Feline lower urinary tract obstruction emergency protocol...

Alright, let's get this cat stabilized. A 4-year-old MN DSH blocked for 24 hours, K+ 8.5, bradycardic at 100 bpm – this is a critical, life-threatening emergency. The hyperkalemia is driving that bradycardia, and it will kill this patient if not addressed immediately. We don't have hours; we have minutes.

Here's the step-by-step protocol:

Step 1: Immediate Stabilization – Address the Hyperkalemia (The Killer)

ECG First, Always: Get an ECG on this cat right now. We need to see the specific changes (tall T waves, widened QRS, absent P waves) and monitor response to treatment.

IV Access: Place at least one large-bore IV catheter (22g cephalic or saphenous). If you can get two, even better, but don't delay treatment for a second one.

Cardioprotection:

Administer Calcium Gluconate 10% at 0.5-1.5 mL/kg IV slow over 10-15 minutes. This is critical. It stabilizes the cardiac cell membranes, counteracting the effects of hyperkalemia on the heart, but it does not* lower serum potassium. Monitor the ECG continuously during administration; if the bradycardia worsens or you see further changes, slow or stop the infusion.

Shift Potassium Intracellularly:

* Regular Insulin: Administer 0.25-0.5 U/kg IV.
* Dextrose: Immediately follow with a dextrose bolus or CRI to prevent hypoglycemia. Provide 1-2 grams of dextrose per unit of insulin given. A common approach is a 2.5% or 5% dextrose CRI, or a bolus of 0.5-1 g/kg dextrose IV, followed by a CRI.
Note:* Bicarbonate (sodium bicarbonate 1-2 mEq/kg IV over 15-20 minutes) can also shift potassium, especially if the cat is severely acidotic, but insulin/dextrose is generally faster and more reliable for severe hyperkalemia.

Fluid Therapy: Start an IV fluid infusion with 0.9% Sodium Chloride (NaCl). This is crucial because it's potassium-free and will help dilute serum potassium and promote renal excretion once the obstruction is relieved. Avoid LRS or Plasmalyte initially, as they contain potassium. Start with a conservative rate, perhaps 5-10 mL/kg/hr, and be prepared to bolus if cardiovascular parameters are poor, but remember cats are sensitive to fluid overload.

Pain Management: Once initial cardioprotection is underway and the cat is slightly more stable, administer an opioid. Butorphanol 0.2 mg/kg IV is a good choice for sedation and mild analgesia, which will help with handling and the unblocking procedure. A full mu agonist like methadone (0.1-0.2 mg/kg IV) can also be used if the cat is stable enough.

Step 2: Unblocking Technique

Once the cat is cardiostable and the ECG shows improvement (e.g., heart rate increasing, T waves normalizing), we proceed with unblocking.

Sedation: This is non-negotiable. Do not attempt to unblock an awake, stressed cat.

* My preference for a hyperkalemic cat is often Butorphanol 0.2 mg/kg IV first, then a dissociative/hypnotic.
* Alfaxalone 1-2 mg/kg IV titrated to effect is excellent due to its rapid onset and recovery, and minimal cardiovascular depression.
* Alternatively, Ketamine 2-5 mg/kg IV + Midazolam 0.2 mg/kg IV can be used.

Positioning & Prep: Dorsal recumbency, tail taped out of the way, prep the perineal area with antiseptic solution (avoiding the urethral opening initially). Extrude the penis gently.

Hydropropulsion: This is the safest method.

* Use a sterile, well-lubricated open-ended tomcat catheter (3.5 Fr or 4 Fr).
* Advance the catheter to the tip of the penis.
* With gentle pressure, occlude the urethral opening around the catheter.
* Flush sterile saline or LRS (a small amount, 1-2 mL) forcefully through the catheter while simultaneously applying gentle, continuous pressure on the bladder. This hydraulic force helps dilate the urethra and push the plug back into the bladder.
Do NOT* use excessive force with the catheter itself; you want to hydropropulse the plug, not ram the catheter through it.

Catheter Placement: Once hydropropulsion is successful, advance the tomcat catheter into the bladder.

Secure Catheter: Once in the bladder, secure a closed collection system (urinary catheter + extension set + collection bag). This prevents ascending infection and allows for accurate urine output monitoring. Suture the catheter to the prepuce or surrounding skin.

Step 3: Post-Obstruction Management

The crisis isn't over once the cat is unblocked. Post-obstructive diuresis and electrolyte imbalances are common.

Fluid Management: Continue IV fluids. 0.9% NaCl is preferred initially until electrolytes normalize. Monitor urine output (UOP) closely. Post-obstructive diuresis is a real phenomenon; the kidneys, after being under pressure, may "flush" excess water and electrolytes. You may need to replace fluid losses aggressively if UOP is high (e.g., 2-4 mL/kg/hr).

Electrolyte Monitoring: Recheck electrolytes (K+, Na+, P) every 2-4 hours initially, then every 6-8 hours for the first 24 hours. Hypokalemia and hypophosphatemia are common after unblocking due to diuresis and shifts. Supplement as needed.

Analgesia & Antispasmodics:

* Continue opioid analgesia (e.g., Methadone 0.1-0.2 mg/kg IV q4-6h or a fentanyl CRI). The urethra will be inflamed and painful.
* Consider an alpha-1 adrenergic antagonist like prazosin (0.25-0.5 mg PO q12-24h) to relax the urethral sphincter.

Urinary Catheter Care: Keep the catheter in for 24-48 hours. This allows the urethra to rest and reduces spasm. Ensure patency; flush gently if needed. Remove the catheter once the urine is clear and the cat is stable.

Antibiotics: Empiric antibiotics are often started due to the risk of ascending infection, although this is debated. If used, a broad-spectrum antibiotic such as Ampicillin/Sulbactam 30 mg/kg IV q8h is a reasonable choice. Discontinue if culture is negative.

Discharge Planning: Once the catheter is removed and the cat is urinating normally, provide diet recommendations (canned food, prescription urinary diet if indicated), stress reduction strategies, and monitor for recurrence.

Step 4: When to Recommend Perineal Urethrostomy (PU)

A PU is a salvage procedure, not a first-line treatment. I defer to surgery for the actual procedure, but the indications for my recommendation are clear:

Recurrent Obstructions: The most common indication. If a cat re-blocks multiple times (e.g., >2-3 times) despite appropriate medical management, dietary changes, and environmental enrichment, a PU is warranted.

Inability to Unblock: If the obstruction cannot be relieved via hydropropulsion or catheterization, or if there's a stricture that prevents catheter passage.

Urethral Trauma/Stricture: If the urethra is severely damaged during attempted unblocking, or if a stricture develops post-obstruction, a PU may be necessary.

This cat is in a critical state. Focus on the hyperkalemia first, get them unblocked, and then manage the post-obstructive phase meticulously. Time is of the essence.