Introduction
A urinary catheter is a thin tube passed up the urethra into the bladder. Technicians place catheters to collect a urine sample, relieve a blocked urethra, measure urine output and keep a down patient clean and dry. A recumbent patient is one that cannot stand or walk on its own, such as a dog after spinal surgery or a patient with severe illness. These two skills belong together: many recumbent patients need a catheter, and every catheter needs daily nursing care.
The VTNE content outline lists "Perform nursing procedures and maintenance of prescribed treatments (including but not limited to catheterization, wound management, and bandaging)" and "Provide a safe, sanitary, and comfortable environment for patient" as Domain 5 tasks, with knowledge area 34, animal nursing procedures and rehabilitation therapies.1
Key facts
- Red rubber catheters suit intermittent (one-time) catheterization; Foley catheters, made of soft silicone with a balloon at the tip, are preferred for indwelling use.2
- Test a Foley balloon before placement, deflate it, then inflate it with sterile saline or water once the tip is in the bladder.2
- In the female dog the urethral papilla sits on the ventral floor of the vestibule, about 2 to 4 cm inside the vulva depending on size.3
- Normal urine output is 1 to 2 mL/kg/h.5 Alert the veterinarian if output falls to 0 to 0.5 mL/kg/h.2
- Keep the collection bag below the patient at all times so urine cannot flow back into the bladder.2
- Prophylactic antibiotics are not recommended for catheterized patients because they raise the risk of antibiotic resistance.2
- Turn a laterally recumbent patient every 2 to 4 hours and record which side is down.6
- Never give food or water to a patient lying in lateral recumbency; sit it up in sternal recumbency first.6
How the VTNE tests this
- Choose the catheter: match red rubber, Foley or tomcat catheters to the patient and the job (Domain 5 Task C; K34).1
- Find the landmark: locate the urethral papilla in the female dog, or know where resistance is felt in the male dog.
- Calculate urine output: convert a measured volume over a set time into mL/kg/h and decide whether it is acceptable.
- Prevent complications: pick the nursing step that best prevents catheter-associated infection, decubital ulcers or urine scald (Domain 5 Task E).1
Core concepts
Why catheterize
Indications include measuring urine output, relieving a urethral obstruction, keeping a nonambulatory patient clean and giving medications straight into the bladder.2 Catheters are also used for urinalysis samples, checking that the urethra is open, contrast radiography and long-term urine collection.3 Recognized complications are urethral irritation, bleeding, infection, rupture of the bladder or urethra, and incontinence with chronic use.3
The safest catheter is the one that is never placed. The best way to prevent a catheter-associated urinary tract infection (CAUTI) is to avoid catheterization that is not needed.2
Catheter types
Catheter size is given in French (Fr) units. In the size table below, each French unit works out to about one third of a millimeter of outer diameter, so an 8 Fr catheter is about 2.7 mm across.2
| Catheter | Typical patient | Technician notes |
|---|---|---|
| Red rubber (latex) | Dogs, intermittent catheterization | Flexible; good for one-time collection or emptying; commonly leaks if left in. Secure with a tape butterfly sutured near the vulva or prepuce.2 |
| Foley (silicone, balloon tip) | Dogs needing an indwelling catheter, often females | Softer and less irritating; the inflated balloon rests on the bladder neck, which limits leaks and keeps the catheter from slipping out.2 |
| Tomcat (open-ended, 3.5 Fr) | Male cats with urethral obstruction | Used to flush and dislodge the blockage; then removed and replaced with a soft indwelling 3.5 or 5 Fr catheter that is sutured in place.4 |
| Soft indwelling feline catheter | Cats after deobstruction | 3.5 to 5 Fr; attach to a closed collection system for output monitoring.34 |
Sources: Champion and Cheek, Today's Veterinary Nurse 2024; University of Guelph VETM 4540; Today's Veterinary Nurse, urethral obstruction in male cats.
| Body weight | French size | Outer diameter |
|---|---|---|
| Under 15 lb | 4 to 5 Fr | 1.3 to 1.7 mm |
| 15 to 39 lb | 6 to 8 Fr | 2 to 2.7 mm |
| 40 to 80 lb | 10 to 12 Fr | 3.3 to 4 mm |
| Over 80 lb | 14 to 16 Fr | 4.7 to 5.3 mm |
Source: Champion and Cheek, Today's Veterinary Nurse 2024, Table 1. A guideline only: body condition, clinical signs and experience also guide the choice.2
Female dog anatomy
The vulva opens into the vestibule. The urethral opening (papilla) lies on the ventral midline of the vestibular floor, just caudal to the narrowing where the vestibule meets the vagina. The pubis can be felt through the vestibular floor cranial to the opening. The papilla feels like a small bump or depression about 2 to 4 cm in, roughly the first to second joint of your finger.3 The larger vaginal opening lies dorsal to it, so a catheter that slides up and away has usually gone into the vagina.2
Procedure or technique
Female dog, digital method
- Gather an appropriately sized catheter, sterile water-based lubricant, sterile gloves, an antiseptic such as dilute chlorhexidine or iodine for flushing the vulva, and a closed collection system.2
- For a Foley catheter, inflate the balloon to check for leaks, then deflate it.2
- The patient is usually sedated to the point of muscle relaxation and placed in sternal or lateral recumbency. An assistant holds the tail, clips long hair and cleans the area around the vulva.2 Clip long hair only; clipping down to the skin causes irritation.3
- Premeasure the catheter length to reach the bladder.3
- With a sterile gloved, lubricated finger, enter the vulva, find the papilla on the ventral floor and rest your fingertip lightly on it. Pressing hard closes the opening.3
- Slide the lubricated catheter under your fingertip into the urethra. Resistance, or a catheter that retreats, suggests it has entered the vagina.2
- Urine flowing confirms bladder entry; a small bladder may need gentle syringe suction. Placement should be confirmed with radiography, then the stylet is removed and the Foley balloon inflated.2
- Attach the closed collection system right away.2
When the papilla cannot be felt, an otoscope, vaginal speculum or laryngoscope can help you see it. Very small dogs are often treated like cats: a blind technique with the catheter kept on the ventral aspect of the vagina.2
Male dog
The male dog is placed in lateral or dorsal recumbency. Retract the prepuce caudally with one hand while the other pushes the penis forward, wash the penis, and advance the premeasured, lubricated catheter. Slight resistance is normal just past the os penis and again at the prostate.3
Male cat
Pull the penis straight back in a caudal direction so the penile urethra runs parallel to the spine; this reduces the curve in the urethra. If resistance is met during deobstruction, small amounts of saline are flushed while the catheter is advanced.3 Deobstruction is done under anesthesia with aseptic technique.4
Daily care of an indwelling catheter
- Wear gloves whenever you handle the catheter or bag.2
- Clean the perineum at least every 24 hours with gentle soap and water, more often if soiled. Wipe the external tubing with 0.5% to 2% chlorhexidine on sterile gauze, up to 3 times a day.2
- Place the bag in a clean container below the patient. Check for disconnection, leaks and kinks; replace a compromised system.2
- If an IV fluid bag is used as the collector, clamp the line before moving the patient so urine cannot run back, and have a protocol to unclamp it afterward.2
- Record urine output every 4 hours and compare "ins" (fluids given) with "outs" (urine produced).26
- Watch for fever, lethargy, inappetence, vomiting, irritation at the vulva, pyuria (pus in urine), and red or brown urine. Report these; urinalysis and culture confirm infection.2
Flowchart: four-hour catheter check
Care of the recumbent patient
Prolonged recumbency affects almost every body system. The technician's treatment sheet should spell out each task so nothing is missed.6
| Problem | What the technician does |
|---|---|
| Decubital ulcers (pressure sores) | Thick, dry, clean bedding; thicker padding for heavier patients. Turn every 2 to 4 hours and record the side down. Inspect skin over bony prominences. Sternal recumbency is ideal, with the hind legs flipped every few hours.6 |
| Urine scald and soiling | Check bedding on a schedule and change it whenever soiled. Wash soiled skin with mild soap and water, then dry thoroughly; soap and water work better than dry shampoo.6 |
| Bladder that will not empty | Manual expression 4 to 6 times daily, or an indwelling catheter placed and managed aseptically.6 |
| Aspiration | Feed and give water only in sternal recumbency, never lateral.6 |
| Hypothermia and burns | Except forced-air units, never place a warming device directly on the skin; use a towel layer and check temperature often.6 |
| Muscle atrophy and stiff joints | Massage, passive range of motion (PROM: the technician moves each joint through its comfortable range), assisted standing and sling walks without letting the feet drag.6 |
| Atelectasis of the down lung | Regular turning; sternal positioning improves oxygenation. Coupage may help clear airway secretions.6 |
Source: Veterinary Practice News, 10 tips to manage recumbent veterinary patients.
Atelectasis means collapse of part of the lung. Coupage is gentle cupped-hand percussion of the chest wall. PROM and walking also improve circulation and lymph drainage, which limits limb edema.6
Species differences
- Male dog: lateral or dorsal recumbency; expect slight resistance at the os penis and prostate.3
- Female dog: harder; usually sedated; digital method in larger dogs, visualization aids or a blind technique in small dogs.23
- Male cat: most often catheterized for urethral obstruction, under anesthesia; 3.5 Fr tomcat catheter to unblock, then a soft 3.5 to 5 Fr indwelling catheter sutured in place.34
- Very small dog: often treated like a cat, with a blind technique and the catheter advanced along the ventral aspect of the vagina.2
Calculation
Worked example. A 25 kg dog with a closed collection system produces 150 mL of urine in 4 hours. Is output normal?
Urine output = volume / (body weight x time)
= 150 mL / (25 kg x 4 h) = 150 mL / 100 kg·h = 1.5 mL/kg/h
The kg and h units stay in the denominator, giving mL/kg/h. 1.5 mL/kg/h is inside the normal range of 1 to 2 mL/kg/h.5 If the same dog made only 40 mL in 4 hours (0.4 mL/kg/h), that falls in the 0 to 0.5 mL/kg/h oliguria to anuria range and the veterinarian must be told.2
Safety, legal and client education
- Take extra care in patients with a bleeding disorder (coagulopathy), because urethral microtears can bleed. Use adequate lubrication and the right size.2
- Patients with diarrhea have a higher risk of fecal contamination of the catheter and need more frequent cleaning.2
- Do not leave a catheter in longer than needed; one infection-reduction strategy is not exceeding 72 consecutive hours.2
- Explain to owners of a down pet going home that turning, padding, keeping the skin clean and dry, and bladder care continue at home. Ask the veterinarian to demonstrate bladder expression if it is prescribed.
Common mistakes and exam traps
- Hanging the collection bag on the cage door above the patient. It must always be lower than the bladder.2
- Giving antibiotics "to prevent" CAUTI. Prophylactic antibiotics are not recommended.2
- Pressing hard on the female dog's papilla; this closes the opening.3
- Choosing a red rubber catheter for a long indwelling stay; Foley catheters are preferred because red rubber catheters leak.2
- Feeding a patient in lateral recumbency. Always sit it sternal first.6
- Calculating output with the wrong weight unit. Use kilograms, not pounds.
Quick review
- Red rubber: intermittent use. Foley: indwelling, balloon on the bladder neck.
- Tomcat 3.5 Fr: unblocking male cats, then a soft indwelling catheter.
- Female dog papilla: ventral vestibular floor, 2 to 4 cm in, caudal to the pubis.
- Male dog: resistance at the os penis and prostate is normal.
- Male cat: pull the penis caudally, parallel to the spine.
- Normal urine output: 1 to 2 mL/kg/h. 0 to 0.5 mL/kg/h: alert the veterinarian.
- Bag below the patient, closed system, gloves for every handling.
- Clean the perineum at least every 24 hours; record output every 4 hours.
- No prophylactic antibiotics; remove catheters as soon as they are not needed.
- Turn every 2 to 4 hours and record the side down.
- Thick dry padding; wash and dry soiled skin to prevent urine scald.
- Feed only in sternal recumbency; PROM to prevent stiffness and atrophy.