Manejo del Gato con Obstrucción de Vías Urinarias
Urinary tract obstruction is a very common problem among cats, because they can easily suffer from lower urinary tract illnesses.
Usually, if the obstruction is detected on time by the owners and properly cared for in the clinic, the possibility of successfully keeping it under control is high.
Cats with urinary tract obstruction must be evaluated thoroughly to identify whether they already show secondary systemic manifestations to a prolonged time being unable to urinate.
It is recommended to perform initial blood tests including urea, creatinine, glucose, electrolytes, and hematocrit or hemogram if possible. The heart must be monitored since hyperkalemia is the most commonly shown electrolyte imbalance. There can be variations in the ECG such as bradycardia, absence of the P wave, and abnormal QRS complexes.
Before starting the unobstruction procedure, it is important to begin fluid therapy with isotonic crystalloid solutions, such as Hartmann's solution. The recommended initial dose ranges from 10 to 20 mg/kg, and the patient is reevaluated every 10 to 15 min to check if an adjustment is necessary. If the patient is hyperkalemic, 10% calcium gluconate can be added (0.5–1 ml/kg for 10 min).
Once the patient is stable, one can initiate the procedure to free the urethral obstruction. In extreme cases, a guided cystocentesis can be performed in order to empty the bladder as the patient stabilizes; however, this carries the risk of bladder laceration and leakage into the abdominal cavity. In the case of idiopathic cystitis, the severe manipulation can even puncture the bladder.
It is always recommended to perform an abdominal radiographic study to rule out the presence of radiopaque calculi, which are often present.
An ultrasonographic study of the bladder is also highly useful to assess it and the characteristics of its contents.
Once stabilized, the patient must be sedated or anesthetized so it can be more easily handled; this will also avoid pain and make the urinary tracts relaxed.
The cat is placed in dorsal recumbency with the pelvic limbs pulled forward to expose the penis. The penis is softly held and a massage is performed to try and eliminate the plug or calculus that could be in the distal part of the urethra. An intravenous catheter, connected to an extension, which is in turn connected to a syringe with saline solution, can then be introduced. When the catheter reaches the obstructed zone, the penis is pressed between the fingers to obstruct the urethra; the solution is introduced, and the catheter is softly pushed to remove the plug or calculus. Once the whole catheter is inside, it can be replaced by a Tom Cat to cover all of the urethra's length and reach the bladder. Then, the bladder must be emptied and washed with saline solution until the urine comes out clear. While the washings are being done, the bladder can be felt and softly pressed to try and get rid of the sediment. Lastly, the rigid probe is replaced by a flexible one and is attached to the prepuce. It is connected to a urine recollection system, to avoid ascending infections.
The catheter is left behind until the urine comes out clear, usually for 2 to 3 days. The probe is taken out and the patient is observed during the next 24 to 48 hours to check if it can urinate properly before sending it home.
It is important to avoid corticosteroid administration, since they can favor the appearance of urinary tract infections. If infection is suspected, part of the probe can be sent to a laboratory so that a culture and an antibiogram are performed.
If the problem persists, or if there is severe damage in the urethra due to either the obstruction or excessive manipulation that irreversibly damages the urethra, the patient must be referred in order to have a perineal urethrostomy performed.