermultiple times with sterile saline to remove

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FELINE URETHRAL OBSTRUCTION: DIAGNOSIS & MANAGEMENT

What Types ofCatheters?

For urethral catheter placement, use a welllubricated, rigid, open-ended urinary catheter(eg, 3.5- or 5-Fr, 10-cm polypropylene). A 20- to
22-gauge over-the-needle catheter (without theneedle) or olive-tip catheter may also be used;however, these are not usually long enough toreach the trigone and drain the bladder.
For indwelling catheter placement, usea longer, softer catheter; material options
include polyvinyl (red rubber catheter orinfant feeding tube), polytetrafluroethylene(Slippery Sam Tomcat Urethral Catheters,
surgivet.com), or polyurethane. A 3.5-Fr
catheter is preferred over a 5-Fr catheter
because the smaller diameter catheter isassociated with a decreased incidence ofrecurrent UO within 24 hours (in one study,
6.7% of cats with a 3.5-Fr catheter versus 19%
of cats with a 5-Fr catheter).5 Polypropylene
catheters should not be used as indwelling
catheters because they tend to be more
irritating to the urethra than other types ofurinary catheters.12

debris and help prevent rapid recurrent UO. We
use refrigerated sterile saline to help promote
vasoconstriction and reduce hemorrhage.
Role of Atracurium Besylate
One study evaluated the effect of intraurethral
atracurium besylate—a neuromuscular blocking agent
that causes paralysis of striated muscle—in male catswith urethral plugs in aiding the resolution of UO.13• A solution of 0.5 mg/mL atracurium besylate wasinfused into the urethral lumen of treated cats for
5 minutes prior to retrograde flushing; the control
group was infused with saline.
• The percentage of cats with urethral plug removal
at the first attempt was significantly higher in theatracurium group (64%) compared with the salinegroup (15%).
• The mean time required for removal of the UO
was also significantly reduced in the atracurium
group.
Use of this protocol may result in shorter anesthetic events and easier urethral catheterization incats with UO.
Indwelling Catheters
Indwelling urethral catheters are not necessary in
all cases of UO because the presence of the catheter
causes urethral irritation. However, indwelling
urethral catheters are necessary in patients with:• Severe azotemia, which often results in40

postobstructive diuresis (requiring measurement ofurine production to guide fluid therapy; see After
Relief of Urethral Obstruction)• Severe bladder distension, which often results in
detrusor atony and inability to void
• Grossly abnormal urine or cystic calculi, both ofwhich increase the risk for immediate recurrent UO.
To avoid trauma to the bladder mucosa and thecatheter tangling inside the bladder, indwelling
urethral catheters (see What Types of Catheters?)
should not be inserted fully into the bladder.
Catheters should be “premeasured” and inserted only
to the level of the trigone. The indwelling catheter isthen secured to the prepuce using a nonabsorbablesuture and finger trap technique, tape butterfly andsuture, or other technique depending on clinician
preference.
A sterile collection system should always be
attached and secured to the cat’s tail. It is neveracceptable to leave an indwelling catheter exposedto the environment due to the risk for bacterial
infection. An Elizabethan collar or hind leg hobbles
should be used to prevent the cat from chewing out
the catheter.
AFTER RELIEF OF URETHRALOBSTRUCTION
After obtaining urethral patency, intensive supportive
care is indicated until resolution of metabolic
derangements. This care includes:• Maintenance of urethral catheter• Monitoring for postobstructive diuresis andsecondary UTI• Administration of IV fluid therapy, analgesia, andurethral relaxants/antispasmodics• Potential supplementation with potassium.
Postobstructive Diuresis
Postobstructive diuresis (POD) is a well-describedphenomenon in human medicine that may result
secondary to UO in cats as well. In one study, 46%(13/28) of cats developed POD, defined as urine
production exceeding 2 mL/kg/H within 6 hours
after relief of UO.15 Several cats had diuresis up to 84
hours following relief of UO.15
The high incidence of POD calls for close
measurement of urine output and continued IV fluid
administration using an “ins and outs” fluid therapy
protocol after resolution of hypovolemia. This
protocol involves administering balanced electrolyte
fluids at a rate to replace the urine volume produced
hourly, plus 20 mL/kg/day for insensible losses toprevent negative fluid balance.

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FELINE URETHRAL OBSTRUCTION: DIAGNOSIS & MANAGEMENT

Conventional management of UO can involve
substantial owner expense. Financial constraints
may result in euthanasia of cats with UO,
especially those with recurrent UO. Whileconventional management with urethral catheter
and intensive care should always be offered as
the first treatment choice, a noncatheterization
protocol may be a viable alternative toeuthanasia.
In a 2010 study, Cooper and colleagues
described a protocol for managing UO in malecats without urethral catheterization14:
1. Acepromazine (0.25 mg IM) and buprenorphine(0.075 mg IM) are administered to provide
sedation and analgesia.
2. The penis is inspected and gently massaged in
an attempt to dislodge any obstruction in the
distal penis, followed by a single attempt to
express the bladder.
3. If no urine is expressed, therapeutic cystocentesis is performed and the cat is housed in adark, quiet room to minimize stress.

4. Acepromazine (2.5 mg PO Q 8 H) andbuprenorphine (0.075 mg PO Q 8 H) areadministered, with cystocentesis repeatedevery 8 hours. Medetomidine (0.1 mg IM Q 24
H) can be administered if no urination is noted
within 24 hours, and SC fluids can be given as
needed.
Treatment success, defined as spontaneous
urination within 72 hours, occurred in 11 of 15(73%) cats; treatment failure occurred in 4 of
15 (27%) cats. Cats that experienced treatment
failure had significantly higher serum creatinine
concentrations, although the magnitude of
pretreatment azotemia was not an exclusionary
criterion. Necropsy of 3 of the cats with treatment
failure showed no evidence of bladder rupture.14
Cats with unresponsive mentation, severe
metabolic derangements (severe acidosis or
hyperkalemia), or radiographic evidence ofuroliths were excluded from the study and are
not good candidates for this protocol.14

Monitoring & IV Fluid Rate
Serum electrolytes should be monitored at minimum
every 24 hours, and potassium supplementation may
be required to prevent hypokalemia, especially in theface of substantial POD. Reduced urine production
typically occurs after resolution of azotemia.
If urine production does not decrease, the highrates of IV fluids may be driving the diuresis. The IV
fluid rate in these patients should be tapered initiallyby 25%. If urine production decreases, continued
reduction of IV fluids by 25% every 6 to 12 hours is
recommended. If urine production is not reduced, thefluid rate should be increased to its previous level andtapering attempted again 24 hours later.

Indwelling Catheter Removal
The duration of indwelling urethral catheterization iscontroversial. Removing the indwelling catheter too
soon may not allow for adequate clearing of bladderdebris, clots, or crystals. However, the presence of aurinary catheter causes irritation and inflammation of
the lower urinary tract.13
The duration of urethral catheterization should
be based on the patient’s clinical status rather
than a specific amount of time. Guidelines forcatheter removal include resolution of metabolic
derangements (such as azotemia) and POD as well as
improvement in the gross character of the urine (clear
versus cloudy/hemorrhagic).10 The average durationof indwelling catheterization is 48 hours.

Analgesics
Continued treatment with analgesics for 5 to 7 days
after relief of UO is indicated in all patients. Opioid
derivatives (eg, buprenorphine) are used mostcommonly.
Use of the nonsteroidal anti-inflammatory drug
(NSAID) meloxicam was evaluated recently in thetreatment of obstructive feline idiopathic cystitis.16
Cats were separated into 2 treatment groups: one
receiving buprenorphine and meloxicam and the otherreceiving buprenorphine and a placebo. Meloxicam
did not influence the recurrence rate of UO or rateof recovery from clinical signs. Due to these findings
and the risk associated with NSAIDs in the face ofhypovolemia and decreased renal function, NSAIDs
should be used with caution in cats with post-UO.

Peer Reviewed

Avoiding
Euthanasia:
Nonconventional
Management

Use of Antimicrobials
Antimicrobials are not recommended unlessquantitative bacterial culture demonstrates thepresence of a UTI. The majority of cats presenting fortheir first UO do not have a UTI, and antimicrobials
do not prevent the development of catheter-associated
UTI.
A prospective study of cats with UO found zero
positive cultures on presentation, but 6 of 18 (33%)
cats developed UTI while catheterized.17 Cats treatedwith an indwelling urethral catheter should have aquantitative bacterial culture performed on urine at
the time of catheter removal or 7 to 10 days later.
Antimicrobials should be prescribed based on culture
and sensitivity results.

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FELINE URETHRAL OBSTRUCTION: DIAGNOSISFELINE& MANAGEMENTURETHRAL OBSTRUCTION

Urethral Relaxants
Because urethral irritation and spasm can contributeto UO, the use of urethral relaxants has become
standard. Medications most commonly used include
acepromazine, phenoxybenzamine, and prazosin, allof which function as alpha-1 antagonists, which causesmooth muscle relaxation. Since smooth muscle islocated in the proximal 1/3 of the penile urethra only,
whereas striated muscle comprises the remainder ofthe urethra, urethral relaxants may not be effectivein improving outcome in cats with more distal
obstructions.
One retrospective study evaluating factors affecting
recurrent UO rates found that patients receiving
prazosin had significantly lower recurrent UO rates
than those receiving phenoxybenzamine at 24 hours(7% versus 22%, respectively) and 30 days (18%versus 39%, respectively).5 This may be due to themore rapid onset of action of prazosin compared withphenoxybenzamine as well as the effects of prazosin
on both the preprostatic and prostatic urethra.
Therefore, prazosin (0.25–1 mg/cat PO Q
8–12 hours) is recommended in cats for 5 to 10
days post-UO. However, phenoxybenzamine or
acepromazine may be substituted based on availability.
It is important to consider the sedative effects ofacepromazine, as these may be beneficial in reducing
stress or contraindicated based on the individual
patient.
Further prospective studies are needed to evaluate
the effects of other alpha-1 antagonists on recurrent
UO.
AFTER DISCHARGE
Home Environment
The home environment of cats with UO should bechanged as needed to help decrease stress and increasewater consumption. Alterations may include:• Increasing contact time between the cat and owner• Improving litter box hygiene and increasing
number of litter boxes• Switching to a canned food diet and increasingwater availability• Environmental enrichment, such as vertical perches
and hiding places• Increasing hunter behavior and use of pheromones(Feliway spray, feliway.com) to help reduce stress.18
In a prospective study evaluating risk factors
associated with recurrent UO, the combination ofenvironmental modifications significantly lowered
the risk for recurrent UO, but increasing water
consumption was the only independent factor
associated with a decreased risk for recurrent UO.19
42

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FELINE UrETHrAL OBSTrUCTION: DIAGNOSIS & MANAGEMENT

Follow-Up
re-evaluation 7 to 10 days after discharge isrecommended. Factors to evaluate include:• Urinalysis to monitor USG (goal of < 1.030),
urine pH, and crystalluria• Quantitative bacterial culture (obtained bycystocentesis) to rule out UTI that may
have occurred during indwelling urethralcatheterization.
IN SUMMARYUO is a common but complex disorder encounteredin cats. A great deal remains to be learned about thetreatment of UO and the risk factors for recurrent
UO to help standardize care. Despite the severe
metabolic consequences associated with UO,
aggressive treatment results in high success rates.
When aggressive conventional treatment is not
an option, nonconventional management may besuccessful.
BUN = blood urea nitrogen; NSAID = nonsteroidal
anti-inflammatory drug; POD = postobstructive
diuresis; UO = urethral obstruction; USG = urine
specific gravity; UTI = urinary tract infection
References
1.

2.

3.

4.

5.

Lee JA, Drobatz KJ. Characterization of the clinicalcharacteristics, electrolytes, acid-base, and renal parameters
in male cats with urethral obstruction. J Vet Emerg Crit Care
2003; 13(4):227-233.
Lekcharoensuk C, Osborne CA, Lulich JP. Evaluation oftrends in frequency of urethrostomy for treatment of urethralobstruction in cats. JAVMA 2002; 221(4):502-505.
Gerber B, Eichenberger S, reusch CE. Guarded long-term
prognosis in male cats with urethral obstruction. J Feline Med
Surg 2008; 10:16-23.
Segev G, Livne H, ranen E, Lavy E. Urethral obstruction
in cats: Predisposing factors, clinical, clinicopathologicalcharacteristics and prognosis. J Feline Med Surg 2011;
13:101-108.
Hetrick PF, Davidow EB. Initial treatment factors associated

CHRISTOPHER M. GEORGE

Christopher M. George, DVM, is asmall animal internal medicine resident
at Kansas State University College
of Veterinary Medicine. Dr. George
received his DVM degree from Kansas
State University and completed a small
animal surgery and medicine internshipat VCA Mission Animal Referral andEmergency Center before returning
to Kansas State University for his
residency training. His clinical interests
and Master’s research include feline
chronic kidney disease and urology.

44

with feline urethral obstruction recurrence rate: 192 cases(2004-2010). JAVMA 2013; 243(4):512-519.
6. Lee JA, Drobatz KJ. Historical and physical parameters as
predictors of severe hyperkalemia in male cats with urethralobstruction. J Vet Emerg Crit Care 2006; 16(2):104-111.
7. Malouin A, Milligan JA, Drobatz KJ. Assessment of bloodpressure in cats presented with urethral obstruction. J Vet
Emerg Crit Care 2007; 17(1):15-21.
8. Hall J, Hall K, Powell L, Lulich J. Outcome of male catsmanaged for urethral obstruction with decompressive
cystocentesis and urinary catheterization: 47 cats (20092012). J Vet Emerg Crit Care 2015; 25(2):256-262.
9. Drobatz KJ, Cole SG. The influence of crystalloid typeon acid-base and electrolyte status of cats with urethralobstruction. J Vet Emerg Crit Care 2008; 18(4):355-361.
10. Cooper ES. Controversies in the management of felineurethral obstruction. J Vet Emerg Crit Care 2015; 25(1):130137.
11. O’Hearn AK, Wright BD. Coccygeal epidural with local
anesthetic for catheterization and pain management in thetreatment of feline urethral obstruction. J Vet Emerg Crit Care
2011; 21(1):50-52.
12. Lees GE, Osborne CA, Stevens JB, Ward GE. Adverse
effects caused by polypropylene and polyvinyl feline urinary
catheters. Am J Vet Res 1980; 41(11):1836-1840.
13. Galluzzi F, De rensis F, Menozzi A, Spattini G. Effect of
intraurethral administration of atracurium besylate in malecats with urethral plugs. J Small Anim Pract 2012; 53:411415.
14. Cooper ES, Owens TJ, Chew DJ, Buffington CA. A protocol
for managing urethral obstruction in male cats without
urethral catheterization. JAVMA 2010; 237(11):1261-1266.
15. Francis BJ, Wells rJ, rao S, Hackett TB. retrospective study
to characterize post-obstructive diuresis in cats with urethralobstruction. J Feline Med Surg 2010; 12:606-608.
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for the treatment of obstructive feline idiopathic cystitis. J
Feline Med Surg 2015; DOI: 10.1177/1098612X15621603.
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reducing cats’ stress. J Feline Med Surg August 2015 [Epubahead of print]; DOI: 10.1177/1098612X15599420.
19. Eisenberg BW, Waldrop JE, Allen SE, et al. Evaluation ofrisk factors associated with recurrent obstruction in catstreated medically for urethral obstruction. JAVMA 2013;
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GREGORY F. GRAUERGregory F. Grauer, DVM, MS, Diplomate ACVIM(Small Animal Internal Medicine), is a professor
and Jarvis Chair of Medicine, Department ofClinical Sciences, at Kansas State University
College of Veterinary Medicine. His clinicaland research interests involve the small animal
urinary system. He is on the board of directorsof the IRIS and American Society of Veterinary
Nephrology and Urology. Dr. Grauer received
his postgraduate training in internal medicine
at Colorado State University. He has been afaculty member at University of Wisconsin
and Colorado State University Colleges ofVeterinary Medicine.

TODAY’S VETErINArY PrACTICE | July/August 2016 | tvpjournal.com

Peer reviewed

FELINE UrETHrAL OBSTrUCTION: DIAGNOSIS & MANAGEMENTCE TEST. FELINE URETHRAL OBSTRUCTION:DIAGNOSIS & MANAGEMENT
This article is RACE-approved for 1 hour of continuing education credit. To receive credit,take the approved test online at VetMedTeam.com/tvp.aspx (CE fee of $5/article).

Learning Objectives
Upon completion of this article, readers should be able to formulate a plan for appropriate diagnostics
that will facilitate patient stabilization prior to relief of a urethral obstruction (UO). Readers should also
have an increased understanding of traditional and nontraditional methods of relieving UO as well assome of the factors that may contribute to recurrent obstruction.

Note
Questions online
may differ fromthose here; answers
are available once
CE test is taken atvetmedteam.com/
tvp.aspx. Tests arevalid for 2 years fromdate of approval.

1. Cats treated for UO have a survival rate todischarge of:a. < 70%
b. 70–80%
c. 80–90%
d. > 90%
2. Classic historical and physical examination
ﬁndings in cats with UO include all of thefollowing except:
a. Stranguria, dysuria, and/or hematuria
b. Anorexia and vomitingc. Perineal and hindlimb edema
d. A large, turgid urinary bladder
3. What is the most signiﬁcant laboratory
abnormality requiring emergent treatment incats with UO?
a. Hyperkalemiab. Hypercalcemia
c. Hyponatremiad. Hypochloremia
4. What type of imaging is recommended for allcats presenting with UO?
a. Abdominal ultrasonographyb. Abdominal radiographyc. Thoracic radiographyd. Abdominal computed tomography
5. What emergent IV therapy is most effectivein rapidly reducing serum potassium levels?
a. Calcium gluconate
b. Sodium bicarbonatec. Dilutional ﬂuid therapy
d. Regular insulin and dextrose46

6. True/False: Therapeutic cystocentesis iscontraindicated in cats with UO.
7. What type of urinary catheter is notrecommended for use as an indwelling
catheter?
a. Polypropylene (Tomcat catheter)b. Polyvinyl (red rubber catheter or infant
feeding tube)
c. Polytetraﬂuroethylene (Slippery Sam Tomcat
Urethral Catheter)d. Polyurethane
8. True/False: Cats with UO must be treatedwith urethral catheterization; othertreatment protocols are ineffective.
9. When are antimicrobials indicated in thetreatment of UO?
a. When cats present for recurrent UO
b. When quantitative bacterial culturesuggests significant bacteriuria
c. To prevent UTI during urethralcatheterizationd. In all cats being discharged after urethralcatheterization
10. The use of _________ has become standard
in cats with UO to help prevent recurrent
UO secondary to urethral irritation andspasms.
a. Meloxicam
b. Diazepamc. Alpha-1 antagonists
d. Calcium gluconate

TODAY’S VETErINArY PrACTICE | July/August 2016 | tvpjournal.com