HOW TO REMOVE URETHRAL OBSTRUCTION IN CATS Urology The release of UO it is performed with washes. The use of an olive-tip catheter (Minnesota catheter) is recommended. This catheter is metallic and has in its tip an olive with a frontal opening; these are available in 21 G caliber with lengths of 1/2, 1, and 1 1/2”; its special shape facilitates its introduction into the urethral lumen without causing injury and gives a greater pressure when performing washing or irrigation of the urethra with sterile saline solution when used with a venoclysis extension and a 3- or 5 ml syringe (Figure 7). Figure 7. Olive-tip catheters (Minnesota catheters) of different lengths. increases in UO due to a greater trauma and inflammation of the urethral mucosa. Catheter length is variable (11, 14 or 18 cm) depending on the size of the patient; the tip should reach the urinary bladder trigone (Figure 9). Figure 9. Urinary catheter in a male cat. Top: The X-ray image showing the position of a urethral catheter. Down: Endoscopic image of the urinary bladder trigone, the urinary catheter emerging from the urethral lumen. Note how with magnification it is possible to observe the longitudinal grooves in the catheter walls; this characteristic of the Teflon catheter allows its insertion into the urethral lumen without trauma to the urethral mucosa. Once the release of the UO has been performed, the use of flexible urinary catheters of polytetrafluoroethylene (Teflon) or low-density polyethylene with barium (radiopaque) or without barium (radiolucid), with or without stylet, is recommended to facilitate the continued emptying of the bladder. The use of conventional semi-rigid polypropylene catheters should be avoided, as these tend to be more traumatic and irritant to the urethral mucosa (Figure 8). In an average-size cat, it is suggested to use 3.5 Fr catheters; those of larger diameter, for example 5 Fr, are associated with Figure 8. Different feline urinary catheters. A: Flexible polytetrafluoroethylene (Teflon); B: Flexible polyethylene with barium and stylet; C: Flexible polyethylene without stylet D: Semirigid polypropylene. Maneuvers to release the UO and urethral catheter placement The olive-tip catheter should be selected based on the diameter of the urethra and the size of the patient’s penis. It should then be connected to a venoclysis extension and a 3- or 5 mL syringe containing saline solution and water-soluble lubricant placed on the tip of the catheter. Because the penile urethra is at an angle of approximately 45° in relation to the pelvic urethra, to insert the catheter the penis must be pulled in a caudodorsal direction to align the urethra parallel to the vertebral column (6) (Figure 10). Introduce the catheter gently into the urethra opening, turning it on it is axis and irrigating (washing) with saline solution while at the same time moving it forward with slight pressure on the penis around the catheter so the pressure of the fluid moves the element that is blocking the urethra (16) (Video 3). Avoid pushing the catheter sharply, as this may severely injure the urethral mucosa. Obstructions should be released only by irrigation of the urethra. Once REMEVET 5
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