Urethral Catheterization in Male Ferrets

Introduction

Urethral obstruction is usually associated with adrenocortical disease in pet ferrets. Adrenal disease may cause a rise in androgen levels, which in turn can cause the prostate to enlarge. Prostatomegaly can compress the urethra causing an obstruction of urine outflow.

Urethral catheterization of the male ferret is challenging due to the animal’s small size and J-shaped os penis, however the principles of catheterization as well as monitoring during catheter placement are essentially the same as in the domestic cat.

Urethral catheterization video

Video produced by Dr. M. Scott Echols and narrated by Dr. Natalie Antinoff.

Equipment needed

• A 24-gauge venous indwelling catheter with the needle removed
• Urinary catheter (see step 1 below)
• Sterile water-soluble lubricant
• Sterile gloves
• Dilute chlorhexidine solution
• Sterile saline
• Sterile gauze sponges
• Small sterile drapes or towels
• Syringes
• Suture
• White tape
• Needle holders
• Bandage material
• +/-  Elizabethan collar.

Potential complications

Urethral tear or rupture secondary to rough or repeated attempts at catheterization.

Step-by-step instructions

• Select a urinary catheter designed for use in the ferret such as the 3.0-Fr open-ended silicone catheter called a “Slippery Sam” or the steam autoclavable 3.0-Fr tomcat urethral catheter. Alternatively, a 20-or 22-gauge 8-inch jugular catheter may serve as a makeshift urinary catheter, and a 3.5-Fr red rubber catheter may be placed in a  very large male.
• Place the ferret under general anesthesia to achieve adequate muscle relaxation. Avoid ketamine since the kidneys excrete it.
• Provide supplemental heat and pre-emptive analgesia such as buprenorphine (0.01-0.3 mg/kg q8-12h SC, IM, IV), butorphanol (0.1-0.5 mg/kg q4-6h SC, IM or 0.025-0.1 mg/kg/hr IV), or fentanyl (2.5-5.0 µg/kg/hr).
• Place the patient in dorsal recumbency.
• Extrude the penis with digital pressure applied to the prepuce craniodorsally.
  

  Figure 1. Extrusion of ferret penis.Click image to enlarge.

  Once the J-shaped os penis is exposed, grasping the prepuce at the mucocutaneous junction with a gauze sponge (not shown here) can minimize the risk of the penis slipping back into the prepuce.

• Allow an assistant to gently clean and flush the penis with dilute chlorhexidine solution and saline.
• Use the 24-gauge catheter to identify the small, slit-like urethral opening located on the ventral surface of the penis just above to the J-shaped curve. Gently insert the catheter between the two osseous projections of the penis.
  

  Figure 2. Use of a 24-ga catheter with the needle removed to find the urethral opening. Click image to enlarge.

  

  Figure 3. Dilating the urethra with a 24-gauge catheter with the needle removed. Click image to enlarge.

• Once the urethral opening has been dilated with the 24-gauge catheter it is usually easier to insert and thread the urethral catheter that will be left in place.
  

  Figure 4. Once the urethral opening has been dilated, it is usually easier to insert the urethral catheter. Click image to enlarge.

• If resistance is met, flush sterile saline as the urinary catheter is advanced. If resistance persists, proceed with caution as urethral tear or rupture can occur.
• Once the catheter is in place, flush the bladder with sterile saline. Significant amounts of blood and sometimes pyuria may be present.
• Place tape tabs on the catheter at the level of the prepuce then suture the catheter in place.
  

  Figure 5. Suturing the catheter in place. Click image to enlarge.

• Attach sterile IV tubing and a small, sterile fluid bag to create a closed collection system.
• Some clinicians routinely fit the ferret with an Elizabethan collar and place a body wrap to the ferret’s torso to secure the line to the ferret. Secure the collar by criss-crossing gauze under the forelimbs in a figure eight pattern or by placing a piece of foam pipe insulation between the collar and the shoulders to prevent slipping.

Maintain the urinary catheter for no more than 1 to 3 days. See Urethral obstruction in the ferret for tips on monitoring and follow-up care.

If attempts at urethral catheterization are unsuccessful, the goal must be to sufficiently stabilize the patient so that it can undergo exploratory laparotomy and emergency cystotomy. Perform cystocentesis using a butterfly catheter and three-way stopcock for rapid bladder drainage. Only perform cystocentesis once since the risk of urine leakage and uroabdomen rises every time the friable bladder wall is aspirated. Whenever possible, refer a ferret requiring emergency surgery to a small mammal veterinarian since additional procedures such as adrenalectomy may also be indicated during exploratory surgery.

References