Author: Erik Zager, DVM, DACVECC
Philadelphia Animal Speciality and Emergency
Feline Lower Urinary Tract Disease (FLUTD) is the catch-all term for any lower urinary signs in cats, including urethral obstructions, UTI, behavioral periuria (urinating outside the litterbox), etc. Feline idiopathic cystitis (FIC) is a type of FLUTD where there is bladder inflammation without an identifiable cause. It is multifactorial with evidence pointing to risk factors including: stressful environments, obesity, indoor only lifestyle, multi-cat households, recent moves, long-haired cats, pure-breed cats, and presence of inter-cat aggression.
Urethral obstructions can occur due to FIC as there is an accumulation of mucus and cellular debris secondary, or obstruction can occur from UTIs, cystolithis, or neoplasia. FIC resulting in urethral plugs are the majority of cases of male feline urethral obstruction. UTIs are possible with incidences from 1-10% depending on study. Cystolithiasis is a less common cause of urethral obstruction.
Cats with urethral obstruction typically present with large and FIRM bladders and painful abdomens. Cats can also present in shock with bradycardia, weakness, and hypothermia. The minimal database should include an ECG, point of care blood work that at least includes BUN, Creatinine, and potassium. Minimum recommended diagnostics. Other diagnostics such as blood pressure, PCV/TS, urinalysis +/- culture (once urine is obtained from catheter) should also be considered. Abnormalities on the ECG that could indicate hyperkalemia include: bradycardia, loss of P-wave, tall T-wave, QRS widening, atrial standstill, and ventricular fibrillation.
Treatment of feline urethral obstruction is aimed at relieving the obstruction and treating the secondary complications such as hyperkalemia, shock, and pain. Hyperkalemia treatment is often the most pressing issue for patients with severely elevated potassium. Multiple treatments should be instituted for hyperkalemic patients. IV fluid therapy with any balanced crystalloid (LRS, Plasmalyte, Saline, etc) will treat shock as well as reduce serum potassium levels. Intravenous calcium will stabilize cellular membranes and reduce arrhythmias. 50mg/kg of calcium gluconate (0.5ml/kg of 10% calcium gluconate) is the calcium treatment of choice as it is safer than calcium chloride. It should be given slowly (about 5 minutes) with ECG monitoring. Dextrose with short acting insulin (Humulin-R, Novalin-R; 0.2U/kg) will help drive potassium intracellularly. Dextrose can be given alone to induce endogenous insulin release. If short acting insulin is administered ensure you administer bolus of dextrose and dextrose CRI for at least 4 hours to prevent hypoglycemia. Do not give long acting insulin.
Once initial stabilization has been performed, the patient should be unblocked as soon as possible. Care should be taken when sedating cats with severe electrolyte abnormalities or evidence of shock. If possible, take every step to perform stabilization FIRST before sedation for unblocking. In cats with evidence of shock, avoid dexmedetomidine due to the severe decrease in cardiac output that can occur. Coccygeal blocks can be helpful for pain control and ease of unblocking and guide videos are available from vetgirl’s youtube channel. Sterile preservative free lidocaine must be used.
Cats have a flexure that can make urethral catheter placement difficult. Use gentle but FIRM traction on the prepuce and pull caudally to straighten out the urethra and aid in catheter placement. Sometimes pulling upwards (ventrally) can help as well. Keep gentle pressure on the catheter to keep the tip of the catheter placed in the urethra. Once the prepuce is being pulled, continue advancing the catheter. Having a second person using sterile saline as a flush to clear debris is also very helpful to advance the urethral catheter.
If catheterization is not possible, then a decompressive cystocentesis can be considered. It should still be done with sedation to prevent bladder trauma and rupture, and an extension set should be used so a second person can aspirate the urine while the person performing the cystocentesis holds still.
Once the catheter has been placed, you can consider additional diagnostics such as radiographs to check for stones and ensure catheter placement, urinalysis and urine culture.
Post-catheterization, the cats should be kept on IV fluids. The rates may need to be high in cases of post-obstructive diuresis. Monitor potassium levels, as many cats will develop a hypokalemia after unblocking and need supplementation. Pain control can typically be accomplished with buprenorphine. Do NOT use NSAIDS due to the risk of acute kidney injury. Antispasmodics such as prazosin have not had any strong supporting evidence for their use. The urinary catheter with a closed collection system is typically kept in place for at least 24-36 hours to allow decreased urethral inflammation. Unfortunately, even with ideal management, approximately one third of cats will have recurrent events.
