Urethral Obstruction in Cats - Green Flashcards
What are the 2 most frequent causes of Urethral obstruction do to in cats?
- Urethral plug
- Idiopathic
What are Urethral Calculi?
“Formed concretions”
95% mineral
<5% matrix
What makes up Urethral Plugs?
What is the most common mineral component?
- > 50% matrix (debris)
- Struvite is the most common mineral component
Describe the Clinical Presentation of Urethral Obstruction.
-
Early ⇒ 12-48 hrs.
- No C/S, normal BUN & serum Creatine or mild azotemia
-
Advanced ⇒ 48-72 hrs
- Post-renal azotemia & Oligo or anuria
- Death ⇒ 72-120 hrs. post obstruction
-
Post-obstructive diuresis ⇒ 2-7 d.
- Always measures the urine output for several days after to make sure the kidneys are still healthy
What are some C/S of Early or Partial Urethral obstruction?
What other syndrome can it mimic?
- Stranguria
- Pollakiuria
- Hematuria
- mimics FIC
What are some C/S of Late or Complete Urethral Obstruction?
- Vomiting
- Anorexia
- Lethargy
- Dehydration
Which 2 metabolic abnormalities are major contributing factors
to mortality in blocked cats when they are severe?
- Hyperkalemia
- Metabolic acidosis
(Can cause cardiac arrest)
What 2 metabolic factors contribute the most to the anorexia, lethargy & vomiting
seen in blocked cats?
- Progressive azotemia ⇒ Post-renal or Renal
- Hyperphosphatemia
How does urethral obstruction cause azotemia in cats?
- Increased intratubular pressure
- Decreased GFR
- Decreased renal perfusion
What’s going on during Post-Obstructive Diuresis?
- Self-limiting ⇒ lasts 2 - 7 d.
- Often proportional to the severity of intial azotemia
- Body is trying to excrete the retained solutes & H2O
- A transient renal tubular defect in Na+ reabsorption & insensitivity to ADH occurs ⇒ a form of Diabetes Insipidous!
Why do you generally want to perform a Cystocentesis on a Blocked cat?
- Therapeutic ⇒ prevents bladder rupture & buys you some time
- Diagnostic ⇒ can collect urine sample
- Makes passing the urethral catheter easier
Which 2 drugs do you NEVER give to a FIC or Blocked Cat?
- NSAIDs
- Steroids
How does severe hyperkalemia appear on an ECG?
Is this correlated to serum [K+]?
- Sinoventricular rhythm (atrial standstill) ⇒ Tented T waves, w/ P waves still present
- Not necessarily
What 3 things will dictate your clincal approach to Complete Urethral Obstruction?
- Severity of Uremia
- Patient’s cardiovascular stability
- Magnitude of bladder distention
(NB: DX tests & TX must occur concurrently!)
List the top 2 fluid choices for Blocked Cats?
Caveat?
- LRS & Normosol-R are best
- UNLESS pt is HyperK+ ⇒ than 0.9% NaCl is better
How do you TX Hyperkalemia?
- Antagonize <3 effects ⇒ 10% Ca2+ gluconate
- Promote intra-cellular K ⇒ Dextrose + regular insulin
What are the benefits of a decompressive cystocentesis?
- Life-saving
- Buys time
-
May prevent bladder rupture
- decreases intraluminal pressure
-
Allows renal excretory fxn to resume
- Increased GFR by decreasing intraluminal pressure
- May help dislodge a urethral plug
- Provides better quality urine sample for UA
How do you perform Hydropulsion of a plug w/in the urethra?
- Sterile & gentle technique
- Stay sutures to stabilize the prepuce
- Extend penis caudally
- Inject sterile saline to hydropulse the plug back into the bladder
When should you remove an indwelling urethral catheter?
- Relatively easy catherization
- Clear urine after flushing
- Minimally sick cat
When should you place an indwelling catheter?
- Difficult catheterization
- Very bloody or cloudy urine after flushing
- Very sick cat
Which catheters are good to use for placing an indwelling catheter?
5 French polyvinyl
(fewer problems w/ outflow obstruction)
(pick a soft one.. less irritating to cat)
Why should you avoid using antimicrobials in patients w/ Indwelling Catheters?
UTI still will develop but the organisms will be resistant
How much urine can you expect to be produced during Post-Obstructive Diuresis?
up to 20 mL/Kg/hr.
What drug should you use to TX urethral sapsms?
Acepromazine
(spasmolytic)
